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

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garsh

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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

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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... :D
 

JeffC

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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.
 

fsKotte

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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.
 

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@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??? :rolleyes:

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

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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

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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

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Technically correct??? :rolleyes:

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.
 
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PNWmisty

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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

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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. . . . .
 
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PNWmisty

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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

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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 . . .
 
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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 :cool:

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.
 

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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.
 
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JeffC

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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.)