# Why Does The Model 3 Not Use Regen When Using the Brakes.



## fsKotte

I just learned that my M3 (as I believe all Teslas) does not use any regen when I apply the brake pedal. 

This surprised me, as I've had previous EV's that do use some regen when you hit the brake pedal, and I found it to be pretty efficient in utilizing the battery (coast and use no/less energy when you could, and then always use regen when you needed to scrub some speed, via "brake" pedal). 

Anybody know why Tesla has chosen to not use any additional regen when you hit the brake pedal? This is interesting to me because I always thought the most efficient way to drive an EV would be to have the ability to coast when you can, and then regain some energy via regen when you need to slow down. I get that "One Pedal" driving can be fun, but I don't get how it's more efficient, when the regen is always on, and so you're never coasting, always applying energy/electricity to keep the car moving . . . . 

I'm sure I'm missing something here, so appreciate any enlightenment. . . .


----------



## garsh

It's simpler. The brake pedal just operates the hydraulic brakes.


----------



## fsKotte

garsh said:


> It's simpler. The brake pedal just operates the hydraulic brakes.


Sure, and simplicity is nice. The plethora of other EV's that have blended/regen braking upon depressing the brake pedal makes one wonder why Tesla chose not to. It's actually common, among EV's. So is it really just because it's simpler?


----------



## Maevra

fsKotte said:


> I just learned that my M3 (as I believe all Teslas) does not use any regen when I apply the brake pedal.
> 
> This surprised me, as I've had previous EV's that do use some regen when you hit the brake pedal, and I found it to be pretty efficient in utilizing the battery (coast and use no/less energy when you could, and then always use regen when you needed to scrub some speed, via "brake" pedal).
> 
> Anybody know why Tesla has chosen to not use any additional regen when you hit the brake pedal? This is interesting to me because I always thought the most efficient way to drive an EV would be to have the ability to coast when you can, and then regain some energy via regen when you need to slow down. I get that "One Pedal" driving can be fun, but I don't get how it's more efficient, when the regen is always on, and so you're never coasting, always applying energy/electricity to keep the car moving . . . .
> 
> I'm sure I'm missing something here, so appreciate any enlightenment. . . .


Technically if you let your foot off the accelerator even a bit the car is already entering regen mode, so it is already capturing that energy. 
I don't think Tesla needs to add extra regen to the brake pedal as just lifting off the accelerator fully will slow the vehicle down by a LOT.

If you manage the pedal in the right conditions, the car does _sort of _"coast" aka the energy bar is neither black nor green, which I take to mean the car is not using any energy, but also not gaining back energy


----------



## He Chen

You can just release the accelerator pedal and you get regen. You use the brake pedal to use the brakes. And the accelerator pedal to accelerate. And regen when neither is being used.


----------



## Frank99

I agree with Maevra.
In order to press the brake you need to (well, should) take your foot off the accelerator. Assuming that you have Regen set to "Standard", the car will now be slowing as much as it can with regen. There isn't any more regen that it can apply when you start pressing on the brake.


----------



## garsh

fsKotte said:


> Sure, and simplicity is nice. The plethora of other EV's that have blended/regen braking upon depressing the brake pedal makes one wonder why Tesla chose not to.


I drive a blended-brake Leaf every day.
I can't say that I find a blended brake to be "better" in any appreciable way.

It's more complicated. I'd rather just have stronger off-accelerator regen.


----------



## fsKotte

"
I drive a blended-brake Leaf every day.
I can't say that I find a blended brake to be "better" in any appreciable way.

It's more complicated. I'd rather just have stronger off-accelerator regen."
--------------------------------

I had a Fiat 500e for three years, and then a Leaf for about four months (long story there) up until I got the 3. So I too have mostly experienced regen using the brake pedal. 

What I liked about it was that I got to choose when I coasted and when the regen happened. If I took my foot off the accelerator pedal, I mostly coasted, which is a great way to conserve energy sometimes, especially at highway speeds or similar situations. Then, when I needed to slow down, I hit the brake pedal, and then - and only then - did regen happen. Also I controlled the amount of regen because the harder I pressed on the brake pedal, the more regen occurred.

I'm not sure you really ever coast when regen is on "standard" in a M3 . . . . .


----------



## garsh

fsKotte said:


> What I liked about it was that I got to choose when I coasted and when the regen happened. If I took my foot off the accelerator pedal, I mostly coasted


fsKotte, you are *really* misinterpeting what your Leaf is doing.

When you take your foot off the accelerator, you are regenning (unless your battery is as bad as mine, then you might be coasting). If you want to coast, you leave your foot on the accelerator part way so that there is only one central white bubble on the power graph.










> Then, when I needed to slow down, I hit the brake pedal, and then - and only then - did regen happen. Also I controlled the amount of regen because the harder I pressed on the brake pedal, the more regen occurred.


Sure. But the problem is, when you hit the brake pedal, you're not only getting regen, but you're also getting frictional braking at the same time. So you're wasting a portion of that energy as heat in the brake pads. And when you press the brake pedal more, you do get a little more regen, but you get a LOT more frictional braking. It's inefficient.

With a Tesla, when you want more braking, you just let off of the accelerator more. Tesla provides a LOT more regen than Nissan does. And if that's not enough to slow you down, then (and only then) do you hit the brakes and waste energy as heat in the brake pads.


----------



## fsKotte

Maevra said:


> Technically if you let your foot off the accelerator even a bit the car is already entering regen mode, so it is already capturing that energy. (Right, I know. That's not really my issue here.)
> I don't think Tesla needs to add extra regen to the brake pedal as just lifting off the accelerator fully will slow the vehicle down by a LOT. (Right. I get that too. Again, that's not really my issue here, that I'm asking about)
> 
> If you manage the pedal in the right conditions, the car does _sort of _"coast" aka the energy bar is neither black nor green, which I take to mean the car is not using any energy, but also not gaining back energy


Okay, now that last sentence, about coasting, that get's closer to what I'm asking about. So, you said it "sort of" coasts. Well, I wonder is it literally coasting, when you're on Standard regen mode, and you've feathered that pedal to get the regen guage right in between, so there's no regen green line and no "using battery" black line? If so, then perhaps problem solved, or question answered, at least in part. At least at that equilibrium you're not using any energy, it seems.

Because it seems to me what's really happening in "standard" (higher) regen mode, is that you're actually having to put energy into the rotor/motor, which is set for more resistance in standard mode, so that you have to overcome that regen resistance in order to get the car to move. In a sense, you're using battery energy to turn the rotor, which is harder to turn because you've set the regen higher, but you're actually simultaneously returning energy to the battery because, well because you're regenerating at the same time. The car doesn't move forward until you've put more energy into turning the rotor than the regen resistance.

Another way to cut through all this, is to say, simply, this: I like the feeling of coasting in my car. It's fun to me. I also like recapturing energy, and boosting range (or at least minimizing range loss). So I'd like to coast when I let off the accelerator, and I'd like to regen when I brake.

I can't do that in this car. It's either all regen all the time, or it's Coast and mostly use your brake pads.

I'm also not ever giving up the car because I love it more than any car I've ever owned (or leased). And it's because I love it that I wonder about stuff like the above. Just wondering why Tesla didn't go with an option where you could coast when you wanted to coast (or at least mostly coast) and regen when you wanted to (like when you needed to slow down). That's all.


----------



## fsKotte

garsh said:


> fsKotte, you are *really* misinterpeting what your Leaf is doing.
> 
> When you take your foot off the accelerator, you are regenning (unless your battery is as bad as mine, then you might be coasting). If you want to coast, you leave your foot on the accelerator part way so that there is only one central bubble on the power graph.
> 
> 
> 
> 
> 
> 
> 
> 
> Sure. But the problem is, when you hit the brake pedal, you're not only getting regen, but you're also getting frictional braking at the same time. So you're wasting a portion of that energy as heat in the brake pads. And when you press the brake pedal more, you do get a little more regen, but you get a LOT more frictional braking. It's inefficient.
> 
> With a Tesla, when you want more braking, you just let off of the accelerator more. Tesla provides a LOT more regen than Nissan does. And if that's not enough to slow you down, then (and only then) do you hit the brakes and waste energy as heat in the brake pads.


The Fiat 500e, at least as I understood it, as it's been advertised and reported on, did not use any pads when braking until around 8 mph. Above that your braking was 100% regen (except if you slammed 'em in an emergency stop). So that's different than your Leaf (and I guess, the Leaf I owned for four months, though it sounds like we had similar batteries  ).

As I said, I like to coast sometimes, without having to keep pressure on the pedal, and then when I need to slow down, I'd like for it to be regenerating *fully* and not using pads, like my other EV, unless I'm slamming on the brakes in an emergency.

And the whole point of my OP is that I'm must wondering why it is that in Low regen mode (that regen being only the regen that occurs when you release pressure on the accelerator pedal) your braking doesn't also activate the regen, at all.


----------



## garsh

fsKotte said:


> And the whole point of my OP is that I'm must wondering why it is that in Low regen mode (that regen being only the regen that occurs when you release pressure on the accelerator pedal) your braking doesn't also activate the regen, at all.


I think the answer is two-fold:

It's simpler. Brake pedal only controls hydraulic brakes.
And it's not worse than blended braking in any way. Some like it better - others like blended better.
Peoples' personal preferences can differ, but I don't think anybody can provide an argument that one way is demonstrably better than the other. So in that case, Tesla chooses to stick with their simpler system.


----------



## Kbm3

fsKotte said:


> I just learned that my M3 (as I believe all Teslas) does not use any regen when I apply the brake pedal.
> 
> This surprised me, as I've had previous EV's that do use some regen when you hit the brake pedal, and I found it to be pretty efficient in utilizing the battery (coast and use no/less energy when you could, and then always use regen when you needed to scrub some speed, via "brake" pedal).
> 
> Anybody know why Tesla has chosen to not use any additional regen when you hit the brake pedal? This is interesting to me because I always thought the most efficient way to drive an EV would be to have the ability to coast when you can, and then regain some energy via regen when you need to slow down. I get that "One Pedal" driving can be fun, but I don't get how it's more efficient, when the regen is always on, and so you're never coasting, always applying energy/electricity to keep the car moving . . . .
> 
> I'm sure I'm missing something here, so appreciate any enlightenment. . . .





garsh said:


> It's simpler. The brake pedal just operates the hydraulic brakes.


In performance terms, having the brake pedal blended provides worse brake "feel" according to the car magazines. I guess the deceleration is not quite as linear?

You are correct that a coasting mode would provide the optimal efficiency. Iirc there is one EV that has a detent on the accelerator where you can use feel to hit the coasting point.


----------



## fsKotte

garsh said:


> I think the answer is two-fold:
> 
> It's simpler. Brake pedal only controls hydraulic brakes.
> And it's not worse than blended braking in any way. Some like it better - other's like blended better.
> Peoples' personal preferences can differ, but I don't think anybody can provide an argument that one way is demonstrably better than the other. So in that case, Tesla chooses to stick with their simpler system.


Right, ok. But it doesn't have to be blended braking. It wasn't in my 500e, it was 100% regen until 8mph. I felt that was a good system (using brakes only at 8 mph or under really minimizes wear on them).

I'm also not convinced that brakes also controlling regen would be so complicated that it's undesirable. I'd be interested to know Tesla's thoughts on why they chose to go that way. We can speculate that it was because it was simpler, and that may well literally be why they did it the way they did. Or they could have other reasons that would be interesting to know, which other reasons I'd love to know.

I also think that actually there are arguments being made both for and against "high" regen settings (one pedal driving) versus a coast / regen braking when it comes to which is more efficient. And I find that question interesting. After all, with a Tesla, one component of why it's such a great vehicle is its efficiency. So a debate about what is the most efficient way to drive the car is right up Tesla and its owners' alley(s).

In terms of that particular argument/debate, perusing the forums reveals that it seems there is a consensus that your range is increased via the one-pedal / high-regen setting, versus the low setting (and if range is increased, clearly you're being more efficient). At first, I thought that this conclusion was wrong, but now that I understand there is no regeneration activated by depressing the brake pedal, I think that's probably correct,. But if you had the option to mostly coast when you let off the accelerator, and then regen a lot when you depressed the brake, well then that I think would be a closer call.


----------



## garsh

Kbm3 said:


> In performance terms, having the brake pedal blended provides worse brake "feel" according to the car magazines. I guess the deceleration is not quite as linear?


Correct, it's not very linear. The worse part with the leaf, is that if you're holding down the brake and slowing, at some point when the speed gets low enough, the regen stops. It feels like the brakes have suddenly stopped working to some degree. At that point, you have to push the brake pedal a little harder.

It's not horrible, but it is a little annoying. And definitely non-linear.

The worst is when you're braking down a steep road to just maintain speed, and you hit a pothole or other bump. The ABS kicks on for a second. When that happens, the car turns off regen altogether. It wouldn't be so bad, except the regen stays off until you take your foot off the brake pedal. So the end result is that whenever you hit a bump on a steep downhill, the car begins to accelerate. NOT AT ALL the type of behavior you want in that situation.


----------



## fsKotte

Kbm3 said:


> In performance terms, having the brake pedal blended provides worse brake "feel" according to the car magazines. I guess the deceleration is not quite as linear?
> 
> You are correct that a coasting mode would provide the optimal efficiency. Iirc there is one EV that has a detent on the accelerator where you can use feel to hit the coasting point.


Yes, to me that is the most convincing reason not to include regen in braking, though it seems to me this is an engineering problem that might be solvable. Still, as it stands today, even my Fiat 500e, which had 100% regen until very low speed, definitely had grabby brakes and could have stood to have a smoother "braking curve."

I find the Volt Gen 2 solution to maybe be a good middle ground - on that car, you can set it to low regen mode, but there is a paddle on the wheel that adds additional regen when pressed. The driver can then choose to add additional regen resistance when appropriate, and it also relieves the engineers from having to incorporate it into the braking mechanism (the brake stays being mostly, if not completely, an old-fashioned hydraulic one).

This sort of thing, if available in some form on the M3, seems to me to be a great solution.


----------



## fsKotte

garsh said:


> Correct, it's not very linear. The worse part with the leaf, is that if you're holding down the brake and slowing, at some point when the speed gets low enough, the regen stops. It feels like the brakes have suddenly stopped working to some degree. At that point, you have to push the brake pedal a little harder.
> 
> It's not horrible, but it is a little annoying. And definitely non-linear.
> 
> The worst is when you're braking down a steep road to just maintain speed, and you hit a pothole or other bump. The ABS kicks on for a second. When that happens, the car turns off regen altogether. It wouldn't be so bad, except the regen stays off until you take your foot off the brake pedal. So the end result is that whenever you hit a bump on a steep downhill, the car begins to accelerate. NOT AT ALL the type of behavior you want in that situation.


Yes, I agree, and my 500e also had an uneven "braking" curve, and was pretty grabby - too grabby.

I also responded to Garsh about the Volt Gen 2 model. I think it offers a solution that would meet both of our concerns/positions. That Gen 2 Volt (and I believe it was first introduced on the Cadillac version of the Volt, the ELR) has a paddle on the wheel where you can press it to increase regen resistance, separate and apart from the brake. That would solve/alleviate my concerns, actually, almost completely. It would keep the brake system simple - could be all hydraulic - but it would enable one in "low" regen mode to increase regen when needed without having to completely switch over to the "one pedal" regen mode.

And maybe, since regen mode is a "software" controlled switch on Tesla, you could have a Volt Paddle-like feature enabled via OTA, setting one of the steering button directions to have that same effect (love the OTA stuff!).


----------



## msjulie

> The Fiat 500e, at least as I understood it, as it's been advertised and reported on, did not use any pads when braking until around 8 mph


I had one, I'll support that statement except when/if there's need for a panic stop - then you'll feel the car 'realize' that you want all the braking right now and the hydraulic brakes come right on.

I agree with some that being able to totally shut off regen could be a useful option for some, our A3 e-tron hybrid defaults to that behavior and uses some form of blended braking otherwise. That car is also 'clever' - on a long grade, if you apply the brakes to slow for some magic amount of time, the car will then continue to add regen to try and maintain that speed so you don't have to keep your foot on the pedal. Also manual downshifting of the auto tranny engages some amount of regen as well.

Personally I like the fact that the 3 gives full regen (or to it's configured setting anyway) when you take your foot off the throttle. It's a more straightforward implementation of the braking system to just apply hydraulic brakes based on pedal input vs blending in available regen. When I first got the Tesla, being used to the Fiat, I had a different opinion but I find this method to be much more predictable after getting used to it pretty quick


----------



## garsh

fsKotte said:


> I'm also not convinced that brakes also controlling regen would be so complicated that it's undesirable.


I personally don't desire it. It is undesirable to me. I've lived with it for 6 years. i've gotten used to blended braking, but I don't like it.

Like I said - it's personal preference.


> In terms of that particular argument/debate, perusing the forums reveals that it seems there is a consensus that your range is increased via the one-pedal / high-regen setting


The only situation where it should make a difference is when you need to slow down quickly. In that case, a low-regen setting means you have to use the friction brakes, thereby wasting some energy instead of recovering some of it. Other than that, it shouldn't make a difference.

For efficient driving, it's always best to avoid accelerating and decelerating quickly.


----------



## garsh

fsKotte said:


> I also responded to Garsh about the Volt Gen 2 model. I think it offers a solution that would meet both of our concerns/positions. That Volt (and I believe it was first introduced on the Cadillac version of the Volt, the ELR) has a paddle on the wheel where you can increase regen resistance, separate and apart from the brake. That would solve/alleviate my concerns, actually, almost completely.


I've never driven the Volt, but I agree that Chevy's "paddle" solution does offer some advantages as far as controlling the regen compared to a Tesla.


----------



## msjulie

> _In terms of that particular argument/debate, perusing the forums reveals that it seems there is a consensus that your range is increased via the one-pedal / high-regen setting_




I took a class about e-car building, etc and we were presented info from a study - regen was found to only increase range when the road course called for actual braking. The point was that recapturing energy on downhills did not recover more energy than letting the car speed up more on the downhill while coasting. Seems obvious I guess that you never recapture what it cost to get moving 100%

Regardless, 1 pedal driving is great and I love that I'm not wearing the brake pads down nearly as much as otherwise...


----------



## Blee

Great thread. Am I understanding that when the accelerator is released on th M3, regent starts, then when the brake pedal is depressed regent stops? Or does regen continue and the brakes work separately adding friction resistance through the brake pads. I’ve had this question since the consumer reports evaluation. I was surprised, assuming that there would be two systems simultaneously working to bring the car to a stop.


----------



## garsh

Blee said:


> Great thread. Am I understanding that when the accelerator is released on th M3, regent starts,


Regen begins sooner than that. Regen is at its maximum when you completely release the accelerator.


> then when the brake pedal is depressed regent stops? Or does regen continue and the brakes work separately adding friction resistance through the brake pads


It's the latter. Regen continues as you press the brake pedal.


----------



## Blee

garsh said:


> Regen begins sooner than that. Regen is at its maximum when you completely release the accelerator.It's the latter. Regen continues as you press the brake pedal.


Thanks. That adds to my surprise on the lackluster breaking distance. You would think there would be a distinct advantage built in.


----------



## garsh

Blee said:


> Thanks. That adds to my surprise on the lackluster breaking distance.


The braking distance issue was due to bad ABS calibration. It has since been fixed by an OTA update.

But also, braking distance has little to do with regen. Panic braking performance is due to the physical brakes, pads, and the ABS system that controls them at the limit.


----------



## DXF

msjulie said:


> I took a class about e-car building, etc and we were presented info from a study - regen was found to only increase range when the road course called for actual braking. The point was that recapturing energy on downhills did not recover more energy than letting the car speed up more on the downhill while coasting. Seems obvious I guess that you never recapture what it cost to get moving 100%


This is depends on the height of the "hills" in question. If you get into say the Rockies you're dealing with hills (that the rest of the country would call mountains) where it's not really a good idea. You'll be slowing down a lot, so time's a issue, and you'd be pushing a lot of wind and probably driving at unsafe speeds due to the drastically reduced braking distance of high grade slopes. Basically, you should be modestly braking the whole way down. Which the Model 3 will with just normal 1-pedal mode. It'll handle %15 grade no problem without using the friction braking because, at least the testing I've seen, the standard regen pulls about 0.16G. The % of the slope is directly a match to the % of 1G that you'd accelerate naturally down the slope.


----------



## garsh

DXF said:


> This is depends on the height of the "hills" in question.


Yes, you are of course correct. Don't speed excessively just for efficiency's sake. Safety is more important.

The basic rule is:

Friction brakes are least efficient. All kinetic energy is just converted to heat.
Regen is better, because it captures some (~60%) of that otherwise wasted kinetic energy
Coasting is best as you keep all of that kinetic energy
Caveat: unless you're going fast enough that aerodynamic losses dominate (150+ mph). Slow down.


----------



## Kbm3

garsh said:


> The braking distance issue was due to bad ABS calibration. It has since been fixed by an OTA update.
> 
> But also, braking distance has little to do with regen. Panic braking performance is due to the physical brakes, pads, and the ABS system that controls them at the limit.


Panic one time braking distance is only a function of ABS and tires (I've learned recently from TMC forums). Any modern disc brake is plenty capable of driving the tires to their traction limit. Performance brakes only make a difference in repeated very hard stops. I.e. racetracks.

Interestingly, Elon said regen on the AWD vehicle's will be capable of braking force enough to ride the tire traction limit on the 18's. I wonder how that will be implemented?


----------



## garsh

Kbm3 said:


> Panic one time braking distance is only a function of ABS and tires (I've learned recently from TMC forums). Any modern disc brake is plenty capable of driving the tires to their traction limit. Performance brakes only make a difference in repeated very hard stops.


The "lackluster braking performance" discovered by Consumer Reports occurred in a "repeated panic stops" testing situation.


----------



## DXF

garsh said:


> The "lackluster braking performance" discovered by Consumer Reports occurred in a "repeated panic stops" testing situation.


What it seems like from the bits I've gathered is that the ABS algorithms were designed for normal "real world" use and that the testing environment is an atypical input that lead the systems automatic re-calibration to make poor choices. It's sort of the inverse of the technique of cheating by designing to the review benchmarks.


----------



## Enginerd

I'm not sure I see strong evidence for or against the OP's assertion so far in this thread. Consider one possible advantage of disabling the regen during hydraulic braking: to allow the ABS to do its job. In a slippery ice situation, regen by itself might generate enough torque to cause a wheel to start to slip. If regen is disabled, then the ABS has _full_ authority over wheel slip. With regen, ABS authority would be slightly more limited.


----------



## Maevra

Enginerd said:


> I'm not sure I see strong evidence for or against the OP's assertion so far in this thread. Consider one possible advantage of disabling the regen during hydraulic braking: to allow the ABS to do its job. In a slippery ice situation, regen by itself might generate enough torque to cause a wheel to start to slip. If regen is disabled, then the ABS has _full_ authority over wheel slip. With regen, ABS authority would be slightly more limited.


Good point! Tesla actually does mention that strong regen may cause slippage in icy conditions for this very reason, so guess that's one more plus for the not having regen on hydraulic braking.


----------



## Kbm3

garsh said:


> The "lackluster braking performance" discovered by Consumer Reports occurred in a "repeated panic stops" testing situation.


The problem even occurred the next day. And it was fixed by removing a bug in the ABS calibration software.

My point is that better brakes do not have any effect whatsoever on stopping distances (panic or otherwise) in normal driving, only at the track.


----------



## GregRF

fsKotte said:


> Because it seems to me what's really happening in "standard" (higher) regen mode, is that you're actually having to put energy into the rotor/motor, which is set for more resistance in standard mode, so that you have to overcome that regen resistance in order to get the car to move. In a sense, you're using battery energy to turn the rotor, which is harder to turn because you've set the regen higher, but you're actually simultaneously returning energy to the battery because, well because you're regenerating at the same time. The car doesn't move forward until you've put more energy into turning the rotor than the regen resistance.


You are way over thinking this. The accelerator position is just an electronic input. The motor controller will either be in regen or power mode, at no point is it fighting itself. Low regen will only give you less regeneration all of the time you are off the accelerator, even when braking. In either mode you will have to keep a minimal throttle position to try and "coast" where you try to hit that sweet spot with minimal power or regeneration.


----------



## GregRF

garsh said:


> The worst is when you're braking down a steep road to just maintain speed, and you hit a pothole or other bump. The ABS kicks on for a second. When that happens, the car turns off regen altogether. It wouldn't be so bad, except the regen stays off until you take your foot off the brake pedal. So the end result is that whenever you hit a bump on a steep downhill, the car begins to accelerate. NOT AT ALL the type of behavior you want in that situation.


The Prius would do something similar with the blended brake. Hit a bump on a downhill and regen would stop and it would take a moment for the friction brakes to kick in. For a brief moment it feels out of control and your heart jumps into your throat. Largest problem is that this exact scenario occurs on our road about a quarter mile from our house and it was the wife's car so I would only drive frequently enough to forget about this little issue until my next minor heart attack.


----------



## Enginerd

GregRF said:


> The Prius would do something similar with the blended brake. Hit a bump on a downhill and regen would stop and it would take a moment for the friction brakes to kick in. For a brief moment it feels out of control and your heart jumps into your throat.


I know this exact feeling in my Prius, but I'm fairly certain it's all ABS and not the regen. The regen is so weak in the Prius, and it's effectively nil below 20 mph. I'm pretty sure you wouldn't notice if it wasn't working at low speed. There's a place where I hit a pothole right before exiting a parking lot. When the front wheel hits it, I think the ABS takes charge and removes all braking for a fraction of a second. It's pretty shocking when it happens. First time, I thought I got rear-ended.


----------



## John

Enginerd said:


> I know this exact feeling in my Prius, but I'm fairly certain it's all ABS and not the regen. The regen is so weak in the Prius, and it's effectively nil below 20 mph. I'm pretty sure you wouldn't notice if it wasn't working at low speed. There's a place where I hit a pothole right before exiting a parking lot. When the front wheel hits it, I think the ABS takes charge and removes all braking for a fraction of a second. It's pretty shocking when it happens. First time, I thought I got rear-ended.


Yeah, we've owned 3 Priuses (Prii?) and the ABS software-in my opinion, at least for model years 2008, 2009, the best years-is janky and scary at times. Any time a wheel is jarred by a bump or pothole, breaking is effectively disabled for a second or two. No bueno.


----------



## Sealander

A friend just drove his model S 100D up Pikes Peak yesterday. He said he used 30% of the battery getting to the top and regained 10% when he got back to the bottom. I would have expected more than 10% to be added back during the decent, but regen must have been doing most of the deceleration on the way down because his brake temperature at the checkpoint on the way down was only 77 degrees.


----------



## fsKotte

GregRF said:


> You are way over thinking this. The accelerator position is just an electronic input. The motor controller will either be in regen or power mode, at no point is it fighting itself. Low regen will only give you less regeneration all of the time you are off the accelerator, even when braking. In either mode you will have to keep a minimal throttle position to try and "coast" where you try to hit that sweet spot with minimal power or regeneration.


