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Car not coming to a complete stop using hold mode

I don't know what to call this; I tried searching and couldn't find anything similar. Thought I'd share in case it happens/ed to anyone else

A few times now my 2020 Model 3 has stopped braking efforts just before reaching complete stop.
The street I live on ends in a T intersection, and there's a small hill just at the end where the stop sign is.
I typically approach this intersection and take my foot off the accelerator to let regen bring me to a complete stop (like I do most intersections if I can). The car ALMOST reaches full stop, but then it's like someone flipped regen off - the car lurches forward a bit (down the little hill) and I have to hit the brake pedal to keep from rolling into oncoming traffic.

It's jarring; the first time it happened I thought I'd been rear-ended!

It doesn't happen every time, and so far it hasn't happened anywhere else. I put in a service request and so far they've come back asking for the exact location.

Curious if anyone else has experienced this, or has any wild theories. Strangely, I had a similar problem in my old Jeep Cherokee (but of course, that didn't have regen!)
 

Big Earl

bnkwupt
Supporting Member
Jul 12, 2017
7,972
16,039
La Conner, WA
I’ve never been a fan of hold mode. It isn’t particularly smooth, it’s annoying to modulate, and is occasionally inconsistent. I’m a big fan of roll, and modulating the braking myself.

That said, something is up with your car (or perhaps a software bug). It shouldn’t be *that* inconsistent in its behavior.
 

tm1v2

Active Member
Oct 18, 2021
2,427
2,121
USA
@TydalForce Is this a new behavior for your car?

I've not experienced anything like that with my October 2021 M3P in 4k+ miles so far, using Hold the whole time. It's actually very very smooth for me. So I'm also of the mind that something might be wrong with your car, which Tesla service could potentially figure out and fix.

It does really easy up on the deceleration as it closes in on 0mph though. If I were slowing the car myself using brakes, I would spend less time at very low mph than Hold does, even if I was trying to be extra smooth. I've never experienced what you described though.
 
I’ve been using hold as long as I’ve had the car I think (December 2019). It’s always been fine. It never did this until this year, but to be fair we’ve only lived on this street since July.

Pretty sure I’m hitting some bug or fringe scenario they didn’t think to test. But I guess it could be a sensor issue or something.

I’ll definitely let ya know what Service comes up with.
 
Regen cannot get the car to zero, that's just physics.
So Tesla needs to actually back power the motors, or use friction brakes. This clearly works pretty well on flat or uphill roads.
Downhill, this is a tougher transition to make. Like you say, this is probably just catching the edge case of right where the blend has an issue. In Seattle we have lots of hills steep enough that the car will never stop with just regen. I can imagine one right on the edge where regen does slow you down, but where the switch from that to the backpowered motor isn't perfectly smooth, and the reduction in deceleration force actually allows the car to accelerate due to the hill, which would feel pretty weird.

I this literally only happens on one specific hill, I'd doubt it means anything is up with your car.
 
Curious if anyone else has experienced this, or has any wild theories. Strangely, I had a similar problem in my old Jeep Cherokee (but of course, that didn't have regen!)

I had similar events, where I lifted the accelerator pedal expecting regen to slow down the car, only to have nothing happen for around 1 second, and then have regen kick in at regular power. Because you expect regen, it almost feels like the car is accelerating (which it is not). This happened a few times last year, and I did not note any correlation between the location, slope, temperature, charge level, and I did not pursue the investigation. Luckily, it has not happened recently.
 
I've ran into this. it does this on bumpy surfaces.

A few times now, during regen braking, the regen gets reduced during a bumpy segment of the road.
This forces me to apply the brakes, only noticed it at lower speeds (under 20mph).

Not sure if a bug or not.

Also, i've noticed that 'Chill' mode regen is not as quick to take over compared to 'Sport' mode.
There's a delay i think due to the sensitivity reduction on the gauss pedal.
 
The initial service tech didn't find anything obvious in the logs and has sent them up the line for a deeper analysis
I can see the event in my TeslaMate logs, which helped narrow down the timestamp
It's only happened a few times so it's hard to pinpoint a trigger, but it didn't happen before V11, and I also got new tires in December.
 
