# Regen braking in traffic



## arts711 (Feb 24, 2019)

Hi everyone, 

Wondering what tips or techniques people here with using regen traffic in traffic. Sometime regen is enough to slow down, other times, i realize I'm not slowing down enough and need to hit the brakes harder than i used to in an ice car. Also, if traffic starts moving or you want to change lanes, let go of the brakes, there's still regen and getting going is just overall jerky.

What do you guys to smooth out this experience or do you just switch it to low regen temporarily to help comfort?

Thanks!


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## JasonF (Oct 26, 2018)

I trained first on Low Regen, and practiced forcing regen by using low acceleration. After that, Standard Regen is easier to learn.


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## Frully (Aug 30, 2018)

When you release the friction brake yes, the regen is still on...you just have to partially depress the accelerator enough to get back up to coast. It doesn't apply regen WHEN you let go of the brakes...it regens the whole time the accel is off.


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## GeoJohn23 (Oct 16, 2018)

Or flip on TACC and set your desired follow value and let the car do the work...


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## SoFlaModel3 (Apr 15, 2017)

It really just becomes second nature. I don’t ever think about it and rarely ever touch my brakes approaching a red light until I need to complete the stop from 2-3 MPH


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## Bigriver (Jan 26, 2018)

Regen is something I just had to relearn how to drive to keep from being jerky. It does become second nature and I now dislike driving without it. But also, are you aware of the dashed green line that lets you visually see how much Regen is limited? It helps me know in advance when Regen isn't going to be as strong as usual.


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## ADK46 (Aug 4, 2018)

I live far from any stop-and-go traffic, but I don't think I'd need the friction brakes often, just to come to a full stop and hold it. 

When I frequently faced stop and go traffic years ago, I came to the conclusion that it was often caused by oscillations - the stopping occurs on a standing compression wave (high car density). If only the "molecules" would behave differently, it might be avoided. I tried to be a dampener of these oscillations, while others were clearly excitors. Dampening comes from looking well past the car in front, anticipating a slow-down. The worst excitor reacts to just the car in front, late, leading to high compression forward, and aft since the following drivers must brake harder than they would otherwise. It's also important to react instantly to the subsequent speed-up; reacting late leads to rarefaction, a trough of low car density that further increases the amplitude of the wave. 

(What else is there to do while stuck in traffic but think about things? I was on my way to work at a place that designed jet engines, swarming with aerodynamicists. I did not invent this concept, actually - it's an established way to think about traffic jams.)

Anyway, my advice to all commuters is a dampener thou shalt be. 

Is TACC a dampener?


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## garsh (Apr 4, 2016)

Bigriver said:


> Regen is something I just had to relearn how to drive to keep from being jerky.


^ this.

It takes practice. You'll develop new habits as you get used to the car.


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## JasonF (Oct 26, 2018)

Using TACC for daily driving can actually be kind of dangerous.

I believe the OP was asking about how to _smooth out _their use of regen. I think the best way to do that is still to start out with Low Regen mode for a while.


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## MelindaV (Apr 2, 2016)

JasonF said:


> Using TACC for daily driving can actually be kind of dangerous.


how so?

IMO, TACC (or autosteer) gives you the ability to spend more of your visual concentration to watch the adjacent lane's cars and if any will be merging in front of you (or swerving unintentionally), cars coming down a freeway onramp needing to merge, other road hazards, etc. Compared to when not using TACC (or autosteer) you spend most of your visual concentration on the car directly in front of you and whatever you have left is given to watch the adjacent lane's cars.

In the 6 months I've been driving with TACC/Autosteer, I find its following skills to be pretty stellar. Yes, there are a few times I've hit the brakes myself, but more because old habits are still there. It this point my trust level of its ability to safely follow another car is equal to, or honestly probably higher, than my own.


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## MelindaV (Apr 2, 2016)

and on regen, I've never driven a 3 on low regen  (or chill or creep for that matter). I am of the mindset that you should jump right in and learn it. Starting with low with the intent of moving to standard means you need to relearn it when 'ready' for standard.


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## FRC (Aug 4, 2018)

MelindaV said:


> (or swearing unintentionally)


Damn those vehicles and their unintentional swearing!!


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## MelindaV (Apr 2, 2016)

FRC said:


> Damn those vehicles and their unintentional swearing!!


autocorrect (obviously, right?)