Not sure if I'm really over-thinking it actually. The electronic input isn't behaving like a binary switch. It isn't regen ON or regen OFF.

Instead, it's behaving like a rheostat, where the regen is increased/decreased depending on how much pressure you're putting on the pedal. This effect is borne out by the many folks who talk about "feathering" the accelerator to modulate their speed. This is clearly evident when you're in "one pedal" mode. If you're going a certain speed, and you *slightly* pull back on the accelerator input, the car slows a little, and regen is a little. But if you totally take your foot off the accelerator, then the regen kicks in very severely and it's like you've put on the brakes suddenly, and the green regen bar goes farther out.

So, either the regen resistance is being modulated, or regen resistance is constant and the balance between your battery power going to turn the rotor is being offset by the regen resistance, and the modulating of the pedal is simply altering that balance by modulating the amount of power being used to try to turn the rotor. Your modulating the amount of battery power you're putting into the system is being offset by the regen resistance. From how the car is behaving in "one pedal" mode when I drive it, this seems to be what's happening.


----------



## garsh

fsKotte said:


> So, either the regen resistance is being modulated, or regen resistance is constant and the balance between your battery power going to turn the rotor is being offset by the regen resistance, and the modulating of the pedal is simply altering that balance by modulating the amount of power being used to try to turn the rotor. Your modulating the amount of battery power you're putting into the system is being offset by the regen resistance. From how the car is behaving in "one pedal" mode when I drive it, this seems to be what's happening.


Your explanation makes it sound like there are two opposing forces - power turning the rotor, and "regen resistance". This is not true. The motor is either generating power, or it's receiving power. At no point in time is the battery both putting power into the motor, AND accepting power from regen. It's one or the other.


----------



## fsKotte

garsh said:


> Your explanation makes it sound like there are two opposing forces - power turning the rotor, and "regen resistance". This is not true. The motor is either generating power, or it's receiving power. At no point in time is the battery both putting power into the motor, AND accepting power from regen. It's one or the other.


I'm not making it sound like that - I'm exactly saying that. (I'm not saying I'm correct, but I am saying that's what I'm saying - if that's not confusing in and of itself!).

I may be wrong about all that, but I'm just trying to understand the situation here, because it's not *behaving* like an all or nothing regen situation, so far as I can tell.

And here's an example: When not being used, the accelerator pedal is at position "0". Then, you get in the car, and let's say you press that pedal, to some forward point (0 + 2 inches forward, say) the car goes forward, and accelerates until it gets to a speed that's constant/consistent with pedal at position zero plus 2". So now you're moving forward at some speed. You then release some pressure on the accelerator but not *all* pressure (so it goes back from 0+2" to, say, 0+1"). Going from 0+2" down to 0+1", you're still pressing on the accelerator pedal, it's not at zero position, but you're going to generate regen when you go from 2" down to 1" pressed. Your green bar will jump out when you do this, then settle down as the system reaches a new equilibrium at 0+1". But it seems that you're also still applying energy to the motor because you're still pressing down to some degree on the accelerator, and you're still going forward as a result. It's acting like a rheostat, essentially.

So you don't only get regen when you completely let off the accelerator; you get varying degrees of regen at *any* time you simply/slightly let-off (but not necessarily fully let off) the accelerator, and depending on your speed at the moment you merely let off the pedal a bit. But you slow down from one speed to a slower speed, and you never fully let go of the accelerator pedal. So when you deccelerate like that, you are getting regen while the accelerator pedal is still being pushed forward to some degree.

So . . . If you're in one-pedal driving mode (high-regen), and you're going 65 mph, and then you let off the accelerator a little and ease on down to 55, is the motor in full regen mode or not, during that deceleration? If you "feather" the accelerator pedal back a bit to slow down that 10 mph, you're obviously not getting the full force and effect of what the regen could do (which is what you'd get if you suddenly fully took your foot off the pedal entirely).

A third way of looking at this puzzle (to me it's a puzzle at least), is: As you go up and down in speed on the highway, for instance, you'll see regen occur as you go from a higher speed to a lower speed, BUT your accelerator pedal the ENTIRE time is still pressed down, to some degree. So what state is the motor in, when you decelerate from a higher speed to a slightly slower speed, all the while with you pressing the accelerator pedal down/forward to some degree the entire time.


----------



## DXF

fsKotte said:


> I just learned that my M3 (as I believe all Teslas) does not use any regen when I apply the brake pedal.
> 
> This surprised me, as I've had previous EV's that do use some regen when you hit the brake pedal, and I found it to be pretty efficient in utilizing the battery (coast and use no/less energy when you could, and then always use regen when you needed to scrub some speed, via "brake" pedal).
> 
> Anybody know why Tesla has chosen to not use any additional regen when you hit the brake pedal? This is interesting to me because I always thought the most efficient way to drive an EV would be to have the ability to coast when you can, and then regain some energy via regen when you need to slow down. I get that "One Pedal" driving can be fun, but I don't get how it's more efficient, when the regen is always on, and so you're never coasting, always applying energy/electricity to keep the car moving . . . .
> 
> I'm sure I'm missing something here, so appreciate any enlightenment. . . .


The reason is most likely to avoid a common issue with hybrids and plug-in EVs that have regen activated on the brakes, the poor control and feedback to the driver. This is sometimes called a "fishy" brake feel. Basically adding regen to the brake pedal almost necessarily increases the travel length of the pedal to achieve the braking and the results are far more inconsistent from use to use, making it harder for the driver to have quick, precise control of the braking.


----------



## GregRF

Try to think of the accelerator as a torque controller that goes from -3 to +10. Negative 3 when you lift completely off, depress a small range to get to zero torque and mash it to the floor to get full torque.


----------



## fsKotte

GregRF said:


> Try to think of the accelerator as a torque controller that goes from -3 to +10. Negative 3 when you lift completely off, depress a small range to get to zero torque and mash it to the floor to get full torque.


OK, a torque controller. Torque is still a form of energy - turning force. Garsh raised an interesting (to me) idea that the motor in the car cannot be both a motor (using energy) and a generator (making energy) at the same moment in time. At any given moment, it is either a generator, or it is a motor. I'm no electrical engineer, or electrician, so I can't say whether that's the case or not, so I'll just accept Garsh's assertion that a motor cannot simultaneously be in a resistance/generation mode and in a "go" mode.

So how, then, does one "coast" with one-pedal driving? You're going 65 miles an hour on the freeway, on flat ground, say, and if you feather the accelerator pedal just right, you can get your energy bar to stay at "zero" - no green regen bar, and no black electricity use bar. It's exactly at "zero" energy use/regen, and yet you're clearly putting energy from the battery in the system, because your car is steadily staying at 65 mph.

In the above example of one-pedal equilibrium, then, what state is the motor? All regen, or all motor? Is it just simple wind resistance and road friction, then, at that equilibrium? Seems unlikely that would account for all of it. I do know that, when you're at that equilibrium point, going in my example 65 mph, and you even slightly let off the accelerator (not fully, just a touch), you'll *instantly* see regen. It seems (not saying it's literally the case, but certainly it gives this effect) that the resistance was there all the while, but you've been inputting enough energy from the battery to overcome the regen resistance and keep it at a steady state of 65 mph, so that as soon as you slightly ease off, that equilibrium shifts to a certain amount of regen.


----------



## GregRF

fsKotte said:


> OK, a torque controller. Torque is still a form of energy - turning force. Garsh raised an interesting (to me) idea that the motor in the car cannot be both a motor (using energy) and a generator (making energy) at the same moment in time. At any given moment, it is either a generator, or it is a motor. I'm no electrical engineer, or electrician, so I can't say whether that's the case or not, so I'll just accept Garsh's assertion that a motor cannot simultaneously be in a resistance/generation mode and in a "go" mode.
> 
> So how, then, does one "coast" with one-pedal driving? You're going 65 miles an hour on the freeway, on flat ground, say, and if you feather the accelerator pedal just right, you can get your energy bar to stay at "zero" - no green regen bar, and no black electricity use bar. It's exactly at "zero" energy use/regen, and yet you're clearly putting energy from the battery in the system, because your car is steadily staying at 65 mph.
> 
> In the above example of one-pedal equilibrium, then, what state is the motor? All regen, or all motor? Is it just simple wind resistance and road friction, then, at that equilibrium? Seems unlikely that would account for all of it. I do know that, when you're at that equilibrium point, going in my example 65 mph, and you even slightly let off the accelerator (not fully, just a touch), you'll *instantly* see regen. It seems (not saying it's literally the case, but certainly it gives this effect) that the resistance was there all the while, but you've been inputting enough energy from the battery to overcome the regen resistance and keep it at a steady state of 65 mph, so that as soon as you slightly ease off, that equilibrium shifts to a certain amount of regen.


Your motor controller works by controlling a rotating magnetic field in the outer shell of the motor known as the stator. The part that actually rotates is the rotor. The rotor has steel and magnetic bits in it that are attracted to this magnetic field.

When you are applying positive torque, the magnetic field will rotate in a manner that leads the bits attracted to it giving the rotor power.

When you apply negative torque the rotating magnetic field will lag the attracted bits causing the rotor to try to slow and give you regeneration.

When you apply zero torque the rotating magnetic filed and rotor will spin in unison and give no power and no regeneration.

Does that help you visualize what is happening?


----------



## Tchris

fsKotte said:


> OK, a torque controller. Torque is still a form of energy - turning force. Garsh raised an interesting (to me) idea that the motor in the car cannot be both a motor (using energy) and a generator (making energy) at the same moment in time. At any given moment, it is either a generator, or it is a motor. I'm no electrical engineer, or electrician, so I can't say whether that's the case or not, so I'll just accept Garsh's assertion that a motor cannot simultaneously be in a resistance/generation mode and in a "go" mode.
> 
> So how, then, does one "coast" with one-pedal driving? You're going 65 miles an hour on the freeway, on flat ground, say, and if you feather the accelerator pedal just right, you can get your energy bar to stay at "zero" - no green regen bar, and no black electricity use bar. It's exactly at "zero" energy use/regen, and yet you're clearly putting energy from the battery in the system, because your car is steadily staying at 65 mph.
> 
> In the above example of one-pedal equilibrium, then, what state is the motor? All regen, or all motor? Is it just simple wind resistance and road friction, then, at that equilibrium? Seems unlikely that would account for all of it. I do know that, when you're at that equilibrium point, going in my example 65 mph, and you even slightly let off the accelerator (not fully, just a touch), you'll *instantly* see regen. It seems (not saying it's literally the case, but certainly it gives this effect) that the resistance was there all the while, but you've been inputting enough energy from the battery to overcome the regen resistance and keep it at a steady state of 65 mph, so that as soon as you slightly ease off, that equilibrium shifts to a certain amount of regen.


I understand your question and it is a very interesting one. I think we will need Tesla to weigh in on this one to provide the real answer.


----------



## fsKotte

GregRF said:


> Your motor controller works by controlling a rotating magnetic field in the outer shell of the motor known as the stator. The part that actually rotates is the rotor. The rotor has steel and magnetic bits in it that are attracted to this magnetic field.
> 
> When you are applying positive torque, the magnetic field will rotate in a manner that leads the bits attracted to it giving the rotor power.
> 
> When you apply negative torque the rotating magnetic field will lag the attracted bits causing the rotor to try to slow and give you regeneration.
> 
> When you apply zero torque the rotating magnetic filed and rotor will spin in unison and give no power and no regeneration.
> 
> Does that help you visualize what is happening?


Thanks - Yes, I think that helps me visualize what's happening.

So Torque is the force that either accelerates the rotor's spin, or slows it. And this is manifest when you cause the stator's magnetic field to start to rotate faster than the rotor is turning at that moment (which is essentially the north/south polarity starting to switch faster in the stator), you're applying positive torque and the rotor spins faster to try to catch up to the faster rotation of the magnetic field in the stator. Or, the rotor slows down if the stator's magnetic field begins to rotate more slowly than the rotor's rotation at any given moment (negative torque). And so when the stator's magnetic field and the rotor rotate at exactly the same speed, no acceleration or deceleration occurs - zero torque state.

So then, would it be safe to say that setting your Model 3 to "standard (high) regen is essentially pre-setting the torque on the motor to some level of negative stator lag then, that must be initially overcome to start moving the rotor?

Another way of stating the question, maybe a better way to get at the heart of this:

When you switch your car from "low" to Standard (High) regen, what exactly has changed in the motor, or elsewhere in the car? Exactly what goes on in the drivetrain system (or the motor itself), in order to switch it from a "low" (low regen/resistance) mode to a "high" (or "standard") regen mode?

Is it that torque bias in the stator, or something like that? I don't think it's a mechanical event in the car, but I don't really know what is changing . . . .


----------



## GregRF

fsKotte said:


> When you switch your car from "low" to Standard (High) regen, what exactly has changed in the motor, or elsewhere in the car? Exactly what goes on in the drivetrain system, to switch it from a "low" (low regen/resistance) mode to a "high" (or "standard") regen mode?


The only change would be how the motor controller interprets the signal from the accelerator pedal position. In some manner it remaps the torque setting from the previous example of -3 to +10 to something like -1 to +10.

So the only change the drivetrain sees is the maximum value it is allowed to regenerate at, otherwise it operates the same.


----------



## fsKotte

GregRF said:


> The only change would be how the motor controller interprets the signal from the accelerator pedal position. In some manner it remaps the torque setting from the previous example of -3 to +10 to something like -1 to +10.
> 
> So the only change the drivetrain sees is the maximum value it is allowed to regenerate at, otherwise it operates the same.


Okay, so then indeed you must apply more energy to the motor in a "high regen" setting in order to first overcome that lag bias, before the rotor starts actually rolling forward and applying power, and moving the car . . . . is that right?

And how is the motor operating, in "high regen" mode, in my other example when you're at 65 mph in "equilibrium", and then you ease off the accelerator input (pedal) so that it regens/slows to 55? With the high regen setting, are you actually taking advantage of the lag bias in the stator to slow the rotor to achieve the slower speed/55?


----------



## GregRF

fsKotte said:


> Okay, so then indeed you must apply more energy to the motor in a "high regen" setting in order to first overcome that lag bias, before the rotor starts actually rolling forward and applying power, and moving the car . . . . is that right?


It is not applying power to overcome regen. You just have more regen to reduce before going to positive torque.



fsKotte said:


> And how is the motor operating, in "high regen" mode, in my other example when you're at 65 mph in "equilibrium", and then you ease off the accelerator input (pedal) so that it regens/slows to 55? With the high regen setting, are you actually taking advantage of the lag bias in the stator to slow the rotor to achieve the slower speed/55?


In "high regen" mode you just have more negative torque to play with. You can slow from 65 to 55 with max regen, you can slow with a lesser amount of regen, you can keep regen and power neutral and allow drag forces to slow you down or you can even have positive torque that is less than the drag forces in which case you will slow down over a longer period of time.

It all takes place on a spectrum of torque values. "High regen" just gives you a larger spectrum of negative torque to choose from.


----------



## fsKotte

GregRF said:


> It is not applying power to overcome regen. You just have more regen to reduce before going to positive torque.
> 
> In "high regen" mode you just have more negative torque to play with. You can slow from 65 to 55 with max regen, you can slow with a lesser amount of regen, you can keep regen and power neutral and allow drag forces to slow you down or you can even have positive torque that is less than the drag forces in which case you will slow down over a longer period of time.
> 
> It all takes place on a spectrum of torque values. "High regen" just gives you a larger spectrum of negative torque to choose from.


Okay . . . .I think I'm getting there - thanks for patiently staying with me on this.

So, "high" regen is just setting the motor to let the stator's magnetic field lag further behind the rotation of the rotor at any given time. You're at a certain speed, rotor rotating within the stator's rotating magnetic field, and then you start to lay off the accelerator pedal, which essentially slows the stator's magnetic field's speed of rotation, and the rotor - due to its magnetic attraction to the stator's magnetic field - then has to slow to try to get down to the newly slower speed/rotation of the stator's magnetic field.

And so with "low" regen, the motor is set to not allow the stator's magnetic field to lag very far behind whatever is the current rotational speed of the rotor. But with "high"/standard regen, the stator's magnetic field is allowed to lag further behind the current rotational speed of the rotor, which permits a stronger deceleration of the rotor's speed.

If I have that all mostly right, my only other question is how does this lag in the stator's rotating magnetic field, which then pulls/slows the rotor's rotation down, generate electricity for the battery.


----------



## Twiglett

so - after three pages the TL;DR is . . .
The brake pedal works friction brakes
The accelerator pedal is the electrical faster/slower pedal depending on pedal position in relation to speed.
Sorted


----------



## fsKotte

Twiglett said:


> so - after three pages the TL;DR is . . .
> The brake pedal works friction brakes
> The accelerator pedal is the electrical faster/slower pedal depending on pedal position in relation to speed.
> Sorted


Well . . . Yeah but.

We always knew the brakes were friction only. That was never at issue.

The question was not whether the "acceleration" pedal made the car go fast or slowed it down under "high" regen mode - again we all knew it did that. The question posed was more why it does what it does, less re what does it do.


----------



## Dr. J

This is about the Roadster, and it's from 2007, but it may shed some light on the thinking that went into the first Tesla regenerative braking system:
*The Magic of Tesla Roadster Regenerative Braking*

[mod edit: fixed broken link]


----------



## GregRF

fsKotte said:


> If I have that all mostly right, my only other question is how does this lag in the stator's rotating magnetic field, which then pulls/slows the rotor's rotation down, generate electricity for the battery.


This gets into the physics of induction. When a magnetic field is rotating through wires it induces a current in those wires. So now we are viewing the rotor and its magnetic bits as the rotating magnetic field and the induced current in the stator windings are harvested by the motor controller to put energy back into the battery. You can check out how an alternator works to get an idea of the theorey here.


----------



## fsKotte

Dr. J said:


> This is about the Roadster, and it's from 2007, but it may shed some light on the thinking that went into the first Tesla regenerative braking system:
> *The Magic of Tesla Roadster Regenerative Braking*
> 
> [mod edit: fixed broken link]


Great read - thanks for the link!


----------



## JeffC

Briefly, regen belongs properly integrated on the brake pedal for reasons of ergonomics, safety, and vehicle dynamics. Putting it on the throttle was a hack left over from friend of a friend Alan Cocconi.

Please see: http://www.jeffchan.com/cars/ev/regen-on-throttle.html


----------



## garsh

JeffC said:


> Briefly, regen belongs properly integrated on the brake pedal for reasons of ergonomics, safety, and vehicle dynamics. Putting it on the throttle was a hack left over from friend of a friend Alan Cocconi.
> 
> Please see: http://www.jeffchan.com/cars/ev/regen-on-throttle.html


Disagree.

Safety:

During a panic stop, it is much quicker to remove your foot from the accelerator than it is to remove your foot from the accelerator, move it over to the brake pedal, and start touching the brake pedal. Regen on the accelerator therefore helps immensely during panic stops to get the speed down sooner.
"Trailing throttle oversteer" will not be induced by regen in an AWD car.
"Trailing throttle oversteer" will not be induced at light levels of regen in a RWD car. Definitely turn down the regen when roads are slippery to prevent that however. It would be good if Tesla would use the traction control system to detect this and automatically turn down regen to compensate, but I don't believe they currently do so.
Brake-integrated regen results in unpredictable - and I would argue "unsafe" - behavior in adverse braking conditions. Coming down a steep hill and hitting a bump in my Leaf basically launches the car forward as regen is suddenly completely removed and doesn't return until I lift my foot off the brake pedal entirely. Braking behavior changes when the car decides that it can't regen as much (such as cold weather, or 100%-charged battery). Having the brake pedal only manage the friction brakes keeps braking feel and behavior much more predictable.
All of these points (and the ones you provide) are fairly minor in the big scheme of things. It's mostly a preference, and neither solution is demonstrably better or safer than the other.


----------



## JeffC

garsh said:


> Disagree.
> 
> Safety:
> 
> During a panic stop, it is much quicker to remove your foot from the accelerator than it is to remove your foot from the accelerator, move it over to the brake pedal, and start touching the brake pedal. Regen on the accelerator therefore helps immensely during panic stops to get the speed down sooner.
> "Trailing throttle oversteer" will not be induced by regen in an AWD car.
> "Trailing throttle oversteer" will not be induced at light levels of regen in a RWD car. Definitely turn down the regen when roads are slippery to prevent that however. It would be good if Tesla would use the traction control system to detect this and automatically turn down regen to compensate, but I don't believe they currently do so.
> Brake-integrated regen results in unpredictable - and I would argue "unsafe" - behavior in adverse braking conditions. Coming down a steep hill and hitting a bump in my Leaf basically launches the car forward as regen is suddenly completely removed and doesn't return until I lift my foot off the brake pedal entirely. Braking behavior changes when the car decides that it can't regen as much (such as cold weather, or 100%-charged battery). Having the brake pedal only manage the friction brakes keeps braking feel and behavior much more predictable.
> All of these points (and the ones you provide) are fairly minor in the big scheme of things. It's mostly a preference, and neither solution is demonstrably better or safer than the other.


First, thanks for taking the time and having an open mind to review my comments. I request an open mind in reviewing the below, since for many people this is new information which they have not encountered before and may not fully understand yet.

Agree these issues are technically minor in daily driving. They are not minor in an emergency situation. And they can make a panic stop worse.

It appears that you may not have understood what I was writing about trailing throttle oversteer. Anything that increases deceleration, including regen, can increase trailing throttle oversteer. That's a physical fact due to load transfer from the rear axle to the front axle that happens during deceleration. This load transfer decreases traction at the rear of the car. Again, this is physical fact. Oversteer can be induced in any kind of car, AWD, FWD, or RWD, just as understeer can be induced in any kind of car. Ask any racer.

In case it's not obvious both oversteer and understeer only happen at the extreme limits of adhesion, such as during racing, or an emergency on the street. However it can happen a low speed; contrary to what one might assume, high speed is not needed to reach traction limits. It can even happen in a parking lot.

Properly integrating regen on the brake pedal results in highly predictable overall braking. When done correctly, the transition from regen to friction braking is smooth and imperceptible. Yes, it can be done badly, as the very first Prius did (but none subsequent), but most car makers implement it very well. And yes, it's very difficult engineering to do well.

The latter is probably why Alan did not do it on the T-Zero. As a tiny company with small budgets, he did not have the engineering resources needed. Unfortunately Tesla copied this arguable error.

Many Tesla fans (of which I am definitely one) are not adequately informed about these issues and base their opinions on limited experience of street driving outside of emergencies or racing. Therefore their opinions may be less than fully informed.

Again, I am a huge Tesla fan and a Tesla customer. I am not anti-Tesla in any way, and I only wish the best for Tesla and its wonderful customers. I also wish they would correct this issue. At least make it a selectable option.

I am not a Tesla short seller or current share holder (though I may buy some in future if it falls to less overpriced levels). I am not speculating on Tesla's stock price. I do not intend to ever sue Tesla for anything. I'm glad the Tesla factories are non-union. I very honestly love Tesla and its mission, which is part of the reason I'm buying a Model 3. I want to support them with my very hard earned money.

I also love EVs in general and think Model 3 is by far the best one available, aside from not having regenerative braking properly integrated with the friction brakes. It's all braking function, right? Why can't it all be on the same pedal, as in most other EVs and hybrids?

P.S. In a panic stop it is not "much quicker" to get braking by lifting off the throttle instead of moving the right foot to the brake, if instead *left foot braking* is used. (Also, getting abrupt braking from lifting off the throttle is my major thesis of why this is undesirable, since it can contribute to trailing throttle oversteer, which by the way is a standard racing term.)

I use left foot braking now, and every racer I know also uses left foot braking on cars without a clutch. Racers use left foot braking because it is faster around a race track. If it were slower, they would not use it. They also tend to use left foot braking on the street. It's objectively and subjectively better: faster, smoother, easier (once mastered), more efficient, both on the racetrack and street.

Left foot braking lets you vary throttle and brake infinitely finely from one full extreme all the way to the other. IMO it's by far the best way to drive. It takes some practice to get good at, like anything else, but is definitely worth it.

If you try left foot braking, which I strongly recommend, it will feel odd for the first several days or even weeks. That's totally normal and expectable. After all, you've spent a lifetime using your right foot to brake.

Note also that you won't be able to operate the brake nearly as sensitively with your left foot as your right at first. That's also normal. Don't get frustrated and give up. Stick with it! Eventually you learn to get similar brake feel from your left foot as your right foot and blending throttle from right foot and brake from left foot becomes easy and natural. Again, it may take some time, but be assured, it's worth doing. It's so much better that you won't go back. But give it a full chance.

On a Tesla (or any other EV), you should switch lift-throttle regen to low when using left foot braking.

"One pedal driving" (regen on throttle lift) also provides some of this benefit (within a much lower range of braking power), but confuses braking with acceleration when they are easily separated on separate pedals. Left foot braking offers finer control of the mix, and higher levels of braking since it also engages the friction brakes, up to maximum friction braking. It's better car control.


----------



## garsh

JeffC said:


> I am not a Tesla short seller.


It's a shame that you feel the need to make that kind of proclamation. I'd like to take this opportunity to remind everybody here that it's alright to disagree with how Tesla does things, and to comment on that in these forums. Please do so in a respectful manner as JeffC has done to avoid escalating a disagreement to an argument. You don't have to be a fan of everything Tesla does.



> ...if instead left foot braking is used.


That's an excellent point. I don't know if this old dog can learn that new trick.


----------



## PNWmisty

JeffC said:


> Anything that increases deceleration, including regen, can increase trailing throttle oversteer. That's a physical fact due to load transfer from the rear axle to the front axle that happens during deceleration. This load transfer decreases traction at the rear of the car. Again, this is physical fact. Oversteer can be induced in any kind of car, AWD, FWD, or RWD, just as understeer can be induced in any kind of car. Ask any racer.
> 
> In case it's not obvious both oversteer and understeer only happen at the extreme limits of adhesion, such as during racing, or an emergency on the street. However it can happen a low speed; contrary to what one might assume, high speed is not needed to reach traction limits. It can even happen in a parking lot.
> 
> Properly integrating regen on the brake pedal results in highly predictable overall braking. When done correctly, the transition from regen to friction braking is smooth and imperceptible. Yes, it can be done badly, as the very first Prius did (but none subsequent), but most car makers implement it very well. And yes, it's very difficult engineering to do well.


I have carefully read all of the above and I'll agree, pretty much 100%



> The latter is probably why Alan did not do it on the T-Zero. As a tiny company with small budgets, he did not have the engineering resources needed. Unfortunately Tesla copied this arguable error.
> 
> Many Tesla fans (of which I am definitely one) are not adequately informed about these issues and base their opinions on limited experience of street driving outside of emergencies or racing. Therefore their opinions may be less than fully informed.
> 
> Again, I am a huge Tesla fan and a Tesla customer. I am not anti-Tesla in any way, and I only wish the best for Tesla and its wonderful customers. I also wish they would correct this issue. At least make it a selectable option.


This is where you flip to making unsupported statements. You went from discussing the physics of regenerative braking to calling Tesla's implementation an "arguable error" and calling the opinion of anyone would support Tesla's implementation "less than fully informed". Before you do that, it would be a good idea to clearly verbalize what viewpoint you believe is less than fully informed (and why). Because, up to that point, you didn't make ANY cohesive argument as to why Tesla's implementation is deficient.



> I also love EVs in general and think Model 3 is by far the best one available, aside from not having regenerative braking properly integrated with the friction brakes. It's all braking function, right? Why can't it all be on the same pedal, as in most other EVs and hybrids?


Again, saying Tesla's implementation is different from other cars is not a valid argument as to why it's inferior. Because, obviously, it would have been easy for Tesla to mimic other EV's but they chose not to.



> P.S. In a panic stop it is not "much quicker" to get braking by lifting off the throttle instead of moving the right foot to the brake, if instead *left foot braking* is used. (Also, getting abrupt braking from lifting off the throttle is my major thesis of why this is undesirable, since it can contribute to trailing throttle oversteer, which by the way is a standard racing term.)


Firstly, no one, and I mean no one, is going to use left foot braking in a panic stop. In a panic stop you don't think, you just react. I don't care how many hours you spend on the track or what kind of car you drove, you are going to lift off the accelerator with your right foot and hit the brake.



> I use left foot braking now, and every racer I know also uses left foot braking on cars without a clutch. Racers use left foot braking because it is faster around a race track. If it were slower, they would not use it. They also tend to use left foot braking on the street. It's objectively and subjectively better: faster, smoother, easier (once mastered), more efficient, both on the racetrack and street.


That's true, there are many advantages to using left foot braking to get around a track faster and at the limits of adhesion. But that's not a panic stop and the Tesla Model 3 is not tuned or designed to be used as a race car. There are two reasons I can see why Tesla allows regenerative braking to be turned to "low" where it mimics the throttle behavior of an ICE car. And one is for track use. The other is just to give normal drivers who don't have a lot of experience with regenerative braking the option of having throttle dynamics they are familiar with. You can have the best of both worlds, it's your choice.



> On a Tesla (or any other EV), you should switch lift-throttle regen to low when using left foot braking.


Obviously, if you want to use two footed driving you should switch regen to low. And Tesla offers this option. But 99% of drivers will not switch to left foot braking for everyday driving to work. It's not going to happen. In fact, in normal driving you don't even need to use the friction brakes except the last 3-5 mph to come to a complete stop. In normal driving on the street, the brakes are just not used.



> "One pedal driving" (regen on throttle lift) also provides some of this benefit (within a much lower range of braking power), but confuses braking with acceleration when they are easily separated on separate pedals. Left foot braking offers finer control of the mix, and higher levels of braking since it also engages the friction brakes, up to maximum friction braking. It's better car control.


If you are normally not using the friction brakes, how is left foot braking going to give you "finer control of the mix"? No matter how superior two-footed braking is at the limits of adhesion, there are insurmountable barriers to normal commuters adopting it in ANY significant numbers, and for good reason. There is only benefit when at the limit of adhesion. And that is when slinging a car around a track. In an emergency situation on the street, the computer controlled dynamic stability systems will kick in at lightning speed (faster than any human can react) to ensure that understeer doesn't come back to bite you. No one drives like Mario Andretti on the street. For that reason, you did not convince me that Tesla's implementation of regenerative braking is the wrong implementation for the application. In fact, I would argue it's by far the best way to implement it and they even give you the track option to turn it off.

So what precisely is the problem? Because you have failed to identify a problem or why everyone needs to switch to left-footed braking for their morning commute.


----------



## MelindaV

garsh said:


> That's an excellent point. I don't know if this old dog can learn that new trick.


Ive really only ever done this in automatic rental cars (but not at all intentionally)


----------



## PNWmisty

I will also point out that the title of this thread is incorrect. Because unless you have one foot on the accelerator and one foot on the brake at the same time, the Model 3 does use regen when on the brakes.


----------



## JeffC

garsh said:


> That's an excellent point. I don't know if this old dog can learn that new trick.


To do my best Elon imitation:

I cannot overstate how excellent left foot braking is. Give it a try. You will not be disappointed.

It will feel very strange at first. Definitely takes practice, like months for me. #WorthIt!

It feels like opening the floodgates of braking and accelerating at will, in perfect harmony, using both left and right sides of the brain simultaneously. It's a totally different feeling. Brain wholly integrated with car. #MindMeldWithCar


----------



## JeffC

PNWmisty said:


> I will also point out that the title of this thread is incorrect. Because unless you have one foot on the accelerator and one foot on the brake at the same time, the Model 3 does use regen when on the brakes.


I'm 99.9999% sure Tesla does regeneratve braking only on the throttle and never on the brake pedal. That was visible on the energy histogram displays on Model S and X. It could be visible on the hard to see energy bar meter below the speedometer on Model 3. (Wish they would add an energy graph on Model 3.)

Also, Teslas beep a warning if you engage the brake at the same time as the throttle (I've done that a couple times on both Model S and Model 3), but good left foot braking has only one actually engaged at any given time.


----------



## garsh

JeffC said:


> I'm 99.9999% sure Tesla only does regeneratve braking only on the throttle and never on the brake pedal.


I believe what @PNWmisty is saying is that the full off-accelerator regen remains in effect while you're pressing the brake pedal to add friction braking.


----------



## JeffC

garsh said:


> I believe what @PNWmisty is saying is that the full off-accelerator regen remains in effect while you're pressing the brake pedal to add friction braking.


Thanks, makes sense. Similar end result but not quite the means I'm asking for.  IMO the means does matter.


----------



## JeffC

PNWmisty said:


> I have carefully read all of the above and I'll agree, pretty much 100%


Agree. There was speaking about physical fact. Newtonian physics should not be controversial in our daily understanding.


> This is where you flip to making unsupported statements. You went from discussing the physics of regenerative braking to calling Tesla's implementation an "arguable error" and calling the opinion of anyone would support Tesla's implementation "less than fully informed". Before you do that, it would be a good idea to clearly verbalize what viewpoint you believe is less than fully informed (and why). Because, up to that point, you didn't make ANY cohesive argument as to why Tesla's implementation is deficient.


There I was offering opinions based on those physical facts and human nature, while also clarifying some of the history of how we reached that point. By less than fully informed, I mean that vehicle dynamics is a somewhat obscure topic unknown to most people, how people behave in emergencies _and how it can affect vehicle dynamics_ is also not widely known, and how "one pedal drivng" originated is also not widely known. A more complete history is given in my link: http://www.jeffchan.com/cars/ev/regen-on-throttle.html


> Again, saying Tesla's implementation is different from other cars is not a valid argument as to why it's inferior. Because, obviously, it would have been easy for Tesla to mimic other EV's but they chose not to.


Agree, but I also explain what the weaknesses are in my main document. All design choices have postives and negatives. In my more complete accounting, regen on throttle has more negatives than regen on brake. Tesla saw regen on throttle and thought it was cool, but may not have had a complete understanding of the background, history, or all of the positives and negatives. Or at least they accounted for the positives and negatives differently. And yes, I do disagree with their design decision. I'm allowed to do that. 


> Firstly, no one, and I mean no one, is going to use left foot braking in a panic stop. In a panic stop you don't think, you just react. I don't care how many hours you spend on the track or what kind of car you drove, you are going to lift off the accelerator with your right foot and hit the brake.


Yes and no. Someone who routinely uses their left foot to brake is also likely to use it in an emergency since it's essentially programmed habit. It becomes automatic and instinctive.

As someone who doesn't use left foot braking, you may not understand how ingrained the latter becomes. It's a very different way to drive a car that makes the car much more of an extension of your limbs than using one foot to do all. I would describe it as integrating left and right brain holistically with the car for acceleration and deceleration in a smooth continuum. It's a very different driving experience.

Left foot braking feels VERY different mentally. It's hard to explain in words. It needs to be tried and mastered to have a real understanding of how it's different.


> That's true, there are many advantages to using left foot braking to get around a track faster and at the limits of adhesion. But that's not a panic stop and the Tesla Model 3 is not tuned or designed to be used as a race car. There are two reasons I can see why Tesla allows regenerative braking to be turned to "low" where it mimics the throttle behavior of an ICE car. And one is for track use. The other is just to give normal drivers who don't have a lot of experience with regenerative braking the option of having throttle dynamics they are familiar with. You can have the best of both worlds, it's your choice.


Left foot braking is not only faster on a track. It's also quicker, smoother, more economical of movement and generally better in the very low-G driving we do on the street too.

You are correct that low regen mimics the slowing due to drag of an automatic transmission car in "drive". Creep also mimics the automatic transmission drag that moves a car forward from a stop. Both are ergonmically highly usefully, so it's obviously good they were included.


> Obviously, if you want to use two footed driving you should switch regen to low. And Tesla offers this option. But 99% of drivers will not switch to left foot braking for everyday driving to work. It's not going to happen. In fact, in normal driving you don't even need to use the friction brakes except the last 3-5 mph to come to a complete stop. In normal driving on the street, the brakes are just not used.


I plan to use left foot braking and low regen for normal driving, but traffic aware cruise control and autosteering in bumper to bumper traffic and long road trips. TACC does make maximum use of regen to slow the car. I confirmed this with Tesla.

Also, just because I'm against "one pedal driving" (as implemented) does not mean I don't understand its benefits. I understand exactly what it does, and exactly how Teslas ended up with it. Please don't assume that I don't know. I do. 


> If you are normally not using the friction brakes, how is left foot braking going to give you "finer control of the mix"?


When regenerative braking is integrated with the brake pedal, you activate regenerative braking by pressing the brake pedal. The first portion of the braking is provided by regen. Harder braking and coming to a complete stop are provided by friction brakes. When it's well integrated, the transition between the two is seamless and imperceptible. So you press gradually with your left foot to brake, and you press gradually with your right foot to accelerate. It's VERY easy, intuitive, smooth, quick, etc.

Left foot or left pedal = go slower

Right foot or right pedal = go faster

Simple, right?

Each foot can give exactly as much acceleration and deceleration as wanted, in one smooth continuum from full power to full braking and everything in between. The "everything in between" includes the full spectrum of normal, gentle driving we do every day on the street too.


> No matter how superior two-footed braking is at the limits of adhesion, there are insurmountable barriers to normal commuters adopting it in ANY significant numbers, and for good reason. There is only benefit when at the limit of adhesion. And that is when slinging a car around a track.


Left foot braking is both better on the track and on the street. It's wonderful for gentle driving on the street too. I did not mean to portray it exclusively as a racing technique. It's not.


> In an emergency situation on the street, the computer controlled dynamic stability systems will kick in at lightning speed (faster than any human can react) to ensure that understeer doesn't come back to bite you. No one drives like Mario Andretti on the street. For that reason, you did not convince me that Tesla's implementation of regenerative braking is the wrong implementation for the application. In fact, I would argue it's by far the best way to implement it and they even give you the track option to turn it off.


Yes and no. Highly skilled drivers can easily outpeform computerized traction control, ABS, etc. It's why racers always desire to turn those off on racetracks. Agree less skilled drivers probably benefit from the electronic aids.

A bigger issue is that relying on them can get people into trouble when they are insufficient, even on the street. If electronic stability aids worked perfectly at all times, there would never be any crashes on the street. People sometimes (unintentionally or otherwise) exceed the physical limits of their cars but don't have the skills or knowledge to know what to do when that happens. Electronic driver aids have unfortunately on occasion proven to get them to that point more readily. (This is a well known issue in automotive engineering, but probably not by the general public.) Again, this is not about racing on the street. It's about controlling a car in an emergency.


> So what precisely is the problem? Because you have failed to identify a problem or why everyone needs to switch to left-footed braking for their morning commute.


Please see my full document. In describes exactly what some of the negatives are. http://www.jeffchan.com/cars/ev/regen-on-throttle

P.S. Tesla's blog discussing this topic does acknowledge the viewpoint of regen on brake, as did a personal conversation with a Tesla engineer. Reference: https://www.tesla.com/blog/magic-tesla-roadster-regenerative-braking


> Almost everyone likes the car to regen when you take your foot off of the throttle pedal, but there are some who would prefer the car to coast when you do this. They would prefer the regen to be tied to the application of the brake pedal.


I am firmly in the latter camp, as are a significant portion of engineers within Tesla itself. When I spoke to the Tesla engineer, he estimated about half were in one camp and half in the other.

So other people do understand the issue and take the same position that I do, including many engineers who work at Tesla itself.


----------



## PNWmisty

Jeff, I can appreciate that people are free to prefer different solutions because there can be advantages and disadvantages to both. But the thrust of your argument is the Tesla chose the WRONG approach. It's important to understand that there is no RIGHT and WRONG approaches, there are only DIFFERENT approaches. The decision as to which is BETTER depends upon the application. It's important to remember we are discussing a mass market car here intended to get people to and from their daily tasks and appointments safely and efficiently.

To support your position, you link to an article by a Tesla engineer who worked on the problem. If anything, that engineer actually appears to support the decision Tesla made to integrate regen w/ the throttle. Here's a quote from the link you provided:

"Almost everyone likes the car to regen when you take your foot off of the throttle pedal, but there are some who would prefer the car to coast when you do this."

Obviously, the fact that "almost everyone" likes the regen to be tied to the throttle doesn't make it the best choice because it's not a popularity contest except to the extent that a mass market car must satisfy the consumer or it will fail to be successful in the market. So it's an important consideration, but not the only consideration. If the car fails in the marketplace because of that choice, the choice was the wrong choice. But let's assume the customer is not always right and we can convince them there is something better and get them to adapt and adopt. So, we are back to looking at the other pro's and cons not having to do with consumer preference.

The same Tesla engineer says:

"One day everyone will drive electric cars and regen will be a big part of what will make them fun to drive, efficient, and safe."

We know regen increases efficiency whether it's tied to the throttle or brake but the pertinent point here is that he also claims regen will be a "big part" of what makes cars "fun to drive" and "safe". Now I'm confident that you think regen should be integrated into the brake and that integration should be as seamless as possible between friction braking and regen, the pedal should have good feedback so the driver can sense impending lock-up and not have to concern themselves with whether the braking force is due to regen or friction as this is extraneous information to the task at hand which is modulating the brake. If the integration of regen into the brake pedal is seamless, then how is regen going to be a "big part" of what makes the car" fun to drive" and "safe"? Because if it were linked to the brakes in a seamless manner, the driving experience should be no different than a car with no regen and the safety would not be different either. If anything, safety might be worse because it would take perfect integration to couple the two types of braking and perfection might not be achieved. It's easy with current technology to make a fully progressive brake using just hydraulics.

In other words, I'm baffled why you think this Tesla engineer supports your opinion that regen should be linked to brakes when his statements make it clear he is envisioning regen linked to throttle. When regen is linked to throttle, the brakes (and brake lights) come on the instant your foot lifts off the accelerator which DOES increase safety over a traditional car. And most people that have experienced one pedal driving find it enjoyable. So it's obvious this particular engineer is not supporting your preferred implementation. Of course, that doesn't mean he is right, so we are back to exploring the pros and cons of the two approaches as applied to a car intended to appeal to consumers.



JeffC said:


> By less than fully informed, I mean that vehicle dynamics is a somewhat obscure topic unknown to most people, how people behave in emergencies _and how it can affect vehicle dynamics_ is also not widely known, and how "one pedal drivng" originated is also not widely known.


It's not clear to me what your argument is here. Are you assuming anyone who disagrees with your preferred implementation cannot be fully informed? Or that, because you are fully informed, your preferred implementation is necessarily the best one?



> All design choices have postives and negatives. In my more complete accounting, regen on throttle has more negatives than regen on brake. Tesla saw regen on throttle and thought it was cool, but may not have had a complete understanding of the background, history, or all of the positives and negatives. Or at least they accounted for the positives and negatives differently.


I would NOT assume that "Tesla" (collectively) had a more incomplete understanding of the implications than yourself. After all, you are one person. You know Tesla had the combined experience of many professional drivers and took this decision very seriously. And I'm sure they accounted for the positives and negatives differently than you did because, ultimately, their decisions affect whether the car is a failure or a success. But to think you have a more complete understanding of the background and history of the different implementations of regenerative braking than the combined knowledge of Tesla is probably false.



> Someone who routinely uses their left foot to brake is also likely to use it in an emergency since it's essentially programmed habit. It becomes automatic and instinctive.


That may be but it's irrelevant because, out of the total population of car drivers, less than 1% use their left foot to regularly brake. It would be foolish to tailor the braking to people who comprise less than 1% of your market. In actuality, people who regularly brake with their left foot almost certainly comprise less than 1 person in 1000.



> As someone who doesn't use left foot braking, you may not understand how ingrained the latter becomes.


No, I fully understand that. It is well understood that doing something enough times makes it second nature, ingrained and totally natural. In fact, doing something enough times makes it so natural that it might be difficult to do it any other way without another long training period.



> It's a very different way to drive a car that makes the car much more of an extension of your limbs than using one foot to do all. I would describe it as integrating left and right brain holistically with the car for acceleration and deceleration in a smooth continuum. It's a very different driving experience. Left foot braking feels VERY different mentally. It's hard to explain in words. It needs to be tried and mastered to have a real understanding of how it's different.


But I never argued that braking with the left foot was NOT a very different way to drive or that it was easy to master. I fully appreciate that ingrained movements take a long time to retrain.



> Left foot braking is not only faster on a track. It's also quicker, smoother, more economical of movement and generally better in the very low-G driving we do on the street too.


Tesla is not selling a car tailored to the track so the fact that left foot braking may be faster on the track is completely irrelevant. Your claim that left foot braking is "quicker, smoother, more economical of movement and generally better" on the street is also irrelevant (because people who regularly and naturally brake with their left foot are less than 1 in a 1000).



> I plan to use left foot braking and low regen for normal driving, but traffic aware cruise control and autosteering in bumper to bumper traffic and long road trips. TACC does make maximum use of regen to slow the car. I confirmed this with Tesla.


You are free to drive it however you want. But your claim is that Tesla made the "wrong" decision in coupling regen to the accelerator instead of the brake pedal but you still haven't made a good argument that it's true.



> Also, just because I'm against "one pedal driving" (as implemented) does not mean I don't understand its benefits. I understand exactly what it does, and exactly how Teslas ended up with it. Please don't assume that I don't know. I do.


I'm confused why you ask me not to assume you are ignorant of the benefits of one pedal driving. I don't think I implied that at all. If anything, you are the one who implies I, and most everyone else, are ignorant of the benefits of left foot braking. And that is not the case. But I do not find left foot braking to be necessary for safety, smoothness or any other reason on the street. Situational awareness is key for safety in traffic, not whether you use your left or right foot for braking.



> When regenerative braking is integrated with the brake pedal, you activate regenerative braking by pressing the brake pedal. The first portion of the braking is provided by regen. Harder braking and coming to a complete stop are provided by friction brakes. When it's well integrated, the transition between the two is seamless and imperceptible. So you press gradually with your left foot to brake, and you press gradually with your right foot to accelerate. It's VERY easy, intuitive, smooth, quick, etc.


Correct, this is how a traditional car works. Most of us have decades of experience driving like that.



> Each foot can give exactly as much acceleration and deceleration as wanted, in one smooth continuum from full power to full braking and everything in between. The "everything in between" includes the full spectrum of normal, gentle driving we do every day on the street too.


Why do I get the feeling you are trying to convince me, and everyone else, to switch which foot I brake with? I've been using my right foot to brake since I started driving decades ago. Your contention is that Tesla made the wrong decision in coupling regen to the accelerator but it appears you have to change the way I drive, as well as almost everyone else, in order to make your case? Tesla is trying to sell electric cars, not re-train everyone how to drive. I think they made the right decision. You disagree but don't offer any logical support to your opinion.



> Left foot braking is both better on the track and on the street. It's wonderful for gentle driving on the street too. I did not mean to portray it exclusively as a racing technique. It's not.


You can left foot brake on the street if you want to. I'll continue using my right foot. Especially now that Tesla has coupled regen to the accelerator, it's even more fun. Simply claiming that left foot braking is "wonderful for gentle driving on the street" does not offer any support for your claim that Tesla erred when they coupled regen to the accelerator.



> Yes and no. Highly skilled drivers can easily outpeform computerized traction control, ABS, etc. It's why racers always desire to turn those off on racetracks. Agree less skilled drivers probably benefit from the electronic aids.


WoW! I thought you had a motorsport background and were familiar with what it takes to win races at the highest levels. My primary racing knowledge is in MotoGP (formerly Grand Prix motorcycle racing) because I am a primarily a motorcycle enthusiast, cars are just transportation to me. Electronic traction aides are indispensable to winning MotoGP races. I checked F1 auto racing, same thing.

Your claim that "highly skilled" drivers can easily outperform electronic traction aids is easily disproven by looking at MotoGP and Formula 1 (the two highest levels of road racing, motorcycles and F1 cars). Are you saying the best riders/drivers in the world are not "highly skilled"? In 1994 F1 outlawed electronic traction aids and there was the great cheating controversy (some teams were accused of using electronic traction aids that were outlawed). A little background can be found here: http://www.espn.co.uk/racing/news/story?series=6&id=3273623

There is no doubt that electronic traction aids regularly and reliably outperform the best drivers in the world (contrary to your unsupported claim).



> A bigger issue is that relying on them can get people into trouble when they are insufficient, even on the street. If electronic stability aids worked perfectly at all times, there would never be any crashes on the street.


What? It makes no sense that electronic stability aids could prevent all accidents. Even with full autonomous driving, there will be an occasional accident. Less than human error but not perfect. But electronic traction/stability aids simply assist the driver in maintaining traction and directional control of the car, they don't prevent all accidents even when working perfectly.



> People sometimes (unintentionally or otherwise) exceed the physical limits of their cars but don't have the skills or knowledge to know what to do when that happens. Electronic driver aids have unfortunately on occasion proven to get them to that point more readily. (This is a well known issue in automotive engineering, but probably not by the general public.) Again, this is not about racing on the street. It's about controlling a car in an emergency.


Again, electronic aids do not prevent all accidents, they merely make an accident less likely. And the less skill a driver has, the more they help. You seem to be implying that electronic aids can make an accident more likely.



> Please see my full document. In describes exactly what some of the negatives are. http://www.jeffchan.com/cars/ev/regen-on-throttle


I've read your full document carefully. It does not support your claim that Tesla's decision to couple regen to the accelerator was the wrong decision. You have simply failed to support your claim in any meaningful way. You can have whatever opinion you want but, if you can't support it with facts, in a logical manner, you probably won't convince very many people that you're right and Tesla is wrong.



> P.S. Tesla's blog discussing this topic does acknowledge the viewpoint of regen on brake, as did a personal conversation with a Tesla engineer. Reference: https://www.tesla.com/blog/magic-tesla-roadster-regenerative-braking


That's the link I extracted the quote from the Tesla engineer (at the beginning of this post). He appears to agree with me.



> I am firmly in the latter camp, as are a significant portion of engineers within Tesla itself. When I spoke to the Tesla engineer, he estimated about half were in one camp and half in the other.


It may be half/half, I don't know, but there is room for a lot of doubt about that claim. What is clear is the decision clearly went with those favoring regen on the accelerator. And your argument that the decision Tesla made was "wrong" is pretty much unsupported by anything you have presented. And much of what you have presented is clearly erroneous (which I have detailed above).


----------



## John

Model 3 will bark at you if you contact both pedals at once, so keep that in mind if you plan to drive a Model 3 with both feet.

I'd be pissed—pissed, I tell you—if they removed regeration-on-the-accelerator, because I believe that in day to day driving it's highly useful, and more optimum than putting regen just on the brake pedal. Why swing your foot back in forth when 90% of the time (except at full stops) you can just use one pedal? I'm delighted each time I cruise around a corner with one pedal.

I'd support having the brake pedal preferentially apply regen to preserve the brake pads, if they don't already do that.


----------



## GDN

Seems to be many approaches to this, but I'll say many people avoided electric cars because they didn't go very far on a charge and perhaps because they drove different. I agree that you can take this thing to the nth degree to make it just as efficient as you can, but lets just say you've got to give and make compromises. I've been driving for about 37 years. I figure most of us on this forum have been driving for 20+ years. Changing habits and the way we drive is not simple, and most won't do it, will complain about it and make others think the car is not designed well. 

If you think people are going to learn to drive with a single pedal after driving many years, it's not going to happen, or at least not easily. I'm very thankful that Tesla gives different levels of regeneration. I hate the aggressive one. My partner likes it, but after 4 weeks still doesn't have the hang of it. I'm happy to get some regen over none, but lets face it, driving 310 miles, say a "full charge", even in city traffic and using heavy regeneration - how much do you really capture and reclaim? I figure it has to be minimum. I'll give up regeneration completely and just accept the fact that I'm not paying for gas and am able to charge at home. So take full regeneration if you like it, accept that Tesla has to build a car that needs to convert people coming from gas autos and you can't go 100% to the left and still make that happen. This isn't a leaf, it isn't an Insight, it's a mainstream auto that will convert people that none of the others have been able to do, it has to be in the middle somewhere and Tesla is proving they've done it right with the number they are selling.


----------



## John

GDN said:


> If you think people are going to learn to drive with a single pedal after driving many years, it's not going to happen, or at least not easily.


Took me and my family about a week or two to get fully used to it, and to prefer it.
I've let newbies drive it that took it as a challenge and got good within one long drive.
But I get that some people don't like new things.


----------



## GDN

John said:


> Took me and my family about a week or two to get fully used to it, and to prefer it.
> I've let newbies drive it that took it as a challenge and got good within one long drive.
> But I get that some people don't like new things.


Maybe it is easier than I think, I personally just didn't like it. I've truly gotten old and it just happened over night. I like acceleration, I like to be able to coast a bit if desired and when I want brakes I want to control them with the other pedal. Life may pass me by, but just give me that computer option to keep it old fashioned if I want it that way please.


----------



## John

GDN said:


> Maybe it is easier than I think, I personally just didn't like it. I've truly gotten old and it just happened over night. I like acceleration, I like to be able to coast a bit if desired and when I want brakes I want to control them with the other pedal. Life may pass me by, but just give me that computer option to keep it old fashioned if I want it that way please.


I hear you about the getting old part. I'm feeling that more each day...


----------



## JeffC

PNWmisty thanks very much for your detailed reply. Let me make some brief responses:

1. First, my thesis is definitely an opinion on why regenerative braking should be integrated with the friction brakes. I tried to back it up with an explanation of physical fact, ergonomics, vehicle dynamics and safety science. Anyone is welcome to have a different opinion, however I think I made a very strong case why regenerative braking should be integrated with friction braking at least as a selectable option.

