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Regen suddenly limited and nothing changes that

pjscott

Member
Apr 4, 2019
8
1
British Columbia
After a regular charge to 75% and a few days without driving, during which an upgrade to 2019.32.12.2 occurred, my M3 announced that regenerative braking was limited, which indeed it was. By the end of the day it had stopped saying that, but regen was still limited, which can be seen in the display with the left part of the dis/charge bar dotted out. Two days later and after a charge to 80% no difference after soft and hard resets. The warning didn't come back for a few days even though the regen remained and remains limited.

Temperature has not been particularly colder than it was before, when it had never showed limited regen except when I charged over 95%. However this is the first time I've been entering a colder season with the M3, which I got in April. It is kept in a garage (I am on the coast in PNW), temps there haven't dropped below 50F yet. I've tried charging it right up until my departure, didn't make any difference. However, while driving I have seen a couple of times when the dots disappeared, but only briefly, like a flickering, and even when they had disappeared it didn't seem to be decelerating any more.

The one thing I haven't tried yet is charging to 95% so it has a legit reason to limit regen and then seeing if it recovers the way it used to.

The regen limitation has not changed at all during driving. Verified that the setting had not changed from standard. This situation bothers me not for any concerns about the battery, but because I want a consistent behavior when I come off the accelerator for my driving reactions.

Display showing limit: Screenshot, 2019-10-23 22:47:08 - Paste.Pics
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,807
8,424
Boise, ID
It's described in the manual. Every fall when temperatures start getting colder--dozens of these threads asking about the limited regen. Batteries can't be charged as fast when they are cold, so about mid 50's fahrenheit, you will start seeing a little bit of those limitations on regen power. And it will definitely be more and more as temperatures get colder--just the way it is.
 

Sophias_dad

Supporting Member
Supporting Member
Jul 29, 2018
1,543
1,620
Massachusetts
I'm not quite convinced that its entirely temperature related for OP. His picture seems to show more dots than I'm seeing on mine, and I'm starting at 45f these days. Admittedly, to get rid of every dot, I've had to drive pretty hard to get the battery warmed up, even after 10 miles of driving. OTOH, I don't think I've ever seen my AWD 3 regenerate so much as to fill the left part of the bar with green.
 

pjscott

Member
Apr 4, 2019
8
1
British Columbia
Just a couple of data points - when the dots were disappearing yesterday while driving, the whole section was going out and then reappearing a few seconds later. They weren't going out one by one. Also I am pretty sure I have seen the green bar go all the way to the left. I am certain that right now I am not getting as much deceleration.
 

Brian's ReX

Member
Jun 26, 2018
280
342
Seattle
I'm not convinced that it's temp related either. I, too, live in the PNW... keep my X garaged, and the garage is a pretty constant 60-65 degrees. Even says so in the X's dash and in the app. Now, after updating to 32.12.3, I get the regen-limit dots/dashes when I first get in the car - even before opening the garage door.

Well aware that cold weather limits regen. But it had never done it before this update.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
10,905
13,653
San Diego
Just a couple of data points - when the dots were disappearing yesterday while driving, the whole section was going out and then reappearing a few seconds later. They weren't going out one by one. Also I am pretty sure I have seen the green bar go all the way to the left. I am certain that right now I am not getting as much deceleration.

Hard to say with the provided information. Regen dots come back with continued regen. The more regen you do in a burst, the more dots you get, regardless of battery temperature. It is quite easy to get regen dots in a LR AWD Model 3, with outside temperature of 70+ degrees, in bright sunshine, after driving for over an hour, at 70-75% SoC, if you do a lot of regen. Obviously it is colder in your case so it is even more likely.

It may be unusual, but probably another few pictures, showing what you're seeing, with a capture of the outside temperature, and information about how long you've been driving, would be helpful. It was not clear on the exact conditions where you observed your behavior. You live in a potentially hilly location, and if you were heading down a decently long hill this behavior would be completely and totally normal. As you continue to head down the hill, at moderate states of charge, the car will reduce the amount of regen available, progressively.

If you store your car outside and you have an SR+ (EDIT: Looks like you do, based on your picture), this doesn't seem that unusual to me, either. It's even more likely in that case, since the weight of the car does not scale proportionally to the battery capacity (though you do have just one motor providing regen as compared to two in the AWD...but relative to an LR RWD you'll definitely be worse off).
 
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Jul 28, 2019
490
470
Brandon, Manitoba
I get the dots & message all the time until the charge level gets below ~60% or possibly lower. Never thought it was temperature related, and now that the temperatures here are below freezing, it has not seemed to change from when it was at 70f/21C. I still get the dots, but I do get limited regen after about 6km/4 mi. Typical charge level is 80%
 

Sophias_dad

Supporting Member
Supporting Member
Jul 29, 2018
1,543
1,620
Massachusetts
It definitely sounds like something is awry with OP's car. The regen limitation dots should only gradually come and go, not all appear/disappear.
 

AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
10,905
13,653
San Diego
The regen limitation dots should only gradually come and go, not all appear/disappear.

We need more information (the number of regen dots, how quickly they reappeared, exact conditions - temperature, how long had been driving for, what the grade of the road being driven was, how long the slope was, etc.). For sure, regen dots can come back, even after the battery has been nice and warmed up. The car does not like to regen too much for a significant period of time, even at a moderate (70%) state of charge. I think Tesla's just being conservative with the charging profile (and it's hard to correlate the limits with the Supercharger profile limits, since interpreting how many kW of regen there is at any time requires continuous CAN bus logging and/or correlation to the green line).

It is of course possible something is wrong; it's just hard to say with the information currently available.

It's also possible that with the next Supercharger update for the SR+/SR there may be changes to the amount of regen allowed, too. Depends on whether there are general limits placed on charging the battery which are very conservative right now.
 
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pjscott

Member
Apr 4, 2019
8
1
British Columbia
It may be unusual, but probably another few pictures, showing what you're seeing, with a capture of the outside temperature, and information about how long you've been driving, would be helpful. It was not clear on the exact conditions where you observed your behavior. You live in a potentially hilly location, and if you were heading down a decently long hill this behavior would be completely and totally normal. As you continue to head down the hill, at moderate states of charge, the car will reduce the amount of regen available, progressively.

If you store your car outside and you have an SR+ (EDIT: Looks like you do, based on your picture), this doesn't seem that unusual to me, either. .
It's not stored outside. Here's a picture after a few minutes driving after it had been garaged at 15 C for 12 hours. No hill that I traverse here is longer than 1/4 mile, the terrain is quite flat for the most part, and the dots are constant over all my drives which range up to an hour, except that once again, yesterday there was a period later in the day when all the dots disappeared for a few minutes. But otherwise I have been on a couple of dozen trips of 15-50 minutes each with no variation in this behavior since the s/w upgrade.

This temperature is not significantly different from the summer range (we are near the coast, there is little variation), and I would have expected a gradual change if that were the case, with only either a few dots appearing, and/or only for a short period, with at least some apparent correlation to the temperature.

Up until this point the only time I had ever seen any regen dots was after charging to > 95%.
 

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AlanSubie4Life

Efficiency Obsessed Member
Oct 22, 2018
10,905
13,653
San Diego
It's not stored outside. Here's a picture after a few minutes driving after it had been garaged at 15 C for 12 hours. No hill that I traverse here is longer than 1/4 mile, the terrain is quite flat for the most part, and the dots are constant over all my drives which range up to an hour, except that once again, yesterday there was a period later in the day when all the dots disappeared for a few minutes. But otherwise I have been on a couple of dozen trips of 15-50 minutes each with no variation in this behavior since the s/w upgrade.

This temperature is not significantly different from the summer range (we are near the coast, there is little variation), and I would have expected a gradual change if that were the case, with only either a few dots appearing, and/or only for a short period, with at least some apparent correlation to the temperature.

Up until this point the only time I had ever seen any regen dots was after charging to > 95%.

Seems like it is probably a software bug in that case...
 

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