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## Ed Woodrick (May 26, 2018)

So, let's take it to the extreme first. The 2018 Leaf has the ePedal. The ePedal is a one pedal solution that controls both acceleration and braking. Unlike the Tesla, when you lift your foot off the ePedal, you come to a complete and total stop. The ePedal uses both regen and braking in a combined, very smooth fashion (I wish that Tesla would have added regen to braking). If, the ePedal is not coming to a stop fast enough, a brake exists and you use it as always, but in most driving, you just use the ePedal to modulate the speed

With regen, you learn to modulate your speed with the pedal. If you want to coast, you don't take your foot off of the accelerator, you just press a little less. Then as you slow down, you have to match the speed with removing the foot off of the pedal. After driving a little bit, it just becomes second nature. The big thing that you learn is then in non-regen, you learn how far away to remove the foot from accelerator when stopping and then when to apply the final braking. With regen, you keep your foot on the pedal a LOT longer and then release it to come to a stop by applying final braking.

The difference being that you don't ride your brakes when decelerating, as you probably do when driving a car without regen (yea, I know, you don't ride your brakes, but come up to a traffic light and see how long your foot was on that brake before stopping, it may surprise you)

So, jerky is just because you haven't learned to modulate the accelerator. You don't take your foot off, like in other cars, you modulate the speed. If the deceleration to a stop is too quick, then slowly remove accelerator pedal, don't pull foot off.

But, remember, whenever you use the brakes, you get no regen. Regen is your friend and can attribute 30% or more to your range.


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## JasonF (Oct 26, 2018)

MelindaV said:


> how so?


I pictured that advice to cause people to turn on TACC practically the moment they back out of the driveway, and follow the entire route to work and back that way, never actually touching the accelerator or brake. Naturally that could cause inattentive driving, running red lights, and making people who need to merge into traffic angry.

Also I feel it's better to learn how to regen by yourself, so you can get a better understanding of how it works. I learned how to use Low Regen first, and was getting 230-250 wh/mi average, and now 180-220 wh/mi Standard Regen. I drive on highways here at 80 mph, and accelerate quickly, so I'm not even remotely hypermiling. And I'm in Florida where there's not much hope of downhill regen. But I do try to suck as much energy as I can out of slowing down for traffic and lights, and that takes some practice.


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## PNWmisty (Aug 19, 2017)

Ed Woodrick said:


> But, remember, whenever you use the brakes, you get no regen. Regen is your friend and can attribute 30% or more to your range.


If you are braking with your right foot, like most of us do, you will always have the full amount of available regen working while using the brakes. Regen does not turn off simply because you activated the friction brakes.


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## garsh (Apr 4, 2016)

Ed Woodrick said:


> But, remember, whenever you use the brakes, you get no regen.


The brake pedal in a Tesla doesn't add any _additional_ regen. Once your foot is off of the accelerator, you've maximized your regen.


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## Long Ranger (Jun 1, 2018)

ADK46 said:


> I live far from any stop-and-go traffic, but I don't think I'd need the friction brakes often, just to come to a full stop and hold it.
> 
> When I frequently faced stop and go traffic years ago, I came to the conclusion that it was often caused by oscillations - the stopping occurs on a standing compression wave (high car density). If only the "molecules" would behave differently, it might be avoided. I tried to be a dampener of these oscillations, while others were clearly excitors. Dampening comes from looking well past the car in front, anticipating a slow-down. The worst excitor reacts to just the car in front, late, leading to high compression forward, and aft since the following drivers must brake harder than they would otherwise. It's also important to react instantly to the subsequent speed-up; reacting late leads to rarefaction, a trough of low car density that further increases the amplitude of the wave.
> 
> ...


This is exactly my philosophy in stop-and-go traffic, and it's why I shut off TACC in heavy traffic. I think TACC as it exists today is an excitor, not a dampener. It doesn't seem to look beyond the car ahead to anticipate a slowdown. It also comes to a complete stop just a bit too abruptly at the end.

When driving without TACC, I find I can drive this car more smoothly than any other car I've ever driven. As others have said, the regen just takes a little practice and then it feels really natural.


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## SoFlaModel3 (Apr 15, 2017)

MelindaV said:


> and on regen, I've never driven a 3 on low regen  (or chill or creep for that matter). I am of the mindset that you should jump right in and learn it. Starting with low with the intent of moving to standard means you need to relearn it when 'ready' for standard.


I'm a firm believer in this!!


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## MJJ (Aug 7, 2016)

ADK46 said:


> Anyway, my advice to all commuters is a dampener thou shalt be.
> 
> Is TACC a dampener?


TACC is an exciter. AP is a (poor) lane shopper. Between the two, oy vey! But I have confidence they will improve.

I like your description of traffic patterns in terms of oscillation. Have thought of it that way for years but never so concisely. I've tried to be a dampener also. You know who else are dampeners? Trucks. In slow traffic, I like to get behind one, turn on AP, and start fiddling with the radio or get up and mix a drink.


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## Frully (Aug 30, 2018)

I've done as others suggested that creating a separate nearly-identical driver profile with CHILL enabled for stop and go traffic. It makes TACC/AP in stop and go MUCH smoother by being a tad slower to respond with accel.



MJJ said:


> TACC is an exciter. AP is a (poor) lane shopper.


I find it works as a damper so long as you can set the speed low enough. If below 30km/h (minimum) then it definitely can excite without chill enabled.


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## MJJ (Aug 7, 2016)

Frully said:


> I've done as others suggested that creating a separate nearly-identical driver profile with CHILL enabled for stop and go traffic. It makes TACC/AP in stop and go MUCH smoother by being a tad slower to respond with accel.
> 
> I find it works as a damper so long as you can set the speed low enough. If below 30km/h (minimum) then it definitely can excite without chill enabled.


I stand by my observation, and I've had chill mode on exclusively since day one.

Which brings me to another question. What evidence do (or even *can*) we have that the accelerator mode (chill vs standard) affects self driving responses? Harkening back to the dark ages when I got Pixie (October 2018), the reason I tried chill mode was that I hoped it would make autopilot less twitchy. It didn't change anything except the foot response. And reading the manual, I think that's the only claim.

But I do like having the word CHILL on my screen. It's good general advice.


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## Frully (Aug 30, 2018)

MJJ said:


> I stand by my observation, and I've had chill mode on exclusively since day one.
> 
> Which brings me to another question. What evidence do (or even *can*) we have that the accelerator mode (chill vs standard) affects self driving responses? Harkening back to the dark ages when I got Pixie (October 2018), the reason I tried chill mode was that I hoped it would make autopilot less twitchy. It didn't change anything except the foot response. And reading the manual, I think that's the only claim.
> 
> But I do like having the word CHILL on my screen. It's good general advice.


My evidence at this point is largely anecdotal -- but I made the switch yesterday after 6 months of being used to normal accel. GF was in the car and extremely nauseated from an unrelated problem so I wanted the 30 minute commute home to be ...well...chill. It genuinely made a big difference in the accel side of the curve. Not sure if it affected the regen side of the curve but if it did it was because we never got to as high a peak speed before having to slow down again...


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## MelindaV (Apr 2, 2016)

Frully said:


> My evidence at this point is largely anecdotal -- but I made the switch yesterday after 6 months of being used to normal accel. GF was in the car and extremely nauseated from an unrelated problem so I wanted the 30 minute commute home to be ...well...chill. It genuinely made a big difference in the accel side of the curve. Not sure if it affected the regen side of the curve but if it did it was because we never got to as high a peak speed before having to slow down again...


I don't mind how AP accelerates, but would like it to smooth out the braking in stop and go traffic. Oddly, autosteer is much rougher than TACC. youd think both would stop/go the same, but autosteer is much more lurchy

PS - as someone who feels about to throw up 🤢 most days, I appreciate you tried to make the drive better for your GF 👍


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## MJJ (Aug 7, 2016)

Interesting. I’ve resolved to turn on standard mode for a couple of days to investigate. Please stand by!

I *hope* there’s no difference, as I find chill mode so full of lurches, neck-snapping accelerations, and panic stops already.


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## Towerman (Jan 11, 2019)

MelindaV said:


> and on regen, I've never driven a 3 on low regen  (or chill or creep for that matter). I am of the mindset that you should jump right in and learn it. Starting with low with the intent of moving to standard means you need to relearn it when 'ready' for standard.


Totally agree and would like to add how shocked I am (at first) when driving an ICE and I have to actually brake all the time - old school.


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## PNWmisty (Aug 19, 2017)

MJJ said:


> What evidence do (or even *can*) we have that the accelerator mode (chill vs standard) affects self driving responses?


In my experience, "Chill" mode doesn't do anything when using AP or TACC. I've tested it back to back a couple of times and couldn't tell the difference.

When driving manually it appears it puts in a delay to my throttle requests. It seems like it ramps up the throttle request over a short period of time. Since I particularly like the instant throttle control of the Model 3, I leave it on "Standard".