2. I do understand that regenerative braking on throttle lift is beneficial to many people. In fact, it gives many of the same benefits as left foot braking: smoothly integrated braking and acceleration, where the braking is within the fairly low range of normal street driving, and not the high levels of emergency braking or braking for a corner in racing.

Where it may be problematic is if it makes trailing throttle oversteer worse. I believe I made fully cogent and relevant arguments grounded in physics and human factors science. Anyone is free to disagree, but I don't think they can disagree meaningfully with the science, which is both pretty basic and also easily measurable. Scientific theories _can_ be wrong, but these ones very likely _aren't_.

It's also problematic if it trains drivers that typical braking is available on the throttle, but emergency braking is on the brake. Better training would be to use the throttle for acceleration and brake for braking. Can you see how the former could contribute to something human factors scientists call "control confusion," where one control is mistaken another? (As an aside, I have worked on human factors research at NASA.)

3. When I was referring to racers disabling driver aids, I was referring to production street cars taken to race tracks, not purpose built race cars such as Formula 1. (Vastly more people have access to the former than the latter; it's the more common racing experience by far.)

Driver aids for production cars deliberately have relatively low limits in order to have some margin of safety for untrained drivers on public roads; to have some reserves of traction remaining after those limits are exceeded. Racers can definitely outperform this calibration of system found on most street cars. Production cars like Ferrari street cars do have higher limits, but most cars do not. (In fact Ferraris, etc., have adjustable limits, in effect. Again talking about their production cars, not their Formula 1, etc.)

4. I fully agree that electronic driver aids are beneficial to street drivers as described above. However it is also well document that untrained drivers often don't know what to do after those aids are triggered. In that sense, the aids enable the drivers to get into trouble, without having enough skills to get themselves out of it.

5. Yes, the Tesla blog dues support regen on throttle (after all the purpose of the blog appears to be to explain why they selected it), but the same blog also explicitly acknowledges regen on brake as valid.

6. A workable solution would be to add a third setting on the Regen control:

Standard, Low, Regen on Brake

I do understand that this issue is challenging and difficult for some people who have been driving Teslas for a long time. I would urge them to respectfully and thoughtfully consider both sides. Other intelligent and thoughtful people can and do reach other conclusions.


----------



## JeffC

John said:


> Model 3 will bark at you if you contact both pedals at once, so keep that in mind if you plan to drive a Model 3 with both feet.
> 
> I'd be pissed-pissed, I tell you-if they removed regeration-on-the-accelerator, because I believe that in day to day driving it's highly useful, and more optimum than putting regen just on the brake pedal. Why swing your foot back in forth when 90% of the time (except at full stops) you can just use one pedal? I'm delighted each time I cruise around a corner with one pedal.
> 
> I'd support having the brake pedal preferentially apply regen to preserve the brake pads, if they don't already do that.


Responding to your points in order:

Yes, All current Teslas beep a warning if both pedals are pressed at the same time. I am able to left foot brake in Teslas by setting regen to low and being careful to lift off the throttle before pressing the brake, and vice versa. (In reality you take up the slack as much as possible, to minimize the transition time. Both controls have a dead zone where they have no effect.)

Agree one pedal driving is useful for many folks. If regen on brake were made available as a selectable option that would work for me:

Regen: Standard, Low, On Brake

Yes, exactly. Regenerative braking when integrated with the brake pedal always maximizes the use of regen before using (much) friction braking. It definitely prevents most friction brake use and wear in normal street braking. Really it's a different way of organizing the same end result. Where it differs is in how the controls work near the limits of adhesion and/or in an emergency.

(P.S. Does anyone know if there's an easy option in this bulletin board software to inline quote, i.e., respond to one quoted paragraph at a time? I could not find it in their documentation at: https://xenforo.com/community/help/bb-codes/ )


----------



## JeffC

GDN said:


> Seems to be many approaches to this, but I'll say many people avoided electric cars because they didn't go very far on a charge and perhaps because they drove different. I agree that you can take this thing to the nth degree to make it just as efficient as you can, but lets just say you've got to give and make compromises. I've been driving for about 37 years. I figure most of us on this forum have been driving for 20+ years. Changing habits and the way we drive is not simple, and most won't do it, will complain about it and make others think the car is not designed well.
> 
> If you think people are going to learn to drive with a single pedal after driving many years, it's not going to happen, or at least not easily. I'm very thankful that Tesla gives different levels of regeneration. I hate the aggressive one. My partner likes it, but after 4 weeks still doesn't have the hang of it. I'm happy to get some regen over none, but lets face it, driving 310 miles, say a "full charge", even in city traffic and using heavy regeneration - how much do you really capture and reclaim? I figure it has to be minimum. I'll give up regeneration completely and just accept the fact that I'm not paying for gas and am able to charge at home. So take full regeneration if you like it, accept that Tesla has to build a car that needs to convert people coming from gas autos and you can't go 100% to the left and still make that happen. This isn't a leaf, it isn't an Insight, it's a mainstream auto that will convert people that none of the others have been able to do, it has to be in the middle somewhere and Tesla is proving they've done it right with the number they are selling.


Historically, regen on brake is the traditional way to do it, an regen on throttle is the new way. Newer is not always better. There were very sound reasons why engineers and human factors scientists put regenerative braking on the brake pedal on the EV1, Toyota Prius, Nissan Leaf, original Toyota RAV4 EV made by Toyota not Tesla, and many other EVs and hybrids.

Note that EV1 was developed from the Hughes/GM Impact that Alan Cocconi worked on. GM deliberately made the significant engineering effort to integrate regenerative braking on the brake pedal of EV1. And they did it superbly well. The transition between regen and friction braking was seamless. Toyota too on their original RAV4 EV, and eventually on the Prius. (First generation Prius had poor integration of regen and friction on the brake.)

What most people probably don't know is that friend-of-a-friend Alan Cocconi put regen on the throttle probably because he did not have the engineering and financial resources to fully integrate it with the brake pedal. The latter is very hard to do well and requires very significant engineering effort and expense.

Alan's designs were picked up directly by Tesla when they licensed his AC Propulsion technology from the T-Zero for use in the (original) Tesla Roadster, and from thence forward. That's probably how Tesla got regen on throttle.

To take the other side of the argument, it probably is easier for most drivers to use regen on throttle in order to more smoothly transition from acceleration to braking (unless they are using left foot braking) after some familiarization. The Tesla engineer I spoke with mentioned that they had data showing that the efficiency was better with regen on throttle (again presumably for drivers not using left foot braking). I was not able to ask him if those were measured real-world data, and/or data from simulations.

Regen on throttle is the newer way of doing things, and does require some retraining, as GDN mentioned. (Of course I would counter-argue that when regenerative braking is integrated with the brake pedal, no new training is required. Brake pedal = braking. Again, this is much simpler ergonomically, and it's possibly safer in terms of trailing throttle oversteer.)

It's important to consider both sides. I usually try to.


----------



## garsh

JeffC said:


> Let me make some *brief *responses:


<inigo montoya>You keep using that word. I don't think it means what you think it means.</inigo montoya>



JeffC said:


> (P.S. Does anyone know if there's an easy option in this bulletin board software to inline quote, i.e., respond to one quoted paragraph at a time?


I do it manually. First, quote the reply. Then insert quote tags in the middle where you wish to break it up:


Code:


...end of a sentence[/quote]<type your response here>[quote]Beginning of another...




JeffC said:


> What most people probably don't know is that friend-of-a-friend Alan Cocconi put regen on the throttle probably because he did not have the engineering and financial resources to fully integrate it with the brake pedal. The latter is very hard to do well and requires very significant engineering effort and expense.


I agree. But that also results in a simpler system. The simpler system is easier to get correct. And as it turns out, I've found that I prefer Tesla's solution over Nissan's even though I drive a Leaf every day and have only driven a Tesla a handful of times.

And like you said, regen on the brake is very hard to do well. Nissan - for instance - did not do it well. I haven't driven any other EVs that put regen on the brake, so I can't say whether GM handled this any better (and once you get past Nissan and GM, everybody else has compliance cars). I do like GM's idea to put additional regen on a paddle. But I'm one of those weird people who like the idea of having more control over the car, which mostly goes against Tesla's philosophy.


----------



## MelindaV

JeffC said:


> (P.S. Does anyone know if there's an easy option in this bulletin board software to inline quote, i.e., respond to one quoted paragraph at a time? I could not find it in their documentation at:


Highlight text from post to be quoted and click the +quote option. Then in the reply box at the bottom of the page, click insert quotes


----------



## PNWmisty

JeffC said:


> I think I made a very strong case why regenerative braking should be integrated with friction braking at least as a selectable option.


I am not opposed to having it as a selectable option because the only downside would be considerable extra cost, the amount of which would depend upon the volume of people who paid the extra cost. I would even use it from time to time.

But I disagree that you made a strong case that's where it belongs as the default. And I've read your position very carefully. You simply didn't provide any reason why regen on the "one pedal" side is inferior for normal street driving except to say that it induces understeer. But you admit that understeer only happens at the limit of traction and then provided an opinion that computerized controls to deal with that exact situation are somehow inferior to human drivers, at least highly skilled human drivers.Which is demonstratably false. The only reason amatuer racers turn off electronic aids for racing is because the aids on street cars are optimized for maximum safety, not for fastest lap times when racing. Certainly you get this, no?



> 2. I do understand that regenerative braking on throttle lift is beneficial to many people. In fact, it gives many of the same benefits as left foot braking: smoothly integrated braking and acceleration, where the braking is within the fairly low range of normal street driving, and not the high levels of emergency braking or braking for a corner in racing.
> 
> Where it may be problematic is if it makes trailing throttle oversteer worse. I believe I made fully cogent and relevant arguments grounded in physics and human factors science. Anyone is free to disagree, but I don't think they can disagree meaningfully with the science, which is both pretty basic and also easily measurable. Scientific theories _can_ be wrong, but these ones very likely _aren't_.


The problem isn't that your scientific theories are_ wrong_, it's that they aren't applicable to street driving. As I've already pointed out, and you admit, the understeer only happens at the limit of traction. And we have computerized driver aids that deal with this very well, better than any human. The fact that they are optimized to save lives, not get around a track faster is irrelevant to a car designed for street driving. For racing purposes, you can buy a real racing car (or modify a street car for racing).



> It's also problematic if it trains drivers that typical braking is available on the throttle, but emergency braking is on the brake. Better training would be to use the throttle for acceleration and brake for braking. Can you see how the former could contribute to something human factors scientists call "control confusion," where one control is mistaken another?


I disagree that regen on the throttle adds any confusion to where you step in an emergency. Existing drivers already instinctually reach for the brake in an emergency and I don't think learning drivers will be confused either. The reason for this is that regen braking is not strong enough to be confused for anything but gentle braking. Do you think engine braking in a manual transmission causes drivers to get confused as to which pedal to push in an emergency braking situation? In fact, regen on the throttle makes emergency braking safer because the brake lights come on sooner and initial speed is reduced before the driver even has time to get on the brake.

Your only argument to the contrary requires everyone to start using left foot braking like yourself, and that is just not going to happen. So you can't use that to argue that Tesla made a bad decision.



> When I was referring to racers disabling driver aids, I was referring to production street cars taken to race tracks, not purpose built race cars such as Formula 1. (Vastly more people have access to the former than the latter; it's the more common racing experience by far.)
> 
> Driver aids for production cars deliberately have relatively low limits in order to have some margin of safety for untrained drivers on public roads; to have some reserves of traction remaining after those limits are exceeded. Racers can definitely outperform this calibration of system found on most street cars. Production cars like Ferrari street cars do have higher limits, but most cars do not. (In fact Ferraris, etc., have adjustable limits, in effect. Again talking about their production cars, not their Formula 1, etc.)


OK, so you admit that electronic driver aids have two categories. Those designed to provide the highest safety on the street and those designed to provide the absolute lowest lap times on the track. So why is this even an issue? Obviously, a car designed for street use should offer the highest safety and a car for the track should offer the lowest lap times for a skilled driver. Why is this even a point of discussion?



> I fully agree that electronic driver aids are beneficial to street drivers as described above. However it is also well document that untrained drivers often don't know what to do after those aids are triggered. In that sense, the aids enable the drivers to get into trouble, without having enough skills to get themselves out of it.


That's just double-speak. Of course untrained drivers might not know what to do after the driver aids are triggered. Untrained drivers don't even know what to do_ before_ the aid is triggered. And if the aid is not available on their car, they_ still_ don't know what to do before they lose control or after. The driver aid is to reduce the problem. And I disagree that the driver aids "enable" the driver to get into trouble. They are fully capable of getting into trouble_ without_ the electronic aids present. In fact, it is more likely they will get into trouble without the electronic aids, this is what is well documented and relevant to safety.



> Yes, the Tesla blog dues support regen on throttle (after all the purpose of the blog appears to be to explain why they selected it), but the same blog also explicitly acknowledges regen on brake as valid.


I acknowledge regen on the brake is_ a valid_ option, I disagree it's the _best_ option. And I can't see how you've provided any good reasons why it is the best option. I also agree it would be nice if it could be selected in the user settings. But that would require different hardware than what we have currently and more development and the associated higher price. So none of this supports your position that regen should_ only_ be on the brake pedal.



> I do understand that this issue is challenging and difficult for some people who have been driving Teslas for a long time. I would urge them to respectfully and thoughtfully consider both sides.


Honestly, I have very carefully considered everything you've said. And I understand everything you've said. Not all of it is accurate and I've pointed out those instances. I believe you have not made even a weak case why Tesla made the wrong decision and the only reason you believe they did is explained by two things:

1) Your personal preference to brake with only your left foot.
2) Confusion about the differences between cars designed for racing and cars designed for the street (there's a reason we don't use Formula 1 cars to drive to work).

The bottom line is the Model 3 is not a purpose-built race car, that's why regen is on the right pedal (pun intended).


----------



## John

Two related observations:

One of the often appreciated features of a manual transmission car is the ability to control deceleration with the accelerator pedal; this is what I like about "regen on the accelerator"-speed up, slow down, no pedal shuffling or dual-footing

I did catch myself once having momentary confusion when I was using the accelerator to slow to a stop and suddenly pressed it harder to stop faster. No big deal, quickly fixed, but I think I understand how people drive into mini-marts now when they are distracted. You have to be distracted to do this, because your mind has shifted to the need for a brake press before you foot has shifted to the brake pedal. Still, my preferred solution would be regen to full stop (along with *maybe* automatic hold at stop lights and stop signs), rather than eliminating regen on the accelerator.


----------



## JeffC

PNWmisty Thank you again for your reply. It appears that you are not agreeing with or understanding some of what I'm writing. As such, it might be best for us to agree to disagree on those parts. As for your appearing to not understand some of what I wrote, I honestly regret that. Surely the fault is mine for not being a good enough teacher to explain it clearly enough.

The best I can do is to ask people to keep an open mind. I thank you for doing that.


----------



## Twiglett

fsKotte said:


> Well . . . Yeah but.
> 
> We always knew the brakes were friction only. That was never at issue.
> 
> The question was not whether the "acceleration" pedal made the car go fast or slowed it down under "high" regen mode - again we all knew it did that. The question posed was more why it does what it does, less re what does it do.


Actually maybe I should have put TLC
Too long don't care


----------



## JeffC

garsh said:


> I agree. But that also results in a simpler system. The simpler system is easier to get correct. And as it turns out, I've found that I prefer Tesla's solution over Nissan's even though I drive a Leaf every day and have only driven a Tesla a handful of times.


It's sort of apples and oranges. I fully understand the benefits of regen on throttle, and they do exist. It is probably easier for many drivers to brake on the throttle after getting accustomed to it, than to use left foot braking. I find the latter indispensable. Yes, there is a definite learning curve to left foot braking.

I definitely prefer regen on brake for many reasons which I believe are well grounded in vehicle dynamics, human factors and safety science.



> And like you said, regen on the brake is very hard to do well. Nissan - for instance - did not do it well. I haven't driven any other EVs that put regen on the brake, so I can't say whether GM handled this any better (and once you get past Nissan and GM, everybody else has compliance cars). I do like GM's idea to put additional regen on a paddle. But I'm one of those weird people who like the idea of having more control over the car, which mostly goes against Tesla's philosophy.


Tesla definitely tries to simplify, which is generally a good thing, as long as things are not "too simple" to paraphrase Einstein.

Having variable regen using steering wheel paddles is: 1. Very cool. 2. Very usable. 3. An interesting use of a different control. However I would also make a very strong argument that integrating regen with the brake pedal is simpler, easier, and safer to use.

VW puts variable regen on the paddles, simulating some of the effect of gear down****s which are usually operated from those paddles, but they also fully integrate regen on the brake pedal.

So you can regen on a VW EV either by simply pressing the brake pedal, or using the paddles. The brake pedal is both smoother and easier. It's also much better ergonomics and safety since there is one less control to potentially be confused by. In that case, simpler is better.

Like VW and Toyota, GM also integrates regenerative braking with the brake pedal.


----------



## PNWmisty

JeffC said:


> PNWmisty Thank you again for your reply. It appears that you are not agreeing with or understanding some of what I'm writing. As such, it might be best for us to agree to disagree on those parts.


Which specific points that you have already made does it look to you like I'm not understanding?


----------



## JeffC

John said:


> One of the often appreciated features of a manual transmission car is the ability to control deceleration with the accelerator pedal; this is what I like about "regen on the accelerator"-speed up, slow down, no pedal shuffling or dual-footing


Yes, that simulates engine braking (compression braking) to slow a vehicle.

Perhaps ironically, it's using a side effect of an internal combustion engine in an EV.

Some big rig trucks have extremely strong engine braking by also opening the exhaust valves when they compression brake. This turns the very large diesel engine into a very powerful air compressor (actually vacuum pump), and it makes that loud pulsing sound you sometimes hear from trucks when they brake. Not all big rigs have this.




> I did catch myself once having momentary confusion when I was using the accelerator to slow to a stop and suddenly pressed it harder to stop faster. No big deal, quickly fixed, but I think I understand how people drive into mini-marts now when they are distracted. You have to be distracted to do this, because your mind has shifted to the need for a brake press before you foot has shifted to the brake pedal. Still, my preferred solution would be regen to full stop (along with *maybe* automatic hold at stop lights and stop signs), rather than eliminating regen on the accelerator.



Yes, control confusion is almost always found to the the cause of "sudden acceleration" or "unintended acceleration" accidents. Drivers press the accelerator when they think they're pressing the brake. Since pressing it does not slow the car, they press it harder, thus making the situation much worse and potentially fatal to anyone or anything in the path of the vehicle. This is well documented science, and it's also measurable using the "black box" accident data recorder functionality now in cars.

With left foot braking it is much harder to confuse the two controls. The brain becomes accustomed to using one specific foot/leg for braking and the other specific foot/leg for accelerating. To me it feels like different whole sides of the body/brain being engaged. And it connects left and right brain function which is a joy unto itself, whether it's art, dance, music, etc.

I can't recommend left foot braking highly enough. There can be a steep learning curve. It's worth it.


----------



## John

I never actually realized the extent to which to which I used to use my left foot on the brake, but the very first time I drove a Model 3 (You You Xue's) I got the beep warning, and so I've been weaning myself off of it since then. Model 3 really won't let you rest your left foot at all on the brake, so it requires a little retraining for those who occasionally do.


----------



## JeffC

John said:


> I never actually realized the extent to which to which I used to use my left foot on the brake, but the very first time I drove a Model 3 (You You Xue's) I got the beep warning, and so I've been weaning myself off of it since then. Model 3 really won't let you rest your left foot at all on the brake, so it requires a little retraining for those who occasionally do.


There's a dead zone so you can rest your foot on either pedal very lightly without effect, but if you press a bit more, yes, you're operating both pedals (and Teslas will beep at you; a bit paternalistic IMO, but also useful training feedback...)

Typically I rotate either foot away from the pedal when it's truly not needed and rotate the ball of either foot onto its respective pedal and hover over the pedal (and start to touch/feel it), when it's needed. The bottom of the foot rotates on the heel. The top of the foot rotates on the ball of the foot.

You need to find an appropriate place on the floor to rest your heel in order to have the right leverage and angle for each pedal. People do this instinctively and automatically for the accelerator. Learning left foot braking includes learning to do it with the left foot for the brake.

In turns, both feet hover or at least very lightly press the other pedal so they can be engaged/disengaged smoothly and progressively as appropriate.

There's a beautiful left-right symmetry to it, much like a dance with the pedals.

Again, I was able to left foot brake both Model S and Model 3 with no problem after a couple minutes of calibration of feet on pedals. But I've been doing left foot braking for several years now.

(I'm actually a relative newcomer to left foot braking. Almost can't believe how much better it is!)


----------



## Kizzy

My concern with left foot braking is fatigue of both feet/legs. I think I can imagine the switching between brake and accelerator contributing a bit to this, but I really appreciate being able to use cruise control (of any kind) to allow my right foot a chance to rest flat on the floor when on extended trips.


----------



## JeffC

Kizzy said:


> My concern with left foot braking is fatigue of both feet/legs. I think I can imagine the switching between brake and accelerator contributing a bit to this, but I really appreciate being able to use cruise control (of any kind) to allow my right foot a chance to test flat on the floor when on extended trips.


Actually left foot braking distributes more of the work across both legs. So the right leg does a bit less work overall, and the left does a little more. I would say that the right leg is more rested as a result. It feels that way to me too.

Basically driving is much more whole body with left foot braking. The entire body and both left and right sides of the brain are used more, it feels. It's a more holistic driving experience.

For long road trips, one would use cruise control most of the time, and neither leg is doing work most of the time.


----------



## fsKotte

JeffC said:


> 6. A workable solution would be to add a third setting on the Regen control:
> 
> Standard, Low, Regen on Brake


YES. This is exactly what I would want, too.

Then every driving style/preference wins. Another option/addition to your proposal would be to map to one of the steering wheel scroll buttons the functionality of a regen paddle, like the Volt and Bolt have (which was discussed earlier in this thread).

I'm not saying regen on the brake is necessarily better than on the throttle, but I am saying I like (and would appreciate the ability to choose) the feeling of driving with less regen on the throttle, with some/lots of regen on the brake pedal.

And frankly, after a full month of trying One Pedal driving, I find it rather underwhelming in the fun department. I know I'm in the minority on that point, but what am I going to do, pretend to like something that I don't find very compelling? What's the point in that?


----------



## fsKotte

PNWmisty said:


> I will also point out that the title of this thread is incorrect. Because unless you have one foot on the accelerator and one foot on the brake at the same time, the Model 3 does use regen when on the brakes.


In the immortal words of Nigel Tufnel, "Well, that's nitpicking, innit?"

I tried to change the title to "Why do the Model 3 Brakes not activate regen when pressed?" from the original title, but I can't figure out how to edit that.

I guess I see your point, in that when you take your foot off the accelerator pedal, regen is activated, and then you may well press the brakes while the regen is still happening. But that regen, while you're hitting the brakes, is only happening because you lifted your foot off/away from the accelerator pedal; zero of the regen is activated as a result of pressing the brake pedal, and that's sorta what everybody understood the issue to be, based on the thread that ensued after I posted.

But in the end, I think Nigel Tufnel has the right response here . . . .


----------



## fsKotte

Twiglett said:


> Actually maybe I should have put TLC
> Too long don't care


Yes, that would have been more accurate.

But also confusing - why would one be on a thread they don't care about? If I spent my time declaring my apathy about the myriad things/discussions I truly don't care about, I'd be busy 24 hrs a day. . . . .

That said, for anyone who's keeping track, we have exactly one poster who has, in virtual terms, waved their hands up in the air, like They Just Don't Care . . . .


----------



## PNWmisty

fsKotte said:


> I tried to change the title to "Why do the Model 3 Brakes not activate regen when pressed?" from the original title, but I can't figure out how to edit that.


The answer to "*Why don't the brakes activate regen when pressed*?" is *because regen is already activated by the time you press the brake!*

This is a significant reason why it's not only safer but also more efficient. If regen waited until the brake pedal was pressed to activate, then more of the braking duty would fall to the friction brakes, less to regen. You want regen to start early for both safety and efficiency.


----------



## fsKotte

PNWmisty said:


> The answer to "*Why don't the brakes activate regen when pressed*?" is *because regen is already activated by the time you press the brake!*
> 
> This is a significant reason why it's not only safer but also more efficient. If regen waited until the brake pedal was pressed to activate, then more of the braking duty would fall to the friction brakes, less to regen. You want regen to start early for both safety and efficiency.


Where do you get the idea that "more of the braking duty would fall to the friction brakes, less to regen" if regen waited until the brake pedal was pressed to activate? That's not how it works on most of the other brake/regen systems on other EVs.

For instance, in my 500e (which had absolutely no throttle/regen/one-pedal-driving, when you pressed the brake pedal), regen only occurred when you hit the brake pedal, and then ALL of the braking was regen until you got down to around 8mph, where it would switch to mostly friction braking. (except, of course, in an emergency situation, where you had to slam the brakes - then of course the car would engage friction as well as regen right away). On the 500e, you also got to modulate how much regen was applied, depending on how much pressure you put on the brake pedal.

Actually, at this point, I'd change the thread title to, "Why Doesn't Tesla Offer The Option of Putting Regen on the Brake and Not on the throttle?" A lot of people seem to like the one-pedal driving; I don't see the thrill of it frankly. So having an option of putting the regen on the brake, or remapping one of the steering wheel controls to act as a regen paddle (like the V/Bolt) would be something I'd like to see.


----------



## PNWmisty

fsKotte said:


> Where do you get the idea that "more of the braking duty would fall to the friction brakes, less to regen" if regen waited until the brake pedal was pressed to activate? That's entirely wrong and not how it works on most of the other brake/regen systems on other EVs.
> 
> For instance, in my 500e (which had absolutely no throttle/regen/one-pedal-driving, when you pressed the brake pedal), regen only occurred when you hit the brake pedal, and then ALL of the braking was regen until you got down to around 8mph, where it would switch to mostly friction braking. (except, of course, in an emergency situation, where you had to slam the brakes - then of course the car would engage friction as well as regen right away).


It has to do with the timing of the slowing down. With one pedal driving, more duty will naturally fall to regen because of the way the throttle is modulated. You will find yourself controlling your speed early and with more regen vs. if you coast and wait longer to push the brake. I'm sure Tesla has studied this in the real world and determined one pedal driving to be, on average, more efficient.

Those who don't have thousands of miles using one pedal need to try it. It's really a smoother more fluid way to drive in erratic traffic and it's easier on your body because your left foot can remain relaxed on the dead pedal almost all the time (except when needing to come to a complete, zero mph stop).


----------



## fsKotte

PNWmisty said:


> It has to do with the timing of the slowing down. With one pedal driving, more duty will naturally fall to regen because of the way the throttle is modulated. You will find yourself controlling your speed early and with more regen vs. if you coast and wait longer to push the brake. I'm sure Tesla has studied this in the real world and determined one pedal driving to be, on average, more efficient.
> 
> Those who don't have thousands of miles using one pedal need to try it. It's really a smoother more fluid way to drive in erratic traffic and it's easier on your body because your left foot can remain relaxed on the dead pedal almost all the time (except when needing to come to a complete, zero mph stop).


But . . . . when you put the regen on the brake pedal, the friction pads aren't used at all, no matter what (except for emergency braking), until you get to very low speeds. So how would the "timing of the slowing down" affect at all, the amount of friction brakes used? In the 500e system (and others), it doesn't matter when you time the slowing down; it's literally 100% regen until you're down to 8 mph.

And I guess I'll have to put more than the 1,500 miles I've already got on my M3 to appreciate one pedal driving. After 1,500 miles - it's a big bowl of meh. I'm underwhelmed and still prefer it if the regen were on the brake pedal and far less on the throttle. That's my preference.

Also, even if this one-pedal stuff is "more efficient", why not offer an option for brake pedal regen? They already have a "low" regen option that, by definition, is less efficient than "standard", so why not just have a third option for those who like the feel of driving with regen on the brake pedal and not on the throttle?


----------



## GDN

fsKotte said:


> But . . . . when you put the regen on the brake pedal, the friction pads aren't used at all, no matter what (except for emergency braking), until you get to very low speeds. So how would the "timing of the slowing down" affect at all, the amount of friction brakes used? In the 500e system (and others), it doesn't matter when you time the slowing down; it's literally 100% regen until you're down to 8 mph.
> 
> And I guess I'll have to put more than the 1,500 miles I've already got on my M3 to appreciate one pedal driving. After 1,500 miles - meh. Underwhelmed and still prefer it if the regen were on the brake pedal and far less on the throttle. That's my preference.


I'm ignorant on this subject and really stayed out of it just learning what each of you claims is true (damn I could be learning some bad stuff), but I truly have a question about this as you describe it. If I'm at any speed about 8 MPH in your regen with brake situation and I'm in an emergency - a car pulls out in front of me and I slam on the brakes, just how does regen kick in hard enough and fast enough and have enough stopping power, vs some disk brake stopping power? I don't know how regen works, but at a higher speed above 8 MPH and I slam on the brakes, can regen really give me that kind of stopping power?


----------



## PNWmisty

fsKotte said:


> But . . . . when you put the regen on the brake pedal, the friction pads aren't used at all, no matter what (except for emergency braking), until you get to very low speeds. So how would the "timing of the slowing down" affect at all, the amount of friction brakes used? In the 500e system (and others), it doesn't matter when you time the slowing down; it's literally 100% regen until you're down to 8 mph.


That's easy, by braking earlier (as soon as you lift off the throttle all the way) there is less need for friction braking. The early braking starts slowing you down sooner (at a point when you are covering the most ground) which reduces the need to brake harder at the end. Of course, many stops won't need to use the friction brakes regardless of which pedal regen is on, and, in those cases, the efficiency would be the same. It's the cases in which early regen prevents what would have otherwise resulted in friction braking that one pedal driving gets its efficiency advantage.

The safety advantage is more pronounced. In an emergency stop its critical to stop scrubbing speed as soon as possible (because that's when the vehicle is covering the most distance per unit of time). It's a huge advantage for the deceleration to begin occurring_ as soon as_ the driver lifts his/her foot from the accelerator.

But the best reason for one pedal driving is because it's enjoyable as mentioned in the link JeffC provided that contained quotes from the Tesla engineer. People_ enjoy_ the ease and seamlessness of one pedal driving.


----------



## fsKotte

GDN said:


> I'm ignorant on this subject and really stayed out of it just learning what each of you claims is true (damn I could be learning some bad stuff), but I truly have a question about this as you describe it. If I'm at any speed about 8 MPH in your regen with brake situation and I'm in an emergency - a car pulls out in front of me and I slam on the brakes, just how does regen kick in hard enough and fast enough and have enough stopping power, vs some disk brake stopping power? I don't know how regen works, but at a higher speed above 8 MPH and I slam on the brakes, can regen really give me that kind of stopping power?


No, in an emergency situation the pads are engaged instantly, even (and perhaps especially) at higher speeds. At any speed, really, the 500e at least would use the pads when you slammed the brakes in an emergency.


----------



## PNWmisty

GDN said:


> I'm ignorant on this subject and really stayed out of it just learning what each of you claims is true (damn I could be learning some bad stuff), but I truly have a question about this as you describe it. If I'm at any speed about 8 MPH in your regen with brake situation and I'm in an emergency - a car pulls out in front of me and I slam on the brakes, just how does regen kick in hard enough and fast enough and have enough stopping power, vs some disk brake stopping power? I don't know how regen works, but at a higher speed above 8 MPH and I slam on the brakes, can regen really give me that kind of stopping power?


In a panic stop almost all the braking will be provided by friction brakes. The key safety advantage regen on the throttle has is the regen applies some decent braking even before your foot makes it to the brake pedal. At normal city traffic speeds of 25-35 mph, regen is quite strong, strong enough that you are unlikely to need to touch your brakes unless it's a true emergency or you need to come to a complete stop (regen is weak from 5-0 mph.).


----------



## JeffC

The way *regen on brake* works is that, for light braking, 100% is done by regen down to very low speeds. If the pedal is pressed harder, for example, for a stop qucker than regen alone can do, or in an emergency, then the friction brakes are blended in. For a full power stop, all of regen is used, and all of friction braking is used, up to the limit of the tires (really the limit set by ABS, which can be lower). (In some cases regen may not be used in full power stops.)

For typical street driving, regen is always maximized when regenerative braking is integrated with friction brakes on the brake pedal. (Except when the battery is too full / too cold to accept charge from regen, etc. Same as the case for any regen in general.)

(As an aside, this is another way regen on brake is advantageous compared to regen on throttle: when the battery is full or cold and can't accept much charge, thus limiting available regen, if regen is integrated with friction brakes, then the friction brakes do the desired braking, as indicated by how hard the brake pedal is pressed. This results in a more consistent user experience. Want more braking? Press the brake pedal more. How it's delivered, regen vs friction, is largely invisible and irrelevant. The user commands more braking, and ether regen or friction (or both) make it happen, seamlessly, consistently, and without any confusion about which pedal is responsible for providing it: it's the brake pedal.)

For some numbers, a typical car can do about a Megawatt of friction braking (for a short period of time). Regen on EVs can do around 50 kW. So about 20x more braking power is available from the friction brakes.

The trick when using *regen on throttle* (one pedal driving), is to learn to lift off the throttle smoothly and slowly. Basically it requires a bit more sensitivity in the operation of the controls.

As with learning left foot braking, there is some learning curve. The learning curve for one pedal driving is arguably shorter since folks are already accustomed to engine braking (compression braking) from throttle lift on internal combustion cars.


----------



## PNWmisty

fsKotte said:


> No, in an emergency situation the pads are engaged instantly, even (and perhaps especially) at higher speeds.


The friction brakes will come on at the same time they would in a traditional car (but it's not instant).


----------



## GDN

fsKotte said:


> No, in an emergency situation the pads are engaged instantly, even (and perhaps especially) at higher speeds. At any speed, really, the 500e at least would use the pads when you slammed the brakes in an emergency.


Thanks - at least that helps clarify what I've been trying to understand how the engine could handle that kind of braking.


----------



## fsKotte

PNWmisty said:


> That's easy, by braking earlier (as soon as you lift off the throttle all the way) there is less need for friction braking. The early braking starts slowing you down sooner (at a point when you are covering the most ground) which reduces the need to brake harder at the end. Of course, many stops won't need to use the friction brakes regardless of which pedal regen is on, and, in those cases, the efficiency would be the same. It's the cases in which early regen prevents what would have otherwise resulted in friction braking that one pedal driving gets its efficiency advantage.
> 
> The safety advantage is more pronounced. In an emergency stop its critical to stop scrubbing speed as soon as possible (because that's when the vehicle is covering the most distance per unit of time). It's a huge advantage for the deceleration to begin occurring_ as soon as_ the driver lifts his/her foot from the accelerator.
> 
> But the best reason for one pedal driving is because it's enjoyable as mentioned in the link JeffC provided that contained quotes from the Tesla engineer. People_ enjoy_ the ease and seamlessness of one pedal driving.


Your explanation is unconvincing. Why, if you're using 100% regen anyway, from the moment you touch the brake pedal all the way down to 8 mph in my 500e (and note also that the Tesla switches to friction braking also at a similar low speed, even in "standard" regen mode), are you somehow using friction braking more? It doesn't matter what speed you're starting the deceleration, if it's 100% regen down to around 8 mph. You *only use your friction brakes* when you are at this low speed threshold.

In my 500e, no matter what my speed, there was never *any* friction braking, *at all*, until 8 mph. Unless you slammed on the brakes, of course.

If your best reason for one pedal driving is because it's enjoyable, well then we can at least settle on that point by noting that I do not find it appreciably more enjoyable. After 1.5 thousand miles trying it, I'm fully underwhelmed. I wish they had an option for brake regen / no throttle regen, for the way I find EV driving to be most enjoyable.


----------



## PNWmisty

fsKotte said:


> Why, if you're using 100% regen anyway, from the moment you touch the brake pedal all the way down to 8 mph in my 500e (and note also that the Tesla switches to friction braking also at a similar low speed, even in "standard" regen mode), are you somehow using friction braking more? It doesn't matter what speed you're starting the deceleration, if it's 100% regen down to around 8 mph. You *only use your friction brakes* when you are at this low speed threshold.


Two reasons:
1) Regen is more efficient at higher motor speeds. A longer, slower deceleration will charge the batteries more than a quick deceleration (even if the deceleration is 100$ regen/0% friction).
2) Regen coupled with the accelerator will reduce the situations in which it_ is_ necessary to apply friction brakes.

The RWD Model 3 can only regen brake using the rear wheels and the amount it can regen is traction limited in many situations. The one pedal driving maximizes the amount of regen by engaging sooner with typical drivers. You could argue someone in a car setup up with regen coupled to the brake could match the efficiency of regen on the accelerator by skillfully using left foot braking, and you would be correct. But in the real world, most drivers would not manage that. And that is because one of the biggest problems with left foot braking is the inadvertent application of throttle and brake simultaneously. This is even a problem for Formula 1 drivers and I can show you footage of crashes likely caused by driver fatigue near the end of the race and a failure to operate the throttle correctly with their right foot while their left foot was applying the brake. And on the street, you will sometimes see left foot brakers riding the brake with their left foot. You can tell them apart because the brake lights are on, even as they accelerate or maintain a constant speed. This is bad for efficiency and bad for brake life. Many don't even know they are riding their brakes.



> If your best reason for one pedal driving is because it's enjoyable, well then we can at least settle on that point by noting that I do not find it appreciably more enjoyable. After 1.5 thousand miles trying it, I'm fully underwhelmed.


Yep, that's normal, everyone is different. That's why the quote from the engineer in JeffC's link was that "_almost _everyone" finds it enjoyable. He fully admits there are a few people who want it to just coast. But I am solidly in that "almost everyone" majority, the market that Tesla is targeting. It would be a real pity if they started catering to the minority and were a colossal failure because of that.


----------



## PNWmisty

fsKotte said:


> If your best reason for one pedal driving is because it's enjoyable, ...


I might have taken a little pleasurable liberty with that claim. The_ best_ reason for one pedal driving is it's safer. By causing full regen as soon as the accelerator is fully released.


----------



## GDN

JeffC said:


> The trick when using *regen on throttle* (one pedal driving), is to learn to lift off the throttle smoothly and slowly. Basically it requires a bit more sensitivity in the operation of the controls.


Although I was having a bit of fun learning to drive on the higher regen, this is likely why I've already switched to the lower regen setting - I'm not a very "Sensitve" guy and didn't operate it well. I may have to switch it back on just to say I've conquered it, but the 3 is also not my primary vehicle to drive, so it does take adjusting going back and forth. If it was my primary driver then I would embrace it more than I've tried so far.


----------



## JeffC

PNWmisty said:


> In a panic stop almost all the braking will be provided by friction brakes. The key safety advantage regen on the throttle has is the regen applies some decent braking even before your foot makes it to the brake pedal. At normal city traffic speeds of 25-35 mph, regen is quite strong, strong enough that you are unlikely to need to touch your brakes unless it's a true emergency or you need to come to a complete stop (regen is weak from 5-0 mph.).


I understand your point about regen on throttle enabllng quicker (initial) braking, and agree.

However the ergonomic downside is that it creates confusion about which pedal is providing braking. With regen on throttle, both pedals provide braking, but the driver must change modes to engage the friction brakes. Unless they use left foot braking, there is some delay caused by that transition also. That too is a potential safety issue since it objectively adds to total reaction time. And it adds reaction time in the most detrimental cases: an emergency where friction brakes are actually needed.

(To be fair, that's a detriment caused by one foot driving far more than regen on throttle: transition time of moving the right foot from one pedal to the other. Left foot braking can be more efficient at operating both controls, when needed. I actually hover my left foot over the brake at busy intersections, pedestrians by the side of the road, etc. in order to be able to brake quickly if needed. If there's any potential for needing to brake, I'm prepared to brake quickly with my left foot by pre-positioning it over the brake pedal. That's much harder to do with only the right foot, though possible.)


----------



## fsKotte

PNWmisty said: 
"Two reasons:
1) Regen is more efficient at higher motor speeds. A longer, slower deceleration will charge the batteries more than a quick deceleration (even if the deceleration is 100$ regen/0% friction).
2) Regen coupled with the accelerator will reduce the situations in which it_ is_ necessary to apply friction brakes."

Two problems:
1) What's "more efficient" has nothing to do with whether friction braking is used via the brake pedal when regen is put on that pedal (instead of the throttle), so an efficiency argument does not answer the question. I'll grant you, for the sake of argument, that "one pedal" driving is more efficient. But that efficiency has zero to do with the idea that you're using the friction braking more when regen is on the brake and not on the throttle.
2) No, wrong. Regen coupled with the brake will apply the same level of regen that you would if it were on the throttle. Again: Friction brakes only come on when the speed is very low, or if the regen resistance isn't sufficient to stop the vehicle. At the beginning of the deceleration, it's still 100% regen, even when it's all on the brake pedal.

PNWmisty said: 
"It would be a real pity if they started catering to the minority and were a colossal failure because of it."
They already cater to the "minority" by having a Low regen option. They already cater to a "minority" by having three steering sensitivity settings - should they eliminate all but the one that only the Majority prefers? What about temperature/climate control - should they only provide the temperature options that the "majority" prefers? That would be the real pity actually . . . .

But, really - any time you provide more than one option for something, you're "catering" to some minority, somewhere. I don't see how having a brake regen option would be any different than having a third steering option. Why not have it? I'm not advocating for changing the one-pedal option in any way shape or form - you'd get to keep that, and all the pleasure you derive from it. I'm only advocating for adding another choice.

Have we slipped into a DEVO situation, where "Freedom From Choice" is preferable to "Freedom of Choice"? (That's an obscure reference, but, well, that's all)


----------



## fsKotte

PNWmisty said:


> I might have taken a little pleasurable liberty with that claim. The_ best_ reason for one pedal driving is it's safer. By causing full regen as soon as the accelerator is fully released.


That's fine - it's safer, it's more efficient. I'll go with that.

But note that they haven't designed the options in the M3 to only be the safest, to only provide the most efficient. For instance, they have a less safe option already, a less efficient option already, called "Low" regen (where you don't return as much kw back to the batteries, and you have to move your foot over to brake more, than with "standard").

Let's just add a third option (steering has three options), for brake pedal regen. In fact, brake pedal regen would at least be more efficient than "low" regen, since you'd still use more regen with brake pedal activation than with "low" regen on the throttle setting, which simply and literally lowers the amount of regeneration applied when you let off the throttle.


----------



## garsh

Since we no longer have a clutch pedal, we should instead have a "regen" pedal and a "brake" pedal in addition to the "go" pedal.


----------



## fsKotte

garsh said:


> Since we no longer have a clutch pedal, we should instead have a "regen" pedal and a "brake" pedal in addition to the "go" pedal.


Just add an option next to "low" and "Standard", called "Brake Regen" that moves the regen to the brake pedal. Problem solved.


----------



## PNWmisty

fsKotte said:


> They already cater to the "minority" by having a Low regen option.


True, I love the way Tesla gives us lots of options to tailor the driving experience to how each individual prefers. In this case, it adds minimal cost and complexity because it's a simple software change.



> I don't see how having a brake regen option would be any different than having a third steering option. Why not have it? I'm not advocating for changing the one-pedal option in any way shape or form. I'm only advocating for adding another choice.


I'm all for offering it as a choice and it's a choice I would actually use on empty country roads even though I prefer regen on the accelerator in traffic and on any Interstate due to the safety factor over regular ICE cars and the seamless way that regen integrates with other traffic. Because traffic can be erratic and regen on brake is magic in those situations. I wouldn't give it up. Having both options is possible and desirable although it would add to the cost of the vehicle due to a more complex brake pedal hardware interface and, due to the critical nature of braking to vehicle safety, it would require a lot more development, testing and certification expenses in addition to more expensive hardware and assembly. It would also add development time. But I would pay more for that (even though many wouldn't). Tesla would like to give us that option too but they made a cost-benefit decision and stuck to it. They can't give us every possible feature and stick to their price goals. They already gave us too much which is why the $35,000 base model is not yet available. This car is far nicer than I imagined it would be when we ordered it.

I'll advocate for another choice too as long as it doesn't cause the car to fail due to high costs or delay the production ramp. But don't take away the regen on the accelerator because that's a good portion of what makes the Model 3 so damn fun to drive!


----------



## PNWmisty

garsh said:


> Since we no longer have a clutch pedal, we should instead have a "regen" pedal and a "brake" pedal in addition to the "go" pedal.


That would be REALLY cool! Seriously!

But I would still want the one pedal driving option!


----------



## fsKotte

PNWmisty said:


> Having both options is possible and desirable although it would add to the cost of the vehicle due to a more complex brake pedal hardware interface and, due to the critical nature of braking to vehicle safety, it would require a lot more development, testing and certification expenses in addition to more expensive hardware and assembly. It would also add development time. But I would pay more for that (even though many wouldn't). Tesla would like to give us that option too but they made a cost-benefit decision and stuck to it. They can't give us every possible feature and stick to their price goals. They already gave us too much which is why the $35,000 base model is not yet available. This car is far nicer than I imagined it would be when we ordered it.
> 
> I'll advocate for another choice too as long as it doesn't cause the car to fail due to high costs or delay the production ramp. But don't take away the regen on the accelerator because that's a good portion of what makes the Model 3 so damn fun to drive!


Don't worry, nobody's looking to take away your throttle regen nirvana.

But I'm not at all convinced that it's much more expensive to provide regen on the brake pedal, and that such expense would be why we don't have it on the M3.

You've speculated on the cost, but it's just that - speculation. Note also that even when expense is less or no object, Tesla still does not offer regen on the brake pedal. Specifically, the S and X are pricey vehicles, with no expense spared on them, and yet they do not have a Brake Regen option.

Note also that brake pedal regen is standard on many of the lower-end EV's (Fiat 500e, Leaf, etc). So I'm just not convinced that it would be a herculean and/or prohibitively expensive option to implement. It may not be amenable to an OTA update, and since I have my car already I wouldn't get the advantage of it, if it did require some amount of hardware change. But it's still a good idea, to have it, and it may very well not be that expensive at all to add.

And really now, come on: I do not think advocating for the option of Regen on the brake pedal would cause the car to "fail" in any manner, at all.

And again, just to reassure you - nobody is wanting to take away your beloved one-pedal driving feature.


----------



## PNWmisty

fsKotte said:


> But I'm not at all convinced that it's much more expensive to provide regen on the brake pedal, and that such expense would be why we don't have it on the M3.


I don't claim to know HOW MUCH it would cost but there is no doubt it would increase costs and take time to develop, test and certify. That's a given.



> Note also that brake pedal regen is standard on the cheapest of cheap EV's (Fiat 500e, Leaf, etc). So I'm just not convinced that it would be a herculean and/or prohibitively expensive option to implement.


But they don't have regen on the accelerator! It's offering both that I'm saying would cost more. Also, there isn't a single EV ever made that had seamless and non-mushy feeling regen on the brake pedal. I'm going by reviews of others who have driven the rest. On the other hand, all reviewers say the Model 3 has very good to excellent brake feel, firm and progressive. Soft, mushy or non-proportional brakes are a deal killer for me. I want a good brake feel when I need them.



> And really now, come on: I do not think advocating for the option of Regen on the brake pedal would cause the car to "fail" in any manner, at all.


Of course not, but that's not what I said (that advocating for either option would cause the Model 3 to fail). I said additional cost MAY. It's a fine line.



> And again, just to reassure you - nobody is wanting to take away your beloved one-pedal driving feature.


As the Tesla development engineer was quoted "Almost everyone" likes regen on the accelerator. And that's why it shouldn't be taken away. It's not about what_ I_ want. And that is how this whole discussion was reborn, by JohnC making the unsupported claim that Tesla chose the wrong pedal to couple regen with. All electric cars with regen on brake have failed (or are in the process of failing). I understand the development cost of the Bolt was around $2 billion dollars or more. And yet the Model 3 is already outselling it and the Bolt numbers just get worse each month. If you want regen on the brake, just buy a Bolt! And do it before its not offered anymore. Because it's failing!


----------



## Dr. J

fsKotte said:


> Why Doesn't Tesla Offer The Option of Putting Regen on the Brake and Not on the throttle?"


Because it would be expensive to implement. They kept the braking system simple by putting regen on the accelerator.

Also, I read (somewhere, can't remember now) that the reason the Model 3 doesn't regen all the way to 0 MPH is because below a certain speed, it "costs" more power than it "saves." So the implementation we see is the most efficient, given those constraints. Thus,


----------



## fsKotte

PNWmisty said:


> I don't claim to know HOW MUCH it would cost but there is no doubt it would increase costs and take time to develop, test and certify. That's a given.
> 
> But they don't have regen on the accelerator! It's offering both that I'm saying would cost more. Also, there isn't a single EV ever made that had seamless and non-mushy feeling regen on the brake pedal. I'm going by reviews of others who have driven the rest. On the other hand, all reviewers say the Model 3 has very good to excellent brake feel, firm and progressive. Soft, mushy or non-proportional brakes are a deal killer for me. I want a good brake feel when I need them.
> 
> Of course not, but that's not what I said (that advocating for either option would cause the Model 3 to fail). I said additional cost MAY. It's a fine line.
> 
> As the Tesla development engineer was quoted "Almost everyone" likes regen on the accelerator. And that's why it shouldn't be taken away. It's not about what_ I_ want. And that is how this whole discussion was reborn, by JohnC making the unsupported claim that Tesla chose the wrong pedal to couple regen with. All electric cars with regen on brake have failed (or are in the process of failing). I understand the development cost of the Bolt was around $2 billion dollars or more. And yet the Model 3 is already outselling it and the Bolt numbers just get worse each month. If you want regen on the brake, just buy a Bolt! And do it before its not offered anymore. Because it's failing!


Sadly, you offer no real facts that the cost would be prohibitive, unless you're implying that the Bolt folks spent $2 Billion on brake regen. Also, is the Bolt failing because it has a Regen on Brake option? That's a stretch, let's be honest. And for the real stretch, we have your clear implication that all EV's with regen on brake are failing *because* they have regen on the brake. Really? I mean, Really?

And lastly, is it so awesome if the Bolt fails? Are Tesla's the only EV's that will not fail, and are they not failing because of that awesome regen on the throttle? Let's hope not. There's plenty of room here, to grow, and Elon's own position is, the more competition/options the better, because more EV's are better.

I have an M3, and love it. Everybody has things about the cars they like/love, that they'd like to see improved/adjusted. For me, it's Brake on Regen. For you, that would be a catastrophe, apparently, of cost and needless pandering to a "minority".


----------



## fsKotte

Dr. J said:


> Because it would be expensive to implement. They kept the braking system simple by putting regen on the accelerator.
> 
> Also, I read (somewhere, can't remember now) that the reason the Model 3 doesn't regen all the way to 0 MPH is because below a certain speed, it "costs" more power than it "saves." So the implementation we see is the most efficient, given those constraints. Thus,


How expensive? Do you have figures? You're just speculating, which is fine. But let's just be clear on that.

Most EV's don't regen at the lower speeds - regardless of where they put that regen (throttle or brake). Not just Teslas.


----------



## Dr. J

fsKotte said:


> You're just speculating, which is fine. But let's just be clear on that.


Yes. Yes, I am. What would this forum be without widespread rampant speculation?


----------



## fsKotte

Dr. J said:


> Yes. Yes, I am. What would this forum be without widespread rampant speculation?


Agree! Speculation is the foundation upon which almost all online forums are based!


----------



## JeffC

The cost of adding regen on brake would mostly be the engineering development work, which is substantial (possibly several millions of dollars, as it's hard to do well), and related software and documentation changes. However the bulk of the engineering work would only need to be done once, then could be applied to all Tesla vehicles by using different calibrations specific to those models. (Tesla, being a multi-billion dollar and growing company, could probably afford it, easily.)

It is absolutely doable.

Note that basically all other EV and hybrid manufacturers do put regen on brake. (They do spend the money to do that integration properly.) Some also add regen on throttle options.


----------



## PNWmisty

fsKotte said:


> Sadly, you offer no real facts that the cost would be prohibitive,...


I never said the cost would be prohibitive. Only Tesla knows. I just said it would cost more and that cars are somewhat price sensitive.



> And lastly, is it so awesome if the Bolt fails?


I didn't say or imply that. I said the Bolt has regen on the brake pedal and it's failing. It also offers inferior brake feedback compared to the Model 3. The market offers choices, Tesla made theirs and, if you don't like it you can go to the competition (which, currently is the Bolt). All I'm saying is that I think Tesla made the right decision here and myself and the vast majority prefer the feeling of one pedal driving.

Or you can modify your Model 3 to get regen on the brake pedal if it's so important to YOU.

If you are going to respond to me I would really appreciate it if you didn't mischaracterize my words. I think I state my positions very clearly, without a lot of room for ambiguity. It doesn't help your cause to pretend I've said things I haven't.


----------



## PNWmisty

JeffC said:


> Note that basically all other EV and hybrid manufacturers do put regen on brake. (They do spend the money to do that integration properly.) Some also add regen on throttle options.


I would like to know which EV offers the choice of regen on the throttle or the brake pedal.

Because I'm not aware of any.


----------



## JeffC

PNWmisty said:


> I would like to know which EV offers the choice of regen on the throttle or the brake pedal.
> 
> Because I'm not aware of any.


VW e-Golf, Chevy Volt 2, previous Leaf all at least have some off-throttle regen simulating combustion engine braking drag (roughly equivalent to low regen setting on Tesla Model S, etc.). Some have variable levels of regen on throttle, for example using steering wheel paddles on VW. And all do also put regen on the brake. These are a few examples. There are probably others.

For example, at the highest levels e-Golf has much stronger off-throttle regen than Tesla. It's like a "downhill gear" mode on an ICE to slow your descent on a steep downhill using motor regen like ICE compression braking. (Toyota RAV4 EV built by Toyota not Tesla also has this, as did EV1 if I remember correctly.)

In addition, VW also fully integrates regen on the brake pedal.


----------



## garsh

PNWmisty said:


> I would like to know which EV offers the choice of regen on the throttle or the brake pedal.


It's not a "choice" as in something you can configure one way or the other. They just do both. The Leaf has some off-throttle regen, AND it adds more regen when you hit the brake pedal.


----------



## Dr. J

garsh said:


> It's not a "choice" as in something you can configure one way or the other. They just do both. The Leaf has some off-throttle regen, AND it adds more regen when you hit the brake pedal.


I realize the Prius is a toy compared to these true EVs, but anyone know how its regen differs? Seems like it's regenning nearly constantly while coasting and braking.


----------



## fsKotte

PNWmisty said:


> I never said the cost would be prohibitive. Only Tesla knows. I just said it would cost more and that cars are somewhat price sensitive.
> 
> I didn't say or imply that. I said the Bolt has regen on the brake pedal and it's failing. It also offers inferior brake feedback compared to the Model 3. The market offers choices, Tesla made theirs and, if you don't like it you can go to the competition (which, currently is the Bolt). All I'm saying is that I think Tesla made the right decision here and myself and the vast majority prefer the feeling of one pedal driving.
> 
> Or you can modify your Model 3 to get regen on the brake pedal if it's so important to YOU.
> 
> If you are going to respond to me I would really appreciate it if you didn't mischaracterize my words. I think I state my positions very clearly, without a lot of room for ambiguity. It doesn't help your cause to pretend I've said things I haven't.


I'm sorry that you believe I've mischaracterized your words. That's not my intention.

In terms of the Bolt, just to be clear, so that I don't mischaracterize your words, you've stated that "the Bolt has regen on the brake pedal and it's failing." It might be reasonable to take from that statement an implication - an imputation - that what you mean is that it's failing *because* it has regen on the brake pedal, but I will be careful here not to attribute that causation to your words. You probably did not mean, at all, did you, that the Bolt is failing *because* it has regen on the brake pedal. And so I won't attribute that meaning to your words then.

Suffice it to say, there are many reasons a car might fail. Looks/design, for instance (Fancy yourself a Bolt design fan??? Didn't think so). Or inferior materials (Have you been in a Bolt? It's got pretty flimsy, cheap-feeling/looking material throughout). Or less performance (Bolt is slower than the M3 0-60, but it's not super slow. But still, it's no M3). Or charging network (or lack thereof, with the Bolt, compared to the Superchargers).

Another very specific example of why the Bolt lost at least one customer: When I was casting about for what to do if my Model 3 invite did not come in a timely fashion, I considered the Bolt. My wife flat-out prohibited it specifically because it's so damned ugly, and it was hard for me to dispute that. How many sales of the Bolt have been lost due solely to it's overwhelmingly plebeian looks? I'm gonna speculate here, and say: Lots. Lots and lots of people aren't buying the Bolt because first and foremost, they don't want to be seen in it.

One thing's for sure, my wife did not say to me, "Don't get that Bolt. It has regen on the Brake pedal; screw that."

Your statement to the effect that if I "don't like" my M3 then "you can go to the competition (which, currently is the Bolt)" falls flat. It sounds a little like, "America: Love it or Leave it". Which statement is sort of missing the whole idea, in the sense that if you love it, and you see a way to improve it, you should say something, even if it's critical of that thing. I love many many things about my M3, but I'd like it even more if there was an option to either place the regen on the brake or have a paddle-like option mapped to the steering wheel controls.

Put another way: Tesla prides itself on customer feedback, and they take a number of suggestions from owners and sometimes they actually implement those suggestions. Wouldn't it be a better epithet to throw my way, to tell me that if I "don't like it" then I should submit an email to Tesla to let them know, to suggest adding this option (which I've done, BTW)? Seems that would be more in the spirit of Tesla, rather than admonishing me to somehow "modify" my own M3 (which is flat-out ridiculous, and of course you know that), or to go buy a Bolt instead (also prima facie absurd).


----------



## Technical48

Dr. J said:


> I realize the Prius is a toy compared to these true EVs, but anyone know how its regen differs? Seems like it's regenning nearly constantly while coasting and braking.


The 2nd gen Prius regenerates a little while coasting, and depressing the brake adds regen depending on the linear position of the brake pedal. Depressing the pedal further will eventually engage friction braking. (Interestingly, the force exerted by the brake pedal back to the braking foot/leg is completely artificial except when certain failure modes will result in the brake pedal hydraulically actuating the rear brakes). Below about 8 mph, regen is inhibited and friction braking takes over.

The Prius brakes...oddly. I never liked it. I much prefer the Tesla philosophy of completely separating regen from friction braking. The simplicity alone is enough to prefer this. The Prius braking system is ridiculously complex and prone to odd behavior, as covered by others earlier in this thread.


----------



## Dr. J

Technical48 said:


> The 2nd gen Prius regenerates a little while coasting, and depressing the brake adds regen depending on the linear position of the brake pedal. Depressing the pedal further will eventually engage friction braking. (Interestingly, the force exerted by the brake pedal back to the braking foot/leg is completely artificial except when certain failure modes will result in the brake pedal hydraulically actuating the rear brakes). Below about 8 mph, regen is inhibited and friction braking takes over.
> 
> The Prius brakes...oddly. I never liked it. I much prefer the Tesla philosophy of completely separating regen from friction braking. The simplicity alone is enough to prefer this. The Prius braking system is ridiculously complex and prone to odd behavior, as covered by others earlier in this thread.


Cool! Thanks. I'll review the thread, see what I missed.


----------



## John

Technical48 said:


> The Prius brakes...oddly. I never liked it.


Yeah, I've had three Priuses and I always thought the anti-slip software was janky. Every time you rattled the wheels on a bump, the anti-lock would pulse. On my first one, the first stop or two after leaving the house in the morning would pulse.
,


----------



## Technical48

fsKotte said:


> I'm gonna speculate here, and say: Lots. Lots and lots of people aren't buying the Bolt because first and foremost, they don't want to be seen in it.


LOL! So true.


----------



## Dr. J

John said:


> Yeah, I've had three Priuses and I always thought the anti-slip software was janky. Every time you rattled the wheels on a bump, the anti-lock would pulse. On my first one, the first stop or two after leaving the house in the morning would pulse.
> ,


I've got a 2006 Prius (130,000 miles) and besides this issue, there's also the issue of starting on ice from a dead stop--the car just freezes. Apparently it's the traction control. Very dangerous.


----------



## JeffC

Regenerative braking on the first generation Prius was not well integrated with the friction braking. On later generations of Prius, it was significantly improved. On the EV1 it was nearly seamless, as it is on our RAV4 EV made by Toyota and not Tesla. e-Golf, Leaf, Volt and many other EVs and hybrids have very well integrated regen and friction braking.


----------



## JeffC

Technical48 said:


> The Prius brakes...oddly. I never liked it. I much prefer the Tesla philosophy of completely separating regen from friction braking. The simplicity alone is enough to prefer this. The Prius braking system is ridiculously complex and prone to odd behavior, as covered by others earlier in this thread.


When done well, regen integrated with friction braking is seamless. One presses the brake pedal and at first gets regen. As the car comes to a stop, or harder braking is commanded by the driver (or ABS, etc.), friction braking is progressively blended in. When it's done well, the blending is seamless and imperceptible.

It can be done less than well. It takes significant engineering effort to do it well. It may be harder to do well than ABS calibration, which is quite complex and needs to take into account many widely varying road conditions, etc.


----------



## PNWmisty

JeffC said:


> VW e-Golf, Chevy Volt 2, previous Leaf all at least have some off-throttle regen simulating combustion engine braking drag (roughly equivalent to low regen setting on Tesla Model S, etc.). Some have variable levels of regen on throttle, for example using steering wheel paddles on VW. And all do also put regen on the brake. These are a few examples. There are probably others.
> 
> For example, at the highest levels e-Golf has much stronger off-throttle regen than Tesla. It's like a "downhill gear" mode on an ICE to slow your descent on a steep downhill using motor regen like ICE compression braking. (Toyota RAV4 EV built by Toyota not Tesla also has this, as did EV1 if I remember correctly.)
> 
> In addition, VW also fully integrates regen on the brake pedal.


Which of those offer one pedal driving? Because you said some offer the option to put regen on the throttle or the brake. And if it doesn't allow me to put all the regen on the throttle then I'm not sure that would qualify as "one pedal driving" which is what I hear most people relating favorably after trying the Model 3.

And I'm not interested in hybrids. The last thing I need is an electric car that also has gas tank, fuel pump, engine oil, fuel injectors, starter motor, spark plugs, catalytic converter, muffler, exhaust pipe and header, air filter, etc, etc, etc. Electric cars are better when they are pure electric. Much better.


----------



## JeffC

PNWmisty said:


> Which of those offer one pedal driving? Because you said some offer the option to put regen on the throttle or the brake. And if it doesn't allow me to put all the regen on the throttle then I'm not sure that would qualify as "one pedal driving" which is what I hear most people relating favorably after trying the Model 3.
> 
> And I'm not interested in hybrids. The last thing I need is an electric car that also has gas tank, fuel pump, engine oil, fuel injectors, starter motor, spark plugs, catalytic converter, muffler, exhaust pipe and header, air filter, etc, etc, etc. Electric cars are better when they are pure electric. Much better.


They all have regen on throttle, and regen on brake. VW has variable regen on throttle, controlled by the steering wheel paddles. (On ICE VWs the paddles are used to change gears.)

Via paddle adjustments, the e-Golf regen on throttle ranges from very light (much lighter than Low on Teslas; almost coastng) to very high (much higher than Standard on Teslas; strong enough to go slowly down a steep hill with no throttle or brake applied). And it has multiple levels of regen in between. (It's very cool, but also potentially somewhat confusing.) At the medium high regen on throttle levels, e-Golf definitely has one pedal driving.

e-Golf also has regen on brake. When you step on the brake pedal, all of the initial low power braking is done by regen. (Same as Leaf, Volt, etc.) If you step harder on the brake pedal, or to reach a complete stop, you get into friction braking.

Totally agree EVs are better than hybrids, the main reason of which is the great simplification. Hybrids add the complexity of both ICE and EV drivetrains; roughly double the complexity and twice as much to go wrong. Also all the same maintenance as ICE, oil changes, oil leaks, lots of waste heat and big cooling systems, etc.

Two main benefits of hybrids: 1. They are more efficient ICE. If people must have ICE during a transition to EVs, at least they're more efficient. 2. They teach people about EV mode. Specifically plug in hybrids can show people than a longer-range, pure EV can likely meet all of their daily driving needs. If EV mode in a hybrid can meet most or all of it, that helps to prove the case for pure EVs for people afraid of range anxiety (and unaware of how little they actually drive each day).

It's important to keep an open mind and consider all sides.


----------



## fsKotte

PNWmisty said:


> Electric cars are better when they are pure electric. Much better.


Bingo. Common ground found. I agree with you here.


----------



## John

Thought about this thread a little as I was driving around today.
Definitely glad the car has regen on the accelerator pedal. 
Extremely graceful and ergonomic to stay on one pedal most of the time.
I end up wishing the other pedal could be used even less.


----------



## garsh

As long as everybody remains civil (and thanks everybody for keeping it so ), I'm happy to leave this thread open.

But honestly.... I think just about every point on every side has been made at least three times over.


----------



## Bernard

fsKotte said:


> I just learned that my M3 (as I believe all Teslas) does not use any regen when I apply the brake pedal.
> 
> This surprised me, as I've had previous EV's that do use some regen when you hit the brake pedal, and I found it to be pretty efficient in utilizing the battery (coast and use no/less energy when you could, and then always use regen when you needed to scrub some speed, via "brake" pedal).
> 
> Anybody know why Tesla has chosen to not use any additional regen when you hit the brake pedal? This is interesting to me because I always thought the most efficient way to drive an EV would be to have the ability to coast when you can, and then regain some energy via regen when you need to slow down. I get that "One Pedal" driving can be fun, but I don't get how it's more efficient, when the regen is always on, and so you're never coasting, always applying energy/electricity to keep the car moving . . . .
> 
> I'm sure I'm missing something here, so appreciate any enlightenment. . . .


Very simple: 99% of the time, you do *not* use the brakes to brake the car -- you just lift the accelerator pedal some or a lot (which means regen). I never touch the brake pedal in normal driving, except when parking, holding on a hill, or at a traffic stop when I am not in adaptive cruise control or when there is no car ahead of me (and, of course, in real emergency braking, but we all hope that's real uncommon). With practice you'll find you can race up a mountain road without using the brakes for hairpins or any curves -- regen is very strong on level roads or climbing roads. (You may need brake assist to regen when going fast down the same mountain road, however, as regen does not quickly slow down your Model 3 running down the hill at 60mph; but you do not need any braking downhill to maintain any chosen speed that allows you to take the curves ;-)
Once you drive that way, the regen gain when using the brakes would be tiny and the engineering to enable it another complication for Tesla, so why bother?
(And if you are determined to beat the Pikes Peak record, which will require you to decelerate as fast as you accelerate, something regen cannot do, then you are no longer into efficiency territory anyway ;-)

At heart, I think the issue is that you misunderstand what regen in the Tesla does: coasting is automatically "included", in that, whenever the speed you demand via the accelerator is no higher than the speed of the car just coasting down the hill, or when you are "coasting to a stop" (which you do by slowly letting the accelerator pedal up), the car recovers energy. It probably does that far more efficiently than we could ourselves by having some sort of explicit coasting mode -- at least I have been very impressed by its regen capabilities.


----------



## garsh

Bernard said:


> It probably does that far more efficiently than we could ourselves by having some sort of explicit coasting mode


Coasting is always going to be more efficient than regen. Having to hold the accelerator at the "correct point" to get coasting is a PITA - I can see the appeal in having an explicit coasting mode to rest the right leg.


----------



## Bernard

fsKotte said:


> I just learned that my M3 (as I believe all Teslas) does not use any regen when I apply the brake pedal.
> 
> This surprised me, as I've had previous EV's that do use some regen when you hit the brake pedal, and I found it to be pretty efficient in utilizing the battery (coast and use no/less energy when you could, and then always use regen when you needed to scrub some speed, via "brake" pedal).
> 
> Anybody know why Tesla has chosen to not use any additional regen when you hit the brake pedal? This is interesting to me because I always thought the most efficient way to drive an EV would be to have the ability to coast when you can, and then regain some energy via regen when you need to slow down. I get that "One Pedal" driving can be fun, but I don't get how it's more efficient, when the regen is always on, and so you're never coasting, always applying energy/electricity to keep the car moving . . . .
> 
> I'm sure I'm missing something here, so appreciate any enlightenment. . . .


If you've driven stick-shift cars with clutch, you know that you anticipate slowdowns and stops by downshifting, more than once if needed, before starting to use the brakes. In that same vein, think of the Tesla as a car that has a huge number of "gears" and constantly "shifts" up and down to maintain optimal performance -- and whenever the "downshift" is made in order to slow down the car, it really means regen.
I never liked automatic transmissions, not even those with optional up-and-down shifters, as they could never offer the fine touch of the gerar+clutch, and feared that EV driving might resemble a bad automatic transmission. But it's quite the opposite with a Tesla: the regen is great and almost always just what you need (and of course the acceleration is almost independent of slope, load, and current speed, the variables that forced you to change gear in an ICE car).



garsh said:


> Coasting is always going to be more efficient than regen. Having to hold the accelerator at the "correct point" to get coasting is a PITA - I can see the appeal in having an explicit coasting mode to rest the right leg.


I don't see how. At the end of coasting, you'll have to brake, often harder than regen can provide and so use the actual brakes, thus wasting energy; and trying to guess when to stop coasting by getting into regen so at to avoid having to use the brakes is not something you can do that well. The regen system is always going to be more efficient than some kind of coasting. Not to mention that you would also need some kind of switch to distinguish between "off the accelerator => coast" and "off the accelerator => regen". I would not want to modulate power with a combination of a hand or foot switch and the accelerator... (You could not set it so that off-accelerator would pure coasting and slowing down would require the brake pedal, because you would then need something to distinguish emergency breaking from regen braking, and I'd think that would be a source of potentially lethal mistakes...)

As to keeping the right foot on the accelerator, it's the simplest way to keep control of the car speed, better by far than having to move your foot from accelerator to the brake and back all the time, or than up- and down-shifting all the time. In any case, in traffic or on a long boring road, you'd have adaptive cruise control engaged, freeing your foot from accelerator and non-emergency brake duties -- the EAP is very good at using accelerator/regen (plus brakes if required) to control the car.


----------



## JeffC

For information, the EV1 had an explicit "coast down" mode. It was a button on the side of the shifter. When "coast down" was engaged, regen was totally deactivated. The car could literally coast. 

EV1 had a drag coefficient of 0.19 (significantly lower than Model 3, which is probably the lowest drag car currently produced). When coasting downhill at above 75 mph, EV1 would actually accelerate above 80 mph due to the extremely low drag.

Our Toyota built RAV4 EV has two regen modes, EB and B. EB has slight regen off throttle. B has much stronger regen off throttle, like a low gear in a combustion car, for slowing on a steep downhill. These are somewhat similar to Tesla's Low and Standard Regen respectively, though a bit lighter.

Both cars have regen fully integrated with friction braking on the brake pedal.

They also have slight regen simulating automatic transmission drag when the throttle is released. (Regen on throttle)


----------



## JeffC

garsh said:


> Coasting is always going to be more efficient than regen. Having to hold the accelerator at the "correct point" to get coasting is a PITA - I can see the appeal in having an explicit coasting mode to rest the right leg.


Yes, coasting is maximally efficient whenever you don't actually need to slow down. If you do need to slow down, regen is much more energy efficient than friction brakes, which are 100% wasted energy. One definitely does not want to use regen, then accelerate as that has round trip losses.

That said, Tesla's regen on throttle does have a dead zone in the middle of the pedal travel where it will coast. That was by deliberate design, so it is possible to coast a Tesla. It does require some sensitivity to consistently find that dead zone.

Another way to do coast is to have slight or no regen on the throttle, and have the regen integrated with the brake pedal. Most EVs and hybrids do this instead of the heavy regen on the throttle that Tesla does.


----------



## JeffC

Bernard said:


> If you've driven stick-shift cars with clutch, you know that you anticipate slowdowns and stops by downshifting, more than once if needed, before starting to use the brakes. In that same vein, think of the Tesla as a car that has a huge number of "gears" and constantly "shifts" up and down to maintain optimal performance -- and whenever the "downshift" is made in order to slow down the car, it really means regen.
> I never liked automatic transmissions, not even those with optional up-and-down shifters, as they could never offer the fine touch of the gerar+clutch, and feared that EV driving might resemble a bad automatic transmission. But it's quite the opposite with a Tesla: the regen is great and almost always just what you need (and of course the acceleration is almost independent of slope, load, and current speed, the variables that forced you to change gear in an ICE car).


EVs (mostly) have a single speed gear and very low driveline lash (slop), therefore they are very easy to drive and instantly responsive. Also they don't have flywheels to spin up, driveshafts, crakshafts, pistons, connecting rods, etc., all of which add lash and inertia (slop and delays) to responses.


> I don't see how. At the end of coasting, you'll have to brake, often harder than regen can provide and so use the actual brakes, thus wasting energy; and trying to guess when to stop coasting by getting into regen so at to avoid having to use the brakes is not something you can do that well. The regen system is always going to be more efficient than some kind of coasting.


Briefly, regen is less always efficient than coasting because there are electrical, chemical, and mechanical losses when slowing down using the motor as a generator. There are also losses when taking the energy back out of the battery (chemical), through the electronics and wiring (electrical) and mechanical (since all mechanisms have some friction) when using the motor to accelerate. So using regen then acceleration has losses in both directions.

If the goal is to keep moving and not slow down, then regen and acceleration will always have more losses than coasting.


----------



## JeffC

Bernard said:


> Very simple: 99% of the time, you do *not* use the brakes to brake the car -- you just lift the accelerator pedal some or a lot (which means regen). I never touch the brake pedal in normal driving, except when parking, holding on a hill, or at a traffic stop when I am not in adaptive cruise control or when there is no car ahead of me (and, of course, in real emergency braking, but we all hope that's real uncommon). With practice you'll find you can race up a mountain road without using the brakes for hairpins or any curves -- regen is very strong on level roads or climbing roads. (You may need brake assist to regen when going fast down the same mountain road, however, as regen does not quickly slow down your Model 3 running down the hill at 60mph; but you do not need any braking downhill to maintain any chosen speed that allows you to take the curves ;-)
> Once you drive that way, the regen gain when using the brakes would be tiny and the engineering to enable it another complication for Tesla, so why bother?
> (And if you are determined to beat the Pikes Peak record, which will require you to decelerate as fast as you accelerate, something regen cannot do, then you are no longer into efficiency territory anyway ;-)
> 
> At heart, I think the issue is that you misunderstand what regen in the Tesla does: coasting is automatically "included", in that, whenever the speed you demand via the accelerator is no higher than the speed of the car just coasting down the hill, or when you are "coasting to a stop" (which you do by slowly letting the accelerator pedal up), the car recovers energy. It probably does that far more efficiently than we could ourselves by having some sort of explicit coasting mode -- at least I have been very impressed by its regen capabilities.


You explained how Tesla does it very well.

However, there is more than one way to accomplish this.

Another way to do it, which most other EVs and hybrids use, is to have light regen when lifting ott the throttle to simulate slowing a little due to automatic transmission drag, and to have regenerative braking integrated with the friction braking on the brake pedal. GM, VW, Toyota, Nissan, VW/Porsche/Audi and many others handle regen this way. It is different from how Tesla does it.

On almost all other EVs, when you want to slow down very slightly, you lift all the way off the throttle. When you want to slow more, you press the brake pedal. The first part of braking is provided by regen, and harder braking or coming to a complete stop is done by friction brakes. The large majority of braking is l integrated on one pedal: the brake pedal. In other words, you use the brake pedal to slow down.

Some Tesla drivers (especially who are first time EV drivers; lucky you getting a Tesla as your first EV!) may not be aware that regen on brake is how almost all other EVs do this, if they haven't driven other EVs. Prius also does this. (I mention hybrids not because I think they're better, but because they *can* do regenerative braking. In fact, regen was one of the major advantages of hybrids over non-hybird combustion cars since it helps make them more efficient than non-hybrids.)

I do understand that Tesla's way of doing it can become second nature after a while, but it is not the only way to do it, nor is it necessarily better. For more information and history see earlier in this thread or: http://www.jeffchan.com/cars/ev/regen-on-throttle.html


----------



## garsh

Bernard said:


> I don't see how...The regen system is always going to be more efficient than some kind of coasting.


Then you haven't coasted correctly.  If you plan on coasting, then you either don't start off at such a high speed, or you start slowing down a lot sooner than you otherwise would.

Someone ran some real-world tests on his Model S to determine at what speed regen becomes more efficient than coasting (due to aerodynamic losses). That speed ends up being 81mph.
https://forums.tesla.com/forum/forums/those-interested-regen-vs-coasting-i-measured-it


----------



## JeffC

I should note that in some states it's illegal to coast out of gear (i.e. in neutral), since in principle the vehicle is not under control of either the motor or brake. An EV in (drive) gear but coasting is arguably slightly different. Don't know if anyone has tested it in court, but it also probably doesn't come up very often.


----------



## EValuatED

Fascinating debate. Lots of great points and opinions. As a Gen2 Volt driver I can tell you the blended regen+braking works adequately-until it suddenly doesn't - as @garsh noted. When encountering a bump or icy/slick patch, etc., you can momentarily loose the blended regen. Pretty jarring when you first encounter this effect. (With perhaps a contribing factor of the LRR tires that are standard.) So you have to learn to be prepared for it (and potentially have to brake harder, suddenly, than you would otherwise would have to). Pro is the blending and getting regen, coupled with otherwise lighter regen as a standard setting. Con is as described above. Can be lived with. It's a compromise. Note that some Volt owners use the "L" (lower gear simulated) to "gear brake," or, all the time for higher mpge. Shift to neutral to coast is occasionally done. The "L" driving behavior more like Tesla's approach. I do this in stop & go traffic as it keeps me from having to brake as much, with a side effect of less brake wear. Anyway, just sharing a blended regen car owner's observations & opinions.


----------



## Twiglett

Wow is this thread STILL going?
You people really are determined to prove the other side wrong


----------



## MelindaV

I think this has been debated well longer than any of us were interested in, and have every possible positive/negative. Let’s move in.


----------



## PNWmisty

JeffC said:


> Our Toyota built RAV4 EV has two regen modes, EB and B. EB has slight regen off throttle. B has much stronger regen off throttle, like a low gear in a combustion car, for slowing on a steep downhill. These are somewhat similar to Tesla's Low and Standard Regen respectively, though a bit lighter.
> 
> Both cars have regen fully integrated with friction braking on the brake pedal.


It's no wonder the Rav4 EV is somewhat similar since it was a partnership between Tesla and Toyota that developed the RAV4 EV. But the RAV4 EV was never known for its excellent braking. BMW is known more as a "drivers car". Aaron Singer, BMW product planning and strategy manager for electric vehicles had this to say when asked about their strategy for regenerative braking:



> Feedback from the MINI E field trial clearly indicated our driver's preference for aggressive regenerative braking coupled with the ability for "one pedal driving.


This comment, from an EV industry insider who has done the necessary research, makes it clear that one pedal driving is a necessary feature for any EV that aspires to satisfy the driver. Of course, that doesn't preclude them from offering a selection (like Tesla does on the Model 3 with their Standard or Low Regen) or taking it one step further and also offering the ability to map some or all of the regen on the brake pedal. However, the latter option will add cost/complexity to the vehicle and significant additional development time. In the future I imagine all EV's will offer all kinds of options. But in the present, I like Tesla's "KISS" approach that satisfies 99% of drivers with a simple, software only, two-mode regen setting. And making aggressive regen on the throttle, AKA "one pedal driving", the standard default option. This is good.



> They also have slight regen simulating automatic transmission drag when the throttle is released. (Regen on throttle)


Yes, next year I understand they will offer simulated exhaust smells to make the EV experience more familiar for consumers accustomed to driving ICE vehicles.:tmi:


----------



## PNWmisty

JeffC said:


> I should note that in some states it's illegal to coast out of gear (i.e. in neutral), since in principle the vehicle is not under control of either the motor or brake.


Arcane laws like that shouldn't be used to shape the driving behavior of EV's. Besides, EV's have no ability to disconnect the motor from the wheels so they are always in gear!


----------



## fsKotte

MelindaV said:


> I think this has been debated well longer than any of us were interested in, and have every possible positive/negative. Let's move in.


Pro Tip: If you're not interested in a thread, don't follow/read it. Problem fixed!


----------



## garsh

fsKotte said:


> Pro Tip: If you're not interested in a thread, don't follow/read it. Problem fixed!


That's not really an option for moderators.


----------



## fsKotte

Bernard said:


> At heart, I think the issue is that you misunderstand what regen in the Tesla does: coasting is automatically "included", in that, whenever the speed you demand via the accelerator is no higher than the speed of the car just coasting down the hill, or when you are "coasting to a stop" (which you do by slowly letting the accelerator pedal up), the car recovers energy. It probably does that far more efficiently than we could ourselves by having some sort of explicit coasting mode -- at least I have been very impressed by its regen capabilities.


Actually, I do actually completely and fully understand what regen in the Tesla does. It's that I would prefer to have an option to map more regen to the brake pedal and off the throttle. It's what I like, even after driving my M3 for the better part of 2,000 miles in "standard" one-pedal mode (because I have to, it's the only way in this car that you can get regen braking, but it's all on the throttle, which I don't find as awesome as most seem to find it).

I actually find myself switching from "low" to "standard" depending on whether I'm cruising on the freeway (where I find it particularly annoying to have to constantly adjust to "coast" in Standard regen mode) or in a more street/stop&go situation (where regen on the throttle is fine).

One Genuinely New Thought:
Instead of proposing mapping a new "paddle"-like regen control to the steering wheel (a la Volt/Bolt) or getting the Tesla team to develop (at some indeterminate cost) a new regen-on-brake solution/option, I'd just suggest as a compromise, a way to easily/quickly switch from low to standard regen modes . As it stands now, it's a submenu off the main "car" icon menu option on the screen. It's cumbersome to go two menus deep to get to the option and switch (and I've tried just keeping that menu up on the screen, but then you can't see the map/directions, which can be an issue for obvious reasons) If it was something that could easily/quickly be switched on the fly, it would avoid even a penny spent on developing a regen on the brake solution, but would at least let folks more easily/quickly switch from "low" to "standard". This could be done by either putting a software switch on-screen nearer the "top" of the menu structure, or having a setting/option that maps standard/low switching to one of the steering wheel switches.

The appeal of this solution, to me, is that (a) it wouldn't entail any expense/effort in developing regen on the brake, and (b) it simply takes the two pre-existing options and makes them more immediately accessible for the driver to move from one to the other. Under this solution, I'd be able to get my coasting via simple release of the throttle when cruising ("low" regen), while at least being able to easily switch back to the "standard" mode when I do need to decelerate, when not in a cruising situation.

I know, I know - so so many love the one-pedal situation that they don't care or are actually hostile (for some reason) to any idea of adding an option to put regen on the brake, or changing anything - at all - to the current regen set up on all Tesla models. Good for you, but keep in mind, it's a preference. It's sort of like criticizing someone who has a different "favorite" color - what's the point of that?


----------



## fsKotte

garsh said:


> That's not really an option for moderators.


Ah, ok. Guess it's the Burden that a moderator must bear, then!


----------



## Dr. J

fsKotte said:


> I actually find myself switching from "low" to "standard" depending on whether I'm cruising on the freeway (where I find it particularly annoying to have to constantly adjust to "coast" in Standard regen mode)


Two words: Cruise. Control.

I do like your choice of color, however. 

"It's sort of like criticizing someone who has a different "favorite" color - what's the point of that?​*Blue / Aeros (removed) | LR/PUP only for now | 05/30/18 delivery*


----------



## fsKotte

Dr. J said:


> Two words: Cruise. Control.
> 
> I do like your choice of color, however.
> 
> "It's sort of like criticizing someone who has a different "favorite" color - what's the point of that?​*Blue / Aeros (removed) | LR/PUP only for now | 05/30/18 delivery*[/QUOTE
> 
> Nope. Cruise Control does not solve the problem. But I appreciate the input (and am happy you like my color choice)!


----------



## JeffC

PNWmisty said:


> It's no wonder the Rav4 EV is somewhat similar since it was a partnership between Tesla and Toyota that developed the RAV4 EV. But the RAV4 EV was never known for its excellent braking.


Actually our RAV4 EV is the original one built by Toyota. It's not the more recent one where Tesla supplied the drivetrain and battery pack to Toyota. Our RAV4 EV has regen integrated with the brake pedal. It does not have heavy regen on throttle lift unless the stronger regen is selected on the shift lever. That's probably intended for downhill braking on a steep grade, like being in low gear going downhill on an ICE.

All aspects of driving the original RAV4 EV are excellent for a small SUV. Good braking, acceleration, handling, steering, etc. It is not a sporty sedan.


> This comment, from an EV industry insider who has done the necessary research, makes it clear that one pedal driving is a necessary feature for any EV that aspires to satisfy the driver. Of course, that doesn't preclude them from offering a selection (like Tesla does on the Model 3 with their Standard or Low Regen) or taking it one step further and also offering the ability to map some or all of the regen on the brake pedal. However, the latter option will add cost/complexity to the vehicle and significant additional development time. In the future I imagine all EV's will offer all kinds of options. But in the present, I like Tesla's "KISS" approach that satisfies 99% of drivers with a simple, software only, two-mode regen setting.


Original e-Mini used regen on throttle is because BMW hired AC Propulsion to build the electric drivetrains, etc. for it. AC Propulsion also built the T-Zero which the original Tesla Roadster is based on. Roadster uses AC propulsion motor, controller, etc. AC Propulsion is where Tesla got heavy regen on throttle. It's also where the laptop battery cell came from for Tesla. Basically AC Propulsion's work on AC drivetrains and battery packs was a blueprint for Tesla.

AC Propulsion is my friend of a friend Alan Cocconi.


----------



## JeffC

PNWmisty said:


> Arcane laws like that shouldn't be used to shape the driving behavior of EV's. Besides, EV's have no ability to disconnect the motor from the wheels so they are always in gear!


Yes, technically an EV is always in gear. However it's whether the transistors are active that's probably the best analogy for being in gear on an ICE. When the transistors are not active, or when they allow the motor to move freely, there's no positive control of the motor. That would be equivalent to being out of gear on an ICE.


----------



## JeffC

Dr. J said:


> Two words: Cruise. Control.
> 
> I do like your choice of color, however.
> 
> "It's sort of like criticizing someone who has a different "favorite" color - what's the point of that?​*Blue / Aeros (removed) | LR/PUP only for now | 05/30/18 delivery*


I like the blue color too. 

I confirmed with Tesla that cruise control maximizes the use of regen, when it's needed. This is visible on the energy graph on Model S and X and may be visible on the energy bar on Model 3. (TBH one probably should not be looking at the screen when the cruise control is braking however; maybe have a passenger do it.)

Certainly I plan to use Traffic Aware Cruise Control (TACC) for most mundane highway driving, bumper to bumper traffic, etc.


----------



## JeffC

fsKotte said:


> Instead of proposing mapping a new "paddle"-like regen control to the steering wheel (a la Volt/Bolt) or getting the Tesla team to develop (at some indeterminate cost) a new regen-on-brake solution/option, I'd just suggest as a compromise, a way to easily/quickly switch from low to standard regen modes . As it stands now, it's a submenu off the main "car" icon menu option on the screen. It's cumbersome to go two menus deep to get to the option and switch (and I've tried just keeping that menu up on the screen, but then you can't see the map/directions, which can be an issue for obvious reasons) If it was something that could easily/quickly be switched on the fly, it would avoid even a penny spent on developing a regen on the brake solution, but would at least let folks more easily/quickly switch from "low" to "standard". This could be done by either putting a software switch on-screen nearer the "top" of the menu structure, or having a setting/option that maps standard/low switching to one of the steering wheel switches.


That's definitely doable, but it's probably better to not be changing those modes too often while driving. Safer and simpler to have regen on the brake pedal. Want to slow? Press the brake. I think we agree about that. 

A solution would be to offer regen integrated with the brake pedal *as a selectable option* on the regen control panel as suggested earlier. Would be nice to have that choice.


----------



## PNWmisty

JeffC said:


> Yes, technically an EV is always in gear. However it's whether the transistors are active that's probably the best analogy for being in gear on an ICE. When the transistors are not active, or when they allow the motor to move freely, there's no positive control of the motor. That would be equivalent to being out of gear on an ICE.


For legal purposes of arcane laws like the one where it's illegal to coast in neutral, EV's are always in gear. Because if the EV is moving, the motor is turning.


----------



## PNWmisty

JeffC said:


> Roadster uses AC propulsion motor, controller, etc. AC Propulsion is where Tesla got heavy regen on throttle. It's also where the laptop battery cell came from for Tesla. Basically AC Propulsion's work on AC drivetrains and battery packs was a blueprint for Tesla.
> 
> AC Propulsion is my friend of a friend Alan Cocconi.


If I'm understanding you correctly, the circle of friends your friends hang with are the ones that determined regen belongs on the throttle. If so, I agree with that circle of friends on that point, regen is best on the throttle for a street-legal car


----------



## JWardell

I have to admit I've been ignoring this thread since the title alone was enough to upset me, but couldn't imagine why it kept popping up. I finally popped in to see why and am thoroughly enjoying @JeffC 's stories of the EV1 and Alan Cocconi. Its a car I longed for as a kid in high school and college and love reading anything to do with these early EV pioneers


----------



## PNWmisty

JWardell said:


> Its a car I longed for as a kid in high school and college and love reading anything to do with these early EV pioneers


Early EV pioneers? Ummm, I think that was these guys:


----------



## JeffC

JWardell said:


> I finally popped in to see why and am thoroughly enjoying @JeffC 's stories of the EV1 and Alan Cocconi. Its a car I longed for as a kid in high school and college and love reading anything to do with these early EV pioneers


Alan is very much at the center of modern EVs. He deserves much credit for being where we are now, but he would probably never seek that credit for himself.

(I've moved my response to a new thread on general:

https://teslaownersonline.com/threads/who-is-alan-cocconi-and-why-does-he-matter-to-the-modern-ev.7701/

Enjoy!)

EV1 was an incredible car, and its excellence is a strong part of the reason Tesla exists. See: http://www.jeffchan.com/cars/ev1/


----------



## JeffC

PNWmisty said:


> If I'm understanding you correctly, the circle of friends your friends hang with are the ones that determined regen belongs on the throttle. If so, I agree with that circle of friends on that point, regen is best on the throttle for a street-legal car


Yes, they're in my circle of friends, and I'm not afraid to say they got regen wrong. It's best on the brake pedal and almost every other EV does it that way, for some reasons I've already mentioned.

My understanding of regen on throttle is that Alan did it because it was expedient. He did not have the significant engineering resources needed to integrate it with the brake pedal, as GM, Toyota, VW, Nissan and basically all others have done.

And yes, I do understand how heavy regen on throttle lift can be useful. I also understand its downsides.


----------



## fsKotte

JeffC said:


> That's definitely doable, but it's probably better to not be changing those modes too often while driving. Safer and simpler to have regen on the brake pedal. Want to slow? Press the brake. I think we agree about that.
> 
> A solution would be to offer regen integrated with the brake pedal *as a selectable option* on the regen control panel as suggested earlier. Would be nice to have that choice.


Yes, a selectable option for regen on the brake pedal would be the best. And if so implemented, everybody who likes one-pedal still gets it. And those of us who understand regen on brake, and/or who simply like it better, would just select our option. Everybody wins. What's wrong with that?


----------



## fsKotte

JWardell said:


> have to admit I've been ignoring this thread since the title alone was enough to upset me,


Yikes. Sorry to upset you!

I really didn't think this thread would elicit severe emotions. It was a fairly straighforward question/issue, I thought (and still think).

But, look, if it upset you, so be it. Let me be the first to apologize.


----------



## JeffC

fsKotte said:


> Yes, a selectable option for regen on the brake pedal would be the best. And if so implemented, everybody who likes one-pedal still gets it. And those of us who understand regen on brake, and/or who simply like it better, would just select our option. Everybody wins. What's wrong with that?


Absolutely nothing. Agree it would be excellent.


----------



## fsKotte

PNWmisty said:


> Early EV pioneers? Ummm, I think that was these guys:


. . . I was always more of a Detroit Electric man, myself . . . !


----------



## Dr. J

fsKotte said:


> . . . I was always more of a Detroit Electric man, myself . . . !


Yeah, sure, but you can't be "Sought After Because Right" as a marketing slogan! 
("Buying a Car is one thing, being satisfied with your purchase is another." Gold! Pure gold!)


----------



## fsKotte

Dr. J said:


> Yeah, sure, but you can't be "Sought After Because Right" as a marketing slogan!
> ("Buying a Car is one thing, being satisfied with your purchase is another." Gold! Pure gold!)


I don't get it!

Not being clever/funny here, it's just literally - whoosh - right over my head I think. . . . . Was that the old Detroit Electric's slogan?


----------



## JWardell

fsKotte said:


> Yikes. Sorry to upset you!
> 
> I really didn't think this thread would elicit severe emotions. It was a fairly straighforward question/issue, I thought (and still think).
> 
> But, look, if it upset you, so be it. Let me be the first to apologize.


Please don't take most things I post literally with a serious attitude! 

I meant to say I couldn't understand how the argument was going on for so long (without looking) and had avoided it.


----------



## fsKotte

JWardell said:


> Please don't take most things I post literally with a serious attitude!
> 
> I meant to say I couldn't understand how the argument was going on for so long (without looking) and had avoided it.


Understood, though at first I wasn't sure so my apology was sincere! I got it now . . . . all good!


----------



## Dr. J

fsKotte said:


> I don't get it!
> 
> Not being clever/funny here, it's just literally - whoosh - right over my head I think. . . . . Was that the old Detroit Electric's slogan?


I could try to explain myself, but that *definitely* wouldn't be funny. Maybe you have to be 140 years old to get the joke.


----------



## garsh

Dr. J said:


> I could try to explain myself, but that *definitely* wouldn't be funny.


So.... no difference then.


----------



## Model3P75D

fsKotte said:


> I just learned that my M3 (as I believe all Teslas) does not use any regen when I apply the brake pedal.
> 
> This surprised me, as I've had previous EV's that do use some regen when you hit the brake pedal, and I found it to be pretty efficient in utilizing the battery (coast and use no/less energy when you could, and then always use regen when you needed to scrub some speed, via "brake" pedal).
> 
> Anybody know why Tesla has chosen to not use any additional regen when you hit the brake pedal? This is interesting to me because I always thought the most efficient way to drive an EV would be to have the ability to coast when you can, and then regain some energy via regen when you need to slow down. I get that "One Pedal" driving can be fun, but I don't get how it's more efficient, when the regen is always on, and so you're never coasting, always applying energy/electricity to keep the car moving . . . .
> 
> I'm sure I'm missing something here, so appreciate any enlightenment. . . .


I'm quite experienced with electric cars like Chevy volt and Sprecifically Tesla's which I own both S and 3 models. They all have regen. Braking, but if you want to maximize the energy savings, then you customize it in the settings. Turn off the creep and maximize regen braking. And It's not always on, despite what you think. When the throttle is pushed even slightly, the regen stops, and when you let go, it slows the car down so it partially regenerates the electricity used to move the car to begin with, and recharges the Battery. It also saves your brake pads. Typically an electric car, driven properly, doesn't need brake work for well over 100,000 miles! Insane? Not really, just practical.


----------



## Model3P75D

fsKotte said:


> I just learned that my M3 (as I believe all Teslas) does not use any regen when I apply the brake pedal.
> 
> This surprised me, as I've had previous EV's that do use some regen when you hit the brake pedal, and I found it to be pretty efficient in utilizing the battery (coast and use no/less energy when you could, and then always use regen when you needed to scrub some speed, via "brake" pedal).
> 
> Anybody know why Tesla has chosen to not use any additional regen when you hit the brake pedal? This is interesting to me because I always thought the most efficient way to drive an EV would be to have the ability to coast when you can, and then regain some energy via regen when you need to slow down. I get that "One Pedal" driving can be fun, but I don't get how it's more efficient, when the regen is always on, and so you're never coasting, always applying energy/electricity to keep the car moving . . . .
> 
> I'm sure I'm missing something here, so appreciate any enlightenment. . . .


Also, to use the regen braking, don't hit the brakes, gently punch and watch the green bar on top showing how much regeneration is going on.


----------



## fsKotte

Model3P75D said:


> I'm quite experienced with electric cars like Chevy volt and Sprecifically Tesla's which I own both S and 3 models. They all have regen. Braking, but if you want to maximize the energy savings, then you customize it in the settings. Turn off the creep and maximize regen braking. And It's not always on, despite what you think. When the throttle is pushed even slightly, the regen stops, and when you let go, it slows the car down so it partially regenerates the electricity used to move the car to begin with, and recharges the Battery. It also saves your brake pads. Typically an electric car, driven properly, doesn't need brake work for well over 100,000 miles! Insane? Not really, just practical.


Yes, right - I think you accurately described how the Tesla all-throttle regen works.

My OP here is about Tesla's decision to put regen only on the throttle (where it regens when you lift off the throttle a bit) versus putting regen on the brake pedal (so when you depress the brake pedal, some - or all - of your slow-down is due to regen and not pad friction).

You're experienced with electronic vehicles (as am I - my Model 3 is my 3rd), and specifically you drove a Volt, which as you know puts some regen (maybe all, not sure if they have any regen on the throttle) on the brakes rather than just on the throttle, where Tesla puts 100% of it. You also know that the Volt, at least the 2nd gen, has a regen paddle on the steering wheel, which enables you to actually regen using the paddle (Bolt has this, too). I like that set-up and wish there was an option to set the Model 3 that way, too. But there isn't; that's life.

To sum up this entire thread - I wish Tesla had an option to map regen to the brake pedal, and away from the throttle, because that's how I enjoy driving EV's the most.

Further summation: Lots of people like the regen on the throttle, but I and a few others don't as much, and to each his own.


----------



## fsKotte

Model3P75D said:


> Also, to use the regen braking, don't hit the brakes, gently punch and watch the green bar on top showing how much regeneration is going on.


You highlight another item I wish my Model 3 had - an accurate display of the energy being recovered. The green line indicates that it's happening, and a long green line means more regen, a shorter green line means less regen occurring. But it seems it wouldn't be much to actually show the kwh's being recovered, real-time. Other EV's show this, it's not a big deal.

Note: I love my M3. And one of the things I really really like (as most any Tesla owner likes), is the fact that it can and will improve over time, via those OTA updates. So, my criticisms/request about the way they map regen, and the ask for more regen detail that elaborates on the little green line, are not complaints per se, but rather areas I'd hope Tesla might improve as time goes on.


----------



## PNWmisty

fsKotte said:


> To sum up this entire thread - I wish Tesla had an option to map regen to the brake pedal, and away from the throttle, because that's how I enjoy driving EV's the most.


You might be a candidate for the Porsche Taycan if you prefer two-pedal driving (regen blended into the brake pedal) instead of the method Tesla uses (brake pedal only operates the brakes). I say you "might" be a candidate because, to date, no one has successfully blended regen with the brakes that didn't result in complaints from race drivers that the braking wasn't consistent and didn't offer good feel. That tends to happen when you put a computer between your foot and your brakes.

Hopefully, Porsche will finally figure out how to do this well for the minority who think they want it. Because it looks like Jaguar has decided it belongs on the right foot with their new iPace.


----------



## JeffC

fsKotte said:


> You highlight another item I wish my Model 3 had - an accurate display of the energy being recovered. The green line indicates that it's happening, and a long green line means more regen, a shorter green line means less regen occurring. But it seems it wouldn't be much to actually show the kwh's being recovered, real-time. Other EV's show this, it's not a big deal.
> 
> Note: I love my M3. And one of the things I really really like (as most any Tesla owner likes), is the fact that it can and will improve over time, via those OTA updates. So, my criticisms/request about the way they map regen, and the ask for more regen detail that elaborates on the little green line, are not complaints per se, but rather areas I'd hope Tesla might improve as time goes on.


Agree on both points, though I think too much display of stats could be distracting. We really want drivers to be looking out at the road and not the displays.


----------



## Model3P75D

Model3P75D said:


> Also, to use the regen braking, don't hit the brakes, gently punch and watch the green bar on top showing how much regeneration is going on.


It seems that at higher speeds the model 3 will regenerate energy by braking. I noticed too, that at lower speeds (around town) the braking pedal doesn't add to regenerative braking. Not sure why. The model S does. I know that because I've been driving it for two years. A Very reliable badass car. I must say!


----------



## JeffC

Model3P75D said:


> It seems that at higher speeds the model 3 will regenerate energy by braking. I noticed too, that at lower speeds (around town) the braking pedal doesn't add to regenerative braking. Not sure why. The model S does. I know that because I've been driving it for two years. A Very reliable badass car. I must say!


Tesla integrates regenerative braking only with the throttle. It does not integrate regenerative braking with the friction braking on the brake pedal at all. Almost all other EVs and hybrids do.

Here's some history for why that may be: http://www.jeffchan.com/cars/ev/regen-on-throttle.html


----------



## garsh

Model3P75D said:


> ... the braking pedal doesn't add to regenerative braking. Not sure why. The model S does.


No it does not.


> I know that because I've been driving it for two years.


----------



## fsKotte

dm3 said:


> I've had both the Spark EV and the 500e, both of which have regen on brake. I never had any problems with braking and would never have known regen and friction brakes were blended if I hadn't read about it. Until I saw this thread, I thought that's how the Model 3 behaved.
> 
> The Spark has a version of "low" and "standard" regen, and after testing both out extensively I prefer "low". i can coast (most efficient) and still regen (brake pedal) when I need to. I get the best of both worlds. No friction brakes needed if I don't slow to a stop.
> 
> I can also do what fsKotte asked for which is to quickly switch between the two quickly because the modes are selected by the gear shifter. I can switch very quickly to standard regen on downhills using muscle memory. (Just like changing to Low gear on an automatic transmission.) I can then switch out of it just as quickly, all without having to take my eyes off the road. I would also like to be able to switch as easily on my Model 3.
> 
> The Spark also has a display showing instantaneous power consumption and regen power in kW. I don't find it distracting. In the beginning I would switch between low and standard regen on downhills to see how much of a difference it made in kW, but now I forget it's there.


What I've been doing lately, is when I'm just getting on the freeway and I know it's fairly smooth sailing (no traffic) and I'm going to be on that freeway for a number of miles, I touch the lower left "car" button, then into the Driving menu, and switch to Low regen on the fly (which requires driver attention to go two menu levels deep to get to this option) and then do the same procedure to switch back to Standard regen when I'm exiting the freeway or start to hit traffic. It's a workaround, but it works and it's definitely more efficient (and fun for me) when cruising at highway speeds. I get no errors or warnings that on-the-fly regen settings changing is detrimental to the vehicle, so I assume it's ok to do this (if it was bad for the car, they could disable it when the vehicle is moving, or have a warning menu pop up, as they do with so many other things, but they've chosen not to do any of that.). So you can really cruise when you're cruising, and then go back to Standard regen on surface, stop/go streets (or if traffic starts to develop on the freeway).

Of course, the main problem with this workaround is that you have to go two menus deep to get to it. That's not convenient, and it requires driver attention away from the road a little bit (so not really super-safe). Would be better if this regen setting was put on the main screen, or have a regen setting/option that puts it on the main menu, should you want it to be there.

In fact, I have written to Tesla, via the "suggestions" email, and requested that, at the very least, they have an option in the regen settings where you can move the ability to switch between Standard and Low to the "top" menu so you don't have to fiddle with the screen to get to it. I'd suggest that anyone else who would like this feature/option to send an email to suggest it to Tesla. Obviously, they listen to us owners, as they've incorporated a number of user/owner suggestions into their updates. So if you'd like it, let them know!

PS - What I like about this option/proposal, is it avoids having to go through the engineering/expense to put regen on the brake, and makes it a relatively easier prospect of just remapping/adding a pre-existing software option. The end result is that it gives the driver the a much safer way to choose the option of "cruising" at freeway speeds, and gaining that coasting dynamic that you get with low regen, for those who want it (and I believe when cruising on the freeway, with no stop/go issues in front of you, coasting is more efficient than constant regen on the throttle anyway, and I for one love that "magic carpet" feeling of just coasting like that, in low regen mode).


----------



## fsKotte

Here's what I wrote to Tesla, BTW:

Hi,

One thing I and a certain number of other M3 owners have mentioned on the various forums, is a desire to be able to safely switch between Standard and Low regen on the fly (while driving), as I and these other folks really enjoy that "magic carpet" feeling of coasting that you get on "Low" regen, when it's practical to do so (i.e., when cruising without traffic on a freeway or any other road). We also like Standard regen in stop/go and surface street situations, so we find ourselves switching between low and Standard regen typically at least a couple of times as we're driving.

Currently, I achieve this by going to the two-menu-deep "Driving" sub menu and making the switch between Standard/Low as I see fit. But this is just a bit too distracting, and likely a little unsafe (you have to look/aim to be sure you touch the right thing, to navigate into the menus, as you know).

I'd like to suggest, then, that on that Driving sub-menu there is an option/check-box to additionally map that Standard/Low regen switch to a top/main menu location, so you could make the switch between Standard/Low regen on the fly right from that top/main menu.

This would make the task of switching between Standard/Low much safer and easier, as it would require far less driver attention by reducing all of that navigating we currently have to do to get to the regen option.

Bottom line, I love the Standard regen setting when I find myself needing to stop with some frequency (e.g., surface streets, stop/go traffic, or blasting down some fun windy roads). But when cruising on a freeway where there's no traffic ahead, the "Low" regen setting really opens up that "magic carpet" feeling as it seems you just fly/coast with almost no effort (well, that's the feeling I get!).

Thanks for your time and consideration on this!

Best,
[fskotte's real name goes here]

PS - As a brief side-note, this first came up as a result of some owners finding that the regen being only on the throttle (and not at all on the brake pedal) was not as pleasant, to them, as having the regen activated by depressing the brake pedal, with less regen happening with a release of the throttle. Understanding that re-mapping regen onto the brake pedal would likely be expensive and time-consuming, my current suggestion is I think a workaround that would achieve most of the benefits of less regen on the throttle, when it makes sense to do that, while avoiding any re-engineering costs of actually putting regen on the brake pedal. By just adding a mapping of the regen switch to an easy-to-access, less distracting availability, this solves this problem at far less cost, it seems. . . .