My battery still has the regen reduced message at 50f also if your battery is full it will turn off regen. Any wheel slip or gravel will also put it in to snow mode and turn off the regen. This morning at 50F mine had the dots to the left for reduced regen.


1649254106415.png
 
My battery still has the regen reduced message at 50f also if your battery is full it will turn off regen. Any wheel slip or gravel will also put it in to snow mode and turn off the regen. This morning at 50F mine had the dots to the left for reduced regen.


View attachment 790609
These are valid points.
Battery was not full; I charge to 80%
It's just pavement there; there was no snow or rain nor is there typically gravel or similar (though I can't say 100% for sure what might have been there).
This isn't a "No Regen at all" situation, but rather "regen was slowing me down as I expected and suddenly without warning was gone" - like someone turned it off just before I stopped.
 
These are valid points.
Battery was not full; I charge to 80%
It's just pavement there; there was no snow or rain nor is there typically gravel or similar (though I can't say 100% for sure what might have been there).
This isn't a "No Regen at all" situation, but rather "regen was slowing me down as I expected and suddenly without warning was gone" - like someone turned it off just before I stopped.
I've felt that with my old Chevy Volt any slight slip like a painted white line it would panic and cut 100% of the regen and you would almost shoot forward. So far I haven't felt anything like that with the M3
 
I don't know what to call this; I tried searching and couldn't find anything similar. Thought I'd share in case it happens/ed to anyone else

A few times now my 2020 Model 3 has stopped braking efforts just before reaching complete stop.
The street I live on ends in a T intersection, and there's a small hill just at the end where the stop sign is.
I typically approach this intersection and take my foot off the accelerator to let regen bring me to a complete stop (like I do most intersections if I can). The car ALMOST reaches full stop, but then it's like someone flipped regen off - the car lurches forward a bit (down the little hill) and I have to hit the brake pedal to keep from rolling into oncoming traffic.

It's jarring; the first time it happened I thought I'd been rear-ended!

It doesn't happen every time, and so far it hasn't happened anywhere else. I put in a service request and so far they've come back asking for the exact location.

Curious if anyone else has experienced this, or has any wild theories. Strangely, I had a similar problem in my old Jeep Cherokee (but of course, that didn't have regen!)
How steep is the hill you are on when it happens? I have a steep driveway (15 to 20 degrees slope) up to my garage and I find Hold does not always behave. When rolling forward down the hill, it does not come to a stop when the accelerator peddle is released. Worse, sometimes hold gives way when the brake peddle is released (with the accelerator still also released). At one point I almost got into an irrecoverable position as there was an obstacle ahead (down hill) and I could not transition to reversing up hill without initially rolling forward closer to the obstacle. Fortunately I caught it just in time to drive out forward turning sharply to the right to avoid the obstacle by just a few centimeters!
 
It's a steep enough hill I suppose; IDK the measurement. Our road comes to an intersection, and it's a bit of a "ramp" down to the connecting street.
It sounds like the same thing to me, there's a sudden grade and maybe full stop is slightly miscalculated and it "slips". Tesla's been analyzing my logs for a couple months now and I haven't heard anything but I haven't experienced the problem in a while either.

Here's a photo from street view that I'm not sure accurately does it justice...

Screen Shot 2022-10-10 at 1.11.09 PM.png
 
Does not look anywhere near as steep as my driveway (mine is a 2022 Model Y, only had it a few weeks). The braking force in Hold mode does seem to depend on the state of charge of the battery - when it is near 100% there is virtually no braking. For some reason it only seems to use regeneration and can't use that when there is nowhere to put the electricity. I do not understand why - it could dump the energy as heat (like the friction brakes do) or it could blend in the friction brakes to give consistent braking force.
 

MP3Mike

Well-Known Member
Feb 1, 2016
20,390
51,630
Oregon
For some reason it only seems to use regeneration and can't use that when there is nowhere to put the electricity. I do not understand why - it could dump the energy as heat (like the friction brakes do) or it could blend in the friction brakes to give consistent braking force.
Current firmware versions have an option to enable blended brakes when the battery can't accept energy from regen.
 

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