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## MJJ (Aug 7, 2016)

PNWmisty said:


> In my experience, "Chill" mode doesn't do anything when using AP or TACC. I've tested it back to back a couple of times and couldn't tell the difference.
> 
> When driving manually it appears it puts in a delay to my throttle requests. It seems like it ramps up the throttle request over a short period of time. Since I particularly like the instant throttle control of the Model 3, I leave it on "Standard".


There seems to be an impression that chill has wider effects. I'm with you, I haven't seen it. I have a couple ideas about how to demonstrate, maybe I'll make a video.


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## Long Ranger (Jun 1, 2018)

MelindaV said:


> I don't mind how AP accelerates, but would like it to smooth out the braking in stop and go traffic.


I agree, it's the braking that bothers me the most.


MelindaV said:


> Oddly, autosteer is much rougher than TACC. youd think both would stop/go the same, but autosteer is much more lurchy


Just to be clear, when you say autosteer is rougher than TACC, you're just talking about acceleration and braking, nothing related to the steering itself? I hadn't considered that they might be different. I rarely engage TACC only, so I might have to try that.


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## theloneranger08 (Sep 29, 2017)

MJJ said:


> I stand by my observation, and I've had chill mode on exclusively since day one.
> 
> Which brings me to another question. What evidence do (or even *can*) we have that the accelerator mode (chill vs standard) affects self driving responses? Harkening back to the dark ages when I got Pixie (October 2018), the reason I tried chill mode was that I hoped it would make autopilot less twitchy. It didn't change anything except the foot response. And reading the manual, I think that's the only claim.
> 
> But I do like having the word CHILL on my screen. It's good general advice.


You only drive your Model 3 in chill mode? Seems so boring. Not to menion, there's no way I could make the lane changes I need to in Atlanta rush hour traffic in chill mode. I'd get cutoff or hit.


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## MelindaV (Apr 2, 2016)

Long Ranger said:


> Just to be clear, when you say autosteer is rougher than TACC, you're just talking about acceleration and braking, nothing related to the steering itself? I hadn't considered that they might be different. I rarely engage TACC only, so I might have to try that.


correct. it is much smoother when just using TACC. (I've mostly noticed this in stop and go traffic, so may not be as much of a difference when actually moving)


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## MJJ (Aug 7, 2016)

theloneranger08 said:


> You only drive your Model 3 in chill mode? Seems so boring. Not to menion, there's no way I could make the lane changes I need to in Atlanta rush hour traffic in chill mode. I'd get cutoff or hit.


Here, this. Are you saying that the Acceleration setting affects steering? Because that's different from Steering. I did test the modes on my way to work this morning, and a lane change was consistently completed in 8 flashes of the signal, whether in chill or standard Acceleration. Try it; you can switch modes while driving.


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## theloneranger08 (Sep 29, 2017)

MJJ said:


> Here, this. Are you saying that the Acceleration setting affects steering? Because that's different from Steering. I did test the modes on my way to work this morning, and a lane change was consistently completed in 8 flashes of the signal, whether in chill or standard Acceleration. Try it; you can switch modes while driving.


I'm not talking about using autopilot. I'm talking about driving the car yourself. Lol there's no way autopilot could navigate Atlanta rush hour traffic. Mad Max mode isn't aggressive enough. My point is that having much more acceleration at your disposal is much safer than not having it and makes driving (especially changing lanes) easy. Even if you don't floor it each time, wouldn't you want that power at your disposal if needed?


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## ADK46 (Aug 4, 2018)

It just occurred to me that my previous stop-and-go experience was mostly in manual shift cars, in which a full stop is a particular inconvenience. You can't help but be a dampener when there's a clutch and a shifter demanding the use of two extremities, especially if you've got a coffee in your hand. There were times I let the engine race in a low gear to avoid a brief shift into a higher gear - since that produces strong engine braking, lifting off was unwise (no brake light, either). I present this gratuitous bit of knowledge for the benefit of those for whom a third pedal is an effective anti-theft device. I certainly have no worries about leaving the key in my old Unimog:










I must admit that I enjoy frightening people with this image. The moderators may judge it inappropriate for younger viewers.

==============

There was some confusion over "anecdotal" in this or some other thread. It's one of my favorite words, a powerful yet subtle weapon in the scientific community. But I had a mental block to it, so it's written on a note stuck to my monitor. Good to see it here.


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## PNWmisty (Aug 19, 2017)

ADK46 said:


> View attachment 24029
> 
> 
> I must admit that I enjoy frightening people with this image. The moderators may judge it inappropriate for younger viewers.


Oh, no, the frightening thing is not the operation, it's the flushing and replacing of all that hydraulic and gear oil!


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