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Regen brake loss

D.Jeon

Member
May 13, 2020
13
1
Toronto
Hey guys,

so I have I 2020 model 3 SR+. I recently noticed that my regen braking only has about 70% power, I did have dots on the bar which have recently disappeared but still only get 70% regen. I contacted Tesla who advised me that because I charge to 90% consistently and my charging range is from 50%-90% it would affect the regen. I was advised to drain the battery to atleast 20% and charge to 90% for a week or two to recalibrate the regen. Also would that mean that I would have to calibrate the regen every so often? I was first told that once my battery reaches below 90% that i should get full regen but was then told I needed to recalibrate?? any knowledge would be appreciated, thanks.
 
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roblab

Active Member
Jul 15, 2008
3,550
2,608
Angwin (Napa Valley) CA
Not so much knowledge, but some experience. Regen takes kinetic energy and runs it through the gears to the generator, to push it into the battery. If your battery is near full, or thinks it's near full, the car will not allow energy to be pushed into the battery, which would harm the battery. Also, if your battery is hot or unduly cold, the car will try to protect the battery first, and cut regen.

I'm not sure what they mean by having you recalibrate, but I would guess by what you tell that it would be a one time job. And often you don't get full regen below 90%. It depends on a lot of factors. Mainly, I find that the battery has to be well less than 90% to get full regen. You're cramming electrons into a battery, so being almost full will definitely slow that process, as will a hot battery.

If you're worried about regen, keep your battery nearly empty (!) so it has lots of room to accept those electrons. Or not. If you know your battery is full-ish, don't go trying to cram energy into it. Just expect that regen will be reduced.
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,490
10,677
Riverside Co. CA
You will not have full regen anytime you have dots showing. That shows that your battery can not take full regen, usually because its too cold to (the battery). To preemtively answer the usual next question, yes the battery can be cold even if its 70 degrees outside, or even 70 degrees in your fully enclosed garage.

Never heard of calibrating regen, they were giving you the standard answer about the battery, probably because they answer 200 questions a day that start with "I dont understand why My car only charges to XXXX" or "I dont understand why I drove 100 miles buy the car lost 140 miles".
 
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sroy

Closed
Mar 13, 2021
542
225
New Jersey
My understanding is that to maximize battery life you should keep the battery between 50-80/90% but if your driving habits are such that you rarely go below 20-60%, while battery lofe is better overall, the software “knows” less the battery so it’s accuracy is lower. The comprise is to go one week out of every month or every other month without charging. Not sure if that’s related to regen or not.
 
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jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,490
10,677
Riverside Co. CA
My understanding is that to maximize battery life you should keep the battery between 50-80/90% but if your driving habits are such that you rarely go below 20-60%, while battery lofe is better overall, the software “knows” less the battery so it’s accuracy is lower. The comprise is to go one week out of every month or every other month without charging. Not sure if that’s related to regen or not.

Thats a nice summary of about 150 pages of battery threads ;). AFAIK, regen is really only impacted by the batteries ability to take a charge, either because "its too cold (the battery), or "its too full".
 

D.Jeon

Member
May 13, 2020
13
1
Toronto
Not so much knowledge, but some experience. Regen takes kinetic energy and runs it through the gears to the generator, to push it into the battery. If your battery is near full, or thinks it's near full, the car will not allow energy to be pushed into the battery, which would harm the battery. Also, if your battery is hot or unduly cold, the car will try to protect the battery first, and cut regen.

I'm not sure what they mean by having you recalibrate, but I would guess by what you tell that it would be a one time job. And often you don't get full regen below 90%. It depends on a lot of factors. Mainly, I find that the battery has to be well less than 90% to get full regen. You're cramming electrons into a battery, so being almost full will definitely slow that process, as will a hot battery.

If you're worried about regen, keep your battery nearly empty (!) so it has lots of room to accept those electrons. Or not. If you know your battery is full-ish, don't go trying to cram energy into it. Just expect that regen will be reduced.
thank you. Even at 60% below I don't get full regenbut i will try to "recalibrate"
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
9,490
10,677
Riverside Co. CA
thank you. Even at 60% below I don't get full regenbut i will try to "recalibrate"

There is no "calibration" needed for regen. You wont get full regen if your battery is cold, no matter what percentage charge you are at, and your battery will be cold when you first get into it pretty much no matter what the temperature is, unless it JUST finished charging.

All the calibration stuff is for battery capacity, not regen.
 
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Gauss Guzzler

Member
Dec 27, 2020
275
312
Thousand Oaks, California
All the calibration stuff is for range estimation, it has no effect on the battery or the car's behavior in any way. It's just a way of improving the accuracy of the range estimate icon on the screen.

The battery needs no care but as the car will notify you, it's preferable to stay in the 20-80% SOC range if convenient. And as others have noted, a cold full battery will have reduced regen ability.
 

iaflyer

Member
Sep 21, 2017
107
112
Ann Arbor, MI
Also, what you think is "not cold" for Toronto is still cold for the car and battery. I live in Michigan, so anytime this month (May) the car has been below 65 degrees F overnight I still get .... showing on the Power meter at 90%. Once I've driven some, used some battery and the battery pack warmed up, the regen kicks in to maximum.
 
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