----------



## fsKotte

fsKotte said:


> Here's what I wrote to Tesla, BTW:
> 
> Hi,
> 
> One thing I and a certain number of other M3 owners have mentioned on the various forums, is a desire to be able to safely switch between Standard and Low regen on the fly (while driving), as I and these other folks really enjoy that "magic carpet" feeling of coasting that you get on "Low" regen, when it's practical to do so (i.e., when cruising without traffic on a freeway or any other road). We also like Standard regen in stop/go and surface street situations, so we find ourselves switching between low and Standard regen typically at least a couple of times as we're driving.
> 
> Currently, I achieve this by going to the two-menu-deep "Driving" sub menu and making the switch between Standard/Low as I see fit. But this is just a bit too distracting, and likely a little unsafe (you have to look/aim to be sure you touch the right thing, to navigate into the menus, as you know).
> 
> I'd like to suggest, then, that on that Driving sub-menu there is an option/check-box to additionally map that Standard/Low regen switch to a top/main menu location, so you could make the switch between Standard/Low regen on the fly right from that top/main menu.
> 
> This would make the task of switching between Standard/Low much safer and easier, as it would require far less driver attention by reducing all of that navigating we currently have to do to get to the regen option.
> 
> Bottom line, I love the Standard regen setting when I find myself needing to stop with some frequency (e.g., surface streets, stop/go traffic, or blasting down some fun windy roads). But when cruising on a freeway where there's no traffic ahead, the "Low" regen setting really opens up that "magic carpet" feeling as it seems you just fly/coast with almost no effort (well, that's the feeling I get!).
> 
> Thanks for your time and consideration on this!
> 
> Best,
> [fskotte's real name goes here]
> 
> PS - As a brief side-note, this first came up as a result of some owners finding that the regen being only on the throttle (and not at all on the brake pedal) was not as pleasant, to them, as having the regen activated by depressing the brake pedal, with less regen happening with a release of the throttle. Understanding that re-mapping regen onto the brake pedal would likely be expensive and time-consuming, my current suggestion is I think a workaround that would achieve most of the benefits of less regen on the throttle, when it makes sense to do that, while avoiding any re-engineering costs of actually putting regen on the brake pedal. By just adding a mapping of the regen switch to an easy-to-access, less distracting availability, this solves this problem at far less cost, it seems. . . .


Tesla replied to my above email. Here's what they said - it's encouraging:

Hello [fsKotte],

Thank you for reaching out to us here at the Executive Care Team. Tesla is always curious our customer's ideas on improving the Tesla experience in accordance with our goal to built the best cars in the world. 

*Your idea sounds like one that could bring us closer to this target, therefor I have submitted this as a feature request to our development team.* For future feature requests and ideas like these or any customer support needs please feel free to reach out directly to our customer support teams at: [email protected].

Thank you for taking the time to provide us with your valued feedback.

*With kind regards*
*Bettina Haerten | Global Executive Care*
Burgemeester Stramanweg 122 | 1101EN Amsterdam


----------



## JeffC

@fsKotte If I may ask, did you use that same email address to contact them originally, or something else? I'd like to formally put in my request for regen on brake pedal option. I believe it would be a strong and technically correct *optional setting*.


----------



## fsKotte

JeffC said:


> @fsKotte If I may ask, did you use that same email address to contact them originally, or something else? I'd like to formally put in my request for regen on brake pedal option. I believe it would be a strong and technically correct *optional setting*.


JeffC - I signed into my Tesla account, clicked through the "Manage" button, and clicked on "Ask a Question", and then checked the "Report to Tesla Management Team" box when I sent my message. Here's a screenshot of what I see after I log in and then click the "manage" button:










Hope this helps!


----------



## JeffC

fsKotte said:


> JeffC - I signed into my Tesla account, clicked through the "Manage" button, and clicked on "Ask a Question", and then checked the "Report to Tesla Management Team" box when I sent my message. Here's a screenshot of what I see after I log in and then click the "manage" button:
> 
> View attachment 12838
> 
> 
> Hope this helps!


Thanks much! Looks like I don't have those buttons yet, since I don't have delivery. Will try the email address she mentioned (and also use the button later when I get the car).

P.S. Also request that you please do a feature request for a regen on brake *option*. I hope that more people asking would increase the possibility that it might happen.


----------



## fsKotte

JeffC said:


> Thanks much! Looks like I don't have those buttons yet, since I don't have delivery. Will try the email address she mentioned (and also use the button later when I get the car).
> 
> P.S. Also request that you please do a feature request for a regen on brake *option*. I hope that more people asking would increase the possibility that it might happen.


Sure, I'll do one for regen on brake - no prob!


----------



## JWardell

I have a question. You've seen me complain about the weak regen before. I noticed the power graph never shows more than 75% regen. It's like it totally knows it can regen harder but you can't have it! Has anyone else noticed this? Is there some corner case where I can get it to 100%?
Tesla really needs to uncork the fun on both acceleration and regen.


----------



## fsKotte

JWardell said:


> I have a question. You've seen me complain about the weak regen before. I noticed the power graph never shows more than 75% regen. It's like it totally knows it can regen harder but you can't have it! Has anyone else noticed this? Is there some corner case where I can get it to 100%?
> Tesla really needs to uncork the fun on both acceleration and regen.


Sorry - no idea how to increase regen.

Suggest you make a suggestion to Tesla directly, as I did re mapping the Standard/Low regen switch to a more accessible/top-level location on the main screen. You can make this submission through your Tesla account, see my screencap above . . . . You'll likely get a response back. I did, practically same day!


----------



## JeffC

JWardell said:


> I have a question. You've seen me complain about the weak regen before. I noticed the power graph never shows more than 75% regen. It's like it totally knows it can regen harder but you can't have it! Has anyone else noticed this? Is there some corner case where I can get it to 100%?
> Tesla really needs to uncork the fun on both acceleration and regen.


There is a programmed deceleration limit on regen, probably due to some of the issues mentioned in my paper below. Regen is probably also lessened at high speeds for similar reasons.

Somewhat related: when the battery is full, regen is much less available. This is due to battery physics. When a cell is full, it's unable to accept much more charge from regen.

That is another reason why regenerative braking should be integrated with friction braking on the brake pedal. If so, when regen is less available and regen and friction are on the brake pedal, then pressing the brake pedal harder will simply engage more friction braking for you. I.e., it does the right thing, even when regen is less available.

I added this as a section to my paper caller "More Consistent Braking" at:

http://www.jeffchan.com/cars/ev/regen-on-throttle.html


----------



## garsh

JeffC said:


> That is another reason why regenerative braking should be integrated with friction braking on the brake pedal. If so, when regen is less available and regen and friction are on the brake pedal, then pressing the brake pedal harder will simply engage more friction braking for you. I.e., it does the right thing, even when regen is less available.


But in the process, the braking "feel" is changed. It's not a panacea.

I'd still like a big resistor so we can have dynamic braking when the battery's full. No need to wear out the brake pads.


----------



## EValuatED

garsh said:


> But in the process, the braking "feel" is changed. It's not a panacea.
> 
> I'd still like a big resistor so we can have dynamic braking when the battery's full. No need to wear out the brake pads.


Could be used to heat the car's interior or have a deployable radiator like some sci-fi spaceXcraft...


----------



## JeffC

garsh said:


> But in the process, the braking "feel" is changed. It's not a panacea.


Agree there can be some difference in feel between regenerative braking and friction braking.

But the bigger picture issue, which may be far more important, is that the driver is trying to command braking, and with regen on throttle, with a full pack, they don't get the expected regen and must switch over to the brake pedal. That change can be unexpected, and as an additional mode, is objectively an ergonomic flaw. More modes is generally less ergonomic. When the goal is simply to slow down, fewer modes is less complex and simpler to use with regen on the brake pedal.

This does not negate the benefits of one pedal driving, but does highlight a situation where it creates a more complex and arguably less desirable outcome.


----------



## JWardell

garsh said:


> But in the process, the braking "feel" is changed. It's not a panacea.
> 
> I'd still like a big resistor so we can have dynamic braking when the battery's full. No need to wear out the brake pads.


Just redirect the power to the cabin heater, regardless of temperature!


----------



## fsKotte

JeffC said:


> Agree there can be some difference in feel between regenerative braking and friction braking.
> 
> But the bigger picture issue, which may be far more important, is that the driver is trying to command braking, and with regen on throttle, with a full pack, they don't get the expected regen and must switch over to the brake pedal. That change can be unexpected, and as an additional mode, is objectively an ergonomic flaw. More modes is generally less ergonomic. When the goal is simply to slow down, fewer modes is less complex and simpler to use with regen on the brake pedal.
> 
> This does not negate the benefits of one pedal driving, but does highlight a situation where it creates a more complex and arguably less desirable outcome.


I had this exact experience over the weekend. I charged to 100% because I was expecting a lot of driving on Saturday, and of course there was no regen on the throttle out of the gate (at full charge). Since I've been using "standard" regen a fair amount, especially on "street"/stop-go driving situations, the first few times I rolled up to a stop sign were a bit unsettling, since I was expecting/used to more slowing just by releasing the throttle a bit. But there was *no* regen, and so I had to hit the brakes much more so than I was used to. I re-adjusted after a few more braking events, and of course as I put another ten or so miles on the car, regen returned. But it was weird at the outset, sorta felt like my brakes had partially gone out.


----------



## PNWmisty

JeffC said:


> @fsKotte I'd like to formally put in my request for regen on brake pedal option. I believe it would be a strong and technically correct *optional setting*.


Technically correct??? 

Even Jaguar's iPace has regen on the right foot. And if regen on the brake pedal was "technically correct", why wouldn't it be the* default* setting? Oh, that's right, because most drivers like it on the right! Even the professional driver with Road and Track putting the Performance Model 3 through some hot laps on the track thought the regen on the right was pretty cool.


----------



## JeffC

fsKotte said:


> I had this exact experience over the weekend. I charged to 100% because I was expecting a lot of driving on Saturday, and of course there was no regen on the throttle out of the gate (at full charge). Since I've been using "standard" regen a fair amount, especially on "street"/stop-go driving situations, the first few times I rolled up to a stop sign were a bit unsettling, since I was expecting/used to more slowing just by releasing the throttle a bit. But there was *no* regen, and so I had to hit the brakes much more so than I was used to. I re-adjusted after a few more braking events, and of course as I put another ten or so miles on the car, regen returned. But it was weird at the outset, sorta felt like my brakes had partially gone out.


Yes, that's correct, and many people have experienced it in Teslas that are charged to nearly full. Regen is much less then.

That said, generally one should charge to 80 or 90%. 100% is almost never needed, including for long road trips, since the Superchargers are about 100 miles apart, and generally should not be used. All Lithium ion batteries will last longest if the charge range is kept relatively narrow:

https://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries

(There are many academic papers about this, but none particularly easy to find online. Some are referenced above.)


----------



## fsKotte

JeffC said:


> Yes, that's correct, and many people have experienced it in Teslas that are charged to nearly full. Regen is much less then.
> 
> That said, generally one should charge to 80 or 90%. 100% is almost never needed, including for long road trips, since the Superchargers are about 100 miles apart, and generally should not be used. All Lithium ion batteries will last longest if the charge range is kept relatively narrow:
> 
> https://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries
> 
> (There are many academic papers about this, but none particularly easy to find online. Some are referenced above.)


Yes, I get what you say, totally. I'd love to find the time to fully read and digest the article you linked, but boy is it long, and at the moment, I can't devote the attention and time it deserves. However, as a bottom-line sort of proposition, I get the idea generally from what I have managed to read in the literature on this, that charging to somewhere between 70-90% is best for the health and longevity of the battery. I have mine almost always set to around 75% charge limit. Only when I anticipate a lot of driving, usually on the weekend, do I set that significantly higher. I think I've set it at 100% only three times so far, after around 2,700 miles (so that's three out of about a 75 charges that have gone higher than 75/80%, since I charge every night, like most do). I think that's probably ok, I think.

I do understand the superchargers situation. But understand that I was just driving locally, but driving a lot, on these 100% days; i.e. it wasn't a "long-range" drive from SF to LA or anything like that - just big distances, all over the SF bay area. I still haven't even used a supercharger yet, haven't had the need.

Part of why I had those three episodes of 100% charging, was because nothing soothes the range anxiety like having a boatload of miles in reserve, and as I'm new to the long-range car experience, I just wanted to make sure I didn't end up heading home with just barely enough miles to make it. I've had it with such situations, after having a 500e and Leaf, both of which had short ranges and constantly had me checking to make sure I could eke out enough to get back home (one was worse than the other - guess which) .

In fact, each time I did charge to 100, and even though I criss-crossed the SF Bay Area a number of times and was all over west Marin, and basically drove about as much as I could possibly drive in a given day, I always ended up still with around 100 miles left. So now I know, extended-bay-area-locally at least, no matter how much I drive in a given day, I've got p-l-e-n-t-y of buffer even at below 100% charge. So, probably from now on, I'll go 90% on local big-driving days, just to keep the battery better conditioned.

You noted 80-90% as a good target for charging. Here's an article from Electrek that points to 70% charge being a good idea. I don't go quite that low, though . . .

https://electrek.co/2017/09/01/tesla-battery-expert-recommends-daily-battery-pack-charging/


----------



## fsKotte

PNWmisty said:


> Technically correct???
> 
> Even Jaguar's iPace has regen on the right foot. And if regen on the brake pedal was "technically correct", why wouldn't it be the* default* setting? Oh, that's right, because most drivers like it on the right! Even the professional driver with Road and Track putting the Performance Model 3 through some hot laps on the track thought the regen on the right was pretty cool.


Well, ok, sure. But realize I did say that I *believe* it to be so. That would make it an opinion, right? I still believe that to be the case, and you don't believe that. So that's the state of things, which is fine.

In addition, this:

*Your Q*: "[W]hy wouldn't [regen on the brake] be the *default* setting?
*My A*: I don't care what's the default setting. I just want an *option* to put it on the brake - default, secondary, tertiary, do not care where you put it or what you think of it, as long as it's there. (alternatively, as I've noted in previous posts above, if there was just a safer way to switch from Standard to Low on the throttle without changing the brake config, I could live with just that). And crucially, there's no reason you can't have regen on both pedals, which would be fine with me, and which brings me to the next part of this very concise, brief post (!):

It's interesting you bring up the Road and Track iPace article, because it's clear that the iPace puts at least some regen on the brake, and from the sound of the article, you can't opt out of that. But it does have the option of low/high regen on throttle, just like Teslas.

And that's actually a key point, because when you read the R&T article carefully, you realize the regen on the brake, whether you deem it to be imperfect and/or "spooky", did not seem to impede the author's fun one wit, in using the max regen on the throttle on his track runs. In fact, he unequivocally said he did have a blast on the track with throttle regen, and also said he barely used his brakes on the track when set up this way. Importantly, this was his experience, *even with regen on the brake. He said this in the article*:

"_There was one section of road where everything clicked. With its beautiful chassis tuning, ample power, instant torque, precise steering, and regenerative braking, I got into a lovely flow with the I-Pace._"

So if the R&T guy could have such a dreamy experience, even with that "spooky" brake regen lurking just a brake-push away all the while, then why the concern about having an option to *additionally* put some regen on that brake pedal? Note, when the author mentions "regenerative braking" in the quote above, he was clearly talking about using the throttle regen as brake, not using the actual brake pedal - so in other words pretty much driving it with the same set-up as our Teslas have under Standard regen, EXCEPT . . . . the brakes still had regen on them, though he found he didn't use the brake pedal almost at all (because he set the car to high throttle regen).

And probably most importantly, in spite of the author's criticisms of how the brake regen is designed/implemented, he was careful to specifically point out that "*they never let me down*."

So what does this mean, or at least what conclusions can we draw from that R&T test drive article? It means that regen on the brakes (realize you still can put it on the throttle, too - that's always been the case) detracts *pretty much nothing* from the fun that regen-on-the-throttle folks enjoy. All it does, is add an *option* of going low on the throttle regen, and *still* getting some regen on the brakes, for those who might want that combo in certain situations. It illustrates perfectly how even regen on the brake that's not quite perfect can co-exist with high regen on the throttle and still deliver an equally large boatload of fun. It's clearly not an either/or situation.

Tesla has some clever engineers - they'd probably come up with the best regen-on-brake pedal implementation the world has ever known if they tried. But, even with the iPace's purportedly imperfect implementation, using the high regen on throttle setting provided that dreamy experience the R&T author described, even in the presence of some regen on the brake.

I should probably just stop here, but for better or for worse, I probably won't . . . . . nope . . . . . looks like I'm forging ahead, so here goes:

Lastly, in terms of defaults, I'm not convinced of the default-must-be-the-best argument. Something's gotta be the default setting, when it comes out of the factory, right? Should the default be the "best" one, or . . . the most popular? It's not unreasonable to decide that the *popular* setting probably should be the default setting, if it's anticipated that most would want it, and nobody's arguing that the throttle regen isn't popular. But is it better? I don't care, though I know what I prefer.

And, as I said, if Tesla would do nothing with the brake and simply provide an option to additionally remap the Standard/Low switch to the main/default/top menu so it's safer to access and change on the fly, I think I'd just take that and be done with it, as a good compromise for my preferences.


----------



## PNWmisty

I like the firm and consistent hydraulic brake pedal feel when I need to haul her down in a hurry. I'm afraid it would be impossible to achieve the same feel if some of the brake was reserved for regen. Because the brake is not simply a pedal position sensor like the throttle, it's a mechanical/hydraulic unit with an electro-hydraulic booster built in for self-driving, TACC and Automatic Emergency Braking. Currently the feel is excellent during emergency braking and I wouldn't want to give that feeling up. 

If it could magically be done without adding a more vague feel to the brake pedal then fine, but I doubt it wouldn't have some effect.


----------



## fsKotte

PNWmisty said:


> I like the firm and consistent hydraulic brake pedal feel when I need to haul her down in a hurry. I'm afraid it would be impossible to achieve the same feel if some of the brake was reserved for regen. Because the brake is not simply a pedal position sensor like the throttle, it's a mechanical/hydraulic unit with an electro-hydraulic booster built in for self-driving, TACC and Automatic Emergency Braking. Currently the feel is excellent during emergency braking and I wouldn't want to give that feeling up.
> 
> If it could magically be done without adding a more vague feel to the brake pedal then fine, but I doubt it wouldn't have some effect.


Sure, I get that, totally.

And in my mind, if anybody could make that magic happen, it'd probably be Tesla engineers. And if they did take a stab at it, and made it an *option* for the brake, then we'd both win. You could set your brake to full hydarulic all the time, while I'd have mine probably always set to regen on brake and then switch from high to low regen on throttle as needed (low throttle regen mostly for cruising at speed, with few impediments in front). Problem solved, Courtesy of Tesla's Magic. 

After almost 3,000 miles in the Model 3, I find my specific use-case for low throttle regen / brake pedal regen is the cruising thing, where I mostly need the brake regen to slow down when stuff in front of me starts to get slower. Otherwise, it's a magic carpet feeling of just almost perpetual motion coasting, that is difficult to replicate with high regen throttle setting. I find that coasting/floating feeling of the low regen to be just about as fun and thrilling as twisty roads on the high regen throttle setting.

And for surface street/stop-go driving, I do use the Standard regen almost always to good effect, and have no qualms. So, it's really the cruising / magic carpet thing for me.

And if there is a concern that the engineering cost to try to make some of that magic happen is too high, you could do nothing else other than put some regen on a paddle (a la the volt/bolt, to name a few) or put it on one of the roll-y wheel switches on my M3, so I can use regen-on-demand to slow down in a cruise situation when I had to, and that's really all you'd actually need to do for me. Change nothing else other than that. . . . .


----------



## PNWmisty

fsKotte said:


> After almost 3,000 miles in the Model 3, I find my specific use-case for low throttle regen / brake pedal regen is the cruising thing, where I mostly need the brake regen to slow down when stuff in front of me starts to get slower. Otherwise, it's a magic carpet feeling of just almost perpetual motion coasting, that is difficult to replicate with high regen throttle setting. I find that coasting/floating feeling of the low regen to be just about as fun and thrilling as twisty roads on the high regen throttle setting.


I get that also. But that magic carpet feeling of just almost perpetual motion coasting is completely doable as the car is now. Just set regen to high (or low) and when you want to coast as far as possible, hold the throttle pedal in the "neutral" position, neither applying power nor regen. The Model 3 is impressive in it's ability to coast. Of course this takes slightly more skill than simply releasing the throttle completely (if there was no regen on the throttle) and that is why I think a detent at that neutral throttle position would be a good idea. I also think the throttle mapping should be adjusted to have a slightly larger "neutral" position.


----------



## fsKotte

PNWmisty said:


> I get that also. But that magic carpet feeling of just almost perpetual motion coasting is completely doable as the car is now. Just set regen to high (or low) and when you want to coast as far as possible, hold the throttle pedal in the "neutral" position, neither applying power nor regen. The Model 3 is impressive in it's ability to coast. Of course this takes slightly more skill than simply releasing the throttle completely (if there was no regen on the throttle) and that is why I think a detent at that neutral throttle position would be a good idea. I also think the throttle mapping should be adjusted to have a slightly larger "neutral" position.


*TL;DR Executive Summary:*
Standard Regen just does not work for this cruising/magic carpet thing. It's difficult to stay in equilibrium and really does not give the coasting feel, even if technically it might be sort of coasting when you do manage to keep it perfectly balanced. It's unsatisfying and awkward. But Low Regen works great, and requires no precise balance to achieve the coast/magic carpet feel. It's what I do and I love it.
BUT, *there is no way to dynamically increase regen when needed while in Low*, and therein lies the problem. So that's why it would be ideal for my preferences to either (1) add an option for regen on the brakes, (2) add a dynamic regen on a paddle like the Volt/Bolt/others have (tough, I know - means new hardware), (3) map dynamic regen to one of the M3 steering wheel rolly-switches, or (4) additionally map the Standard/Low switch to a safer, more easily accessible top-level menu location. Bottom line, you can't dynamically adjust regen resistance - you have to pick either Standard/Low and you get what you get, and that switch is not convenient where it is currently in the menu tree (not really dynamic, but might be the easiest to implement and would work for me). That's not ideal.

*Full Essay Here: *

I find it difficult, distracting and unsatisfying, to try to get that balance in the High-regen Standard setting, so I just don't use it for that. And it seems, feel-wise, that it just doesn't have that same coast/MagicCarpet feeling even when I do achieve a perfect green bar/black bar zero balance position under Standard regen. Hard keep it there, too. Big hassle, ultimately unsatisfying and not really a coasting feel at all to me.

But Low Regen setting. Indeed, the magic carpet feeling is fully achieved for me in Low Regen mode, and especially at freeway speeds, you still get that feeling, even if you've got some green bar showing (regen), or black bar (battery use) peeking out. With Low, it really doesn't have to be anywhere close to actual equilibrium to get that coasting feel, because, after all, it's in Low Regen mode. So that's what I do - I switch to Low Regen and Enjoy The Carpet Ride when I can/cruise. Not having to constantly keep an eye on the equilibrium helps to make Low Regen way more fun and satisfying for such cruising, to me.

But, when traffic in front slows unexpectedly, and I've been cruising in Low Regen, sometimes Low Regen isn't enough to slow down and I have to hit those mechanical brakes - i.e., *there's no way to dynamically increase regen while in Low, when needed*. That's when having either regen on the brakes, a regen switch mapped to the steering wheel (a la Volt/Bolt, etc), OR at least an additional mapping of Standard/Low switch (so it sits at a top menu location) would really bring it home and complete the experience for me.

Also, I think at highway speeds, regen on the brakes presents fewer problems with feel - you're mostly scrubbing off just a bit of your momentum, just adjusting your speed to keep distance from the cars in front, or start to slow a bit for traffic. In my experience, it's when you're needing to use brakes for a full-on stop, that the weird/different feel of the regen-on-brake comes into play. (I know, I know - keeping a specific distance and slowing for traffic is what TACC is for - but TACC is wrapped up in EAP, which I did not purchase. Just a little annoyed that TACC isn't standard and separate from EAP, at the $50k pricepoint. But that's another story/post, maybe . . . .)

But in any event, yes, Low-Regen brings the Magic Carpet Feeling, but most importantly Low Regen does this even without the driver having to come close to feathering it to perfect energy in/out equilibrium, precisely because it is in fact low regen. And it's what I use. Standard Regen falls far short for this sort of cruising, even when you're able to get it in that perfect equilibrium state (and it just doesn't really feel like a coast in that situation, especially since it can so easily come out of that perfect equilibrium that's needed to even achieve coasting).

But then, as it stands I can't dynamically increase regen while in Low, and so I must switch back to Standard to get more regen slow-down. Therefore, a way to either quickly switch to Standard, or add an additional way to apply regen (either through the brake, or additionally mapping an easily/safely accessible separate software switch to go Standard) would seal the deal . . .


----------



## BostonPilot

garsh said:


> But in the process, the braking "feel" is changed. It's not a panacea.
> 
> I'd still like a big resistor so we can have dynamic braking when the battery's full. No need to wear out the brake pads.


I was going to say the same thing... I really don't like systems with blended friction and regen - I always feel like the braking is inconsistent where it makes the transition from regen only to regen+friction.

I have been caught on my old BEV where I left with the battery fully charged and expected regen and got nothing, so I totally get the safety issues. (I've also had it due to low temperature). But, like garsh says, that's why we need dynamic braking 

I'd also like to be able to dial the regen up more... I can see limiting to .2 G for the person who may not be used to regen, but I think the BMW approach to one pedal driving is good and I'd like that option.


----------



## JeffC

BostonPilot said:


> I was going to say the same thing... I really don't like systems with blended friction and regen - I always feel like the braking is inconsistent where it makes the transition from regen only to regen+friction.


It depends how well it's done. On the first generation Prius, the integration between regenerative and friction braking on the brake pedal was poor. By the second generation Prius, it was greatly improved. On our 2002 Toyota RAV4 EV built by Toyota and not Tesla, which we drive nearly every day, the regen is integrated with friction braking on the brake pedal and it's nearly seamless. On both versions of the GM EV1 the integration was much better than Prius, but not quite as good as RAV4 EV.

On Leaf, the integration is good. On Chevy Volt, the integration is good. On VW E-Golf the integration is good.

If Tesla were to make regenerative braking OPTIONALLY available on the brake pedal, I'm certain they could do a good job at it. Their engineering is at least as good as those other companies.


----------



## garsh

JeffC said:


> On Leaf, the integration is good.


I strongly disagree. I'm very used to Nissan's implementation. It's the one that makes me prefer Tesla's choice.


----------



## JeffC

garsh said:


> I strongly disagree. I'm very used to Nissan's implementation. It's the one that makes me prefer Tesla's choice.


To be honest, I only took a test drive of a Leaf. What problems did you find with it? Is there a noticeable change then friction is engaged? (If so, then I'd probably argue it has an inferior implementation, as opposed to there being something wrong _in principle_ with having both regenerative and friction braking integrated with the brake pedal.)


----------



## MelindaV




----------



## JWardell

MelindaV said:


>


Are you saying that the Nissan Leaf brakes feel like pushing wood into a horse carcass? That's probably pretty accurate.


----------

