# unexpected change to regenerative braking behavior after minor service



## vafpaloalto (6 mo ago)

After I had the two rear tires replaced at the Tesla Palo Alto (CA, USA) service center, braking performance has dramatically changed. The (former) software engineer in me cannot fathom why this should have occurred as a result of replacing tires.

Since the service, regenerative braking no longer is applied consistently when I release my foot from the accelerator: sometimes it is, sometimes it isn't. This is dangerous and I can find no setting to change back to the old behavior.

In addition, releasing the accelerator to slow to a stop sign or stop sign now usually requires heavy braking and often results in abrupt, collision-avoidance automatic braking behavior.

Yes, I have tried changing the various settings under "Pedals and Steering" as well as under "Autopilot" but have not been able to revert to the old behavior.

No, not applying regenerative braking when I release the accelerator does not appear to be related to battery charge level; the unexpected behavior occurs when the battery is at 90%, the maximum I charge overnight, and at other levels after driving throughout the day.

Has anyone else seen this problem? Have you figured out how to fix it?


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## Ed Woodrick (May 26, 2018)

It should have been doing this all along. At 90% I think that you should be getting the regenerative braking is reduced message. 
Full regen should return as the charge decreases. Check your charge level when it does and doesn't appear. 
I'm not really sure why abrupt braking exists, unless you are panicing when you don't get enough regen. 

While it is easy to get used to, being so reliant on it is dangerous. What if you have to drive someone else's car? 

Does the Pedals & Steering option make ANY difference?


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## Power Surge (Jan 6, 2022)

I know in my car, I have almost no regen when the battery is 90% or more (as per Ed's comment above, I have never gotten any reduced regen message). But you said it's doing it at lower charge levels also. 

I can say that I have noticed similar behavior to what you are describing after certain updates. Is it possible they did an update while it was there?


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## vafpaloalto (6 mo ago)

Hi Ed-

Thanks for the suggestions.

I've tried pretty much every possible option under "Pedals & Steering" and can't find any way to revert to the old behavior.

I am not getting ANY messages about "regenerative braking is reduced". 

And while I might believe it would be reduced when I first leave the house with a 90% charge, it shouldn't be after I've been driving around for a while.

The previous behavior was consistent for more than 4 years. Now it isn't. That is very disturbing because there should have been NO changes to braking performance when the two rear tires were replaced. I can believe that two new tires might have SLIGHTLY changed rolling resistance, but much more than that is happening here.

The previous behavior was also similar to that of a non-EV: you let off the accelerator and the car slowly decelerates due to rolling and wind resistance.






Ed Woodrick said:


> It should have been doing this all along. At 90% I think that you should be getting the regenerative braking is reduced message.
> Full regen should return as the charge decreases. Check your charge level when it does and doesn't appear.
> I'm not really sure why abrupt braking exists, unless you are panicing when you don't get enough regen.
> 
> ...


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## vafpaloalto (6 mo ago)

Thanks also for the feedback and the suggestions.

My M3 is set to install software updates as soon as they become available, so it should already have been up-to-date when I brought it in for tire replacement service.

Not only am I not getting any reduced regen messages, the new behavior is inconsistent: sometimes, the old behavior (green line indicating regen when foot is off the accelerator), sometimes it doesn't (no green line, no regen when foot is off the accelerator). That is what is most disturbing and dangerous: behavior has not only changed but it is inconsistent. 

I tried contacting online support today but the web site grayed out the "let's chat" button even though I was attempting the chat during supported hours.

When I first got my M3 in 2018, support was excellent. I cannot say that is true today.

If anyone knows a functioning email address to contact Tesla support, please share it. Try as I might, I can't find any such email address on tesla.com.



Power Surge said:


> I know in my car, I have almost no regen when the battery is 90% or more (as per Ed's comment above, I have never gotten any reduced regen message). But you said it's doing it at lower charge levels also.
> 
> I can say that I have noticed similar behavior to what you are describing after certain updates. Is it possible they did an update while it was there?


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## bwilson4web (Mar 4, 2019)

Hi,



vafpaloalto said:


> . . . regenerative braking no longer is applied consistently when I release my foot from the accelerator: sometimes it is, sometimes it isn't. . . .
> 
> Has anyone else seen this problem? Have you figured out how to fix it?


It started for me about 5-6 weeks ago along with the local, high heat. Intermittent, it usually clears by the time I get out of my neighborhood. However, the mechanical brakes work fine with a very little more pressure. The problem I have is documenting the problem.

I may start iPhone video recording in the morning and share a YouTube of the problem. For me, it is a relatively easy workaround.

Bob Wilson


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## iChris93 (Feb 3, 2017)

This is because the vehicle is sensing the difference between the four tires and is incorrectly thinking you’re losing traction and reducing regen. This happened in the winter of 18 for many vehicles with winter tires because Tesla hadn’t tuned the software for it. You can see the thread here about it Who has lost regen with winter tires?

I’m surprised Tesla let you replace only two.


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## JasonF (Oct 26, 2018)

I agree with just above - that the new tires have a drastically different traction profile than the older ones, and it’s making the traction control system go a little haywire. You’re not getting errors because traction control believes it’s handling a mixed traction environment normally.


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## garsh (Apr 4, 2016)

@vafpaloalto , did you check the air pressure in all four tires? Are they equal?
What brand, model, and size of tire do you have at each position?


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## Promethious (28 d ago)

We operate four 2022 Teslas. Two 3’s and two Y’s. There have been no services performed on them. All are up to date on software versions. We are in Southern New Hampshire. All of the have the RG cue on when starting out , even if scheduled to prepare the cabin and battery. The cue sometimes will extinguish after a while, sometimes not. The RG braking seems to be working at various degrees. Can anyone pass this onto the mother ship. I believe it’s a software problem. The first car, a 3 we had last winter worked perfectly. Now, not so much.


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