I have had my model 3 since March of last year. I live at 7000’ in Colorado and have started having issues with regenerative braking. It works leas than half the time. I spoke to the dealership and they simply said its functioning varies based on temperature. I asked at what temperature that it begins to drop off. She basically had zero answer for me. Does anyone have any actual technical information on this? Otherwise, how do I know if there is a malfunction with the regenerative braking. Thanks
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Regen issue?
- Thread starter Jdenfield
- Start date
It's less about air temperature and more about the temperature of the battery. When the battery is cold it will regen less. Once it warms up it can handle more. When it's really cold though you'll never get full regen unless you drive for quite some time.
I set the car to blend in friction brakes when the regen is too low. Lets me keep the one pedal driving.
Preconditioning will help since it will warm the battery up but I don't find it really necessary with the blend option enabled.
I set the car to blend in friction brakes when the regen is too low. Lets me keep the one pedal driving.
Preconditioning will help since it will warm the battery up but I don't find it really necessary with the blend option enabled.
Second @Braumin's comment. Under current software there's an icon that appears on the left side of the screen that indicates that there's a cold battery; so long as that's there, regen is reduced or eliminated.
I haven't checked recently, but for quite a time the little gas_it/regen_it bar that's below the speed limit icons would put up a grey or dotted line on the left, regen, side; the grey/dotted line would initially start on the left and go towards the center; the right end would shrink towards the left as the battery warmed up.
Finally: 2021 M3's do have a heat exchanger. Unlike, say, my 2018 M3. The heat exchanger is designed to warm up the battery quicker than with the older models. It's... just... possible that if the exchanger isn't working right, or is stuck or something, you could get issues where the car didn't warm up properly. And that includes regen. I frankly got no clue if this is even possible without warning messages all over. But check the W-h/mile plot on the Energy display. In cold weather, one would expect anywhere from 400 to 350 W-hr/mile initially, dropping down to 280 or so W-hr/mile once the car gets warmed up, usually within a half-hour or less. If it's stuck at the higher numbers.. there might be a problem.
I haven't checked recently, but for quite a time the little gas_it/regen_it bar that's below the speed limit icons would put up a grey or dotted line on the left, regen, side; the grey/dotted line would initially start on the left and go towards the center; the right end would shrink towards the left as the battery warmed up.
Finally: 2021 M3's do have a heat exchanger. Unlike, say, my 2018 M3. The heat exchanger is designed to warm up the battery quicker than with the older models. It's... just... possible that if the exchanger isn't working right, or is stuck or something, you could get issues where the car didn't warm up properly. And that includes regen. I frankly got no clue if this is even possible without warning messages all over. But check the W-h/mile plot on the Energy display. In cold weather, one would expect anywhere from 400 to 350 W-hr/mile initially, dropping down to 280 or so W-hr/mile once the car gets warmed up, usually within a half-hour or less. If it's stuck at the higher numbers.. there might be a problem.
Like @Braumin said, try preconditioning, that'll help. Also for max regen, keep battery level below 70% (unless you're going on a trip). Regen will also be reduced if the car sense a loss of traction on slippery surfaces, or if you're going down very long slopes non stop.
If it's a "new" problem to you, then it's most probably related to battery temperature.
Unfortunately I don't think I've seen any "actual technical" info about it directly from Tesla.
It would be very very (VERY VERY) difficult to try to identify any issue with regen braking, because the car includes a computer (the battery management system or BMS) which has the task of managing the battery. Part of that management is deciding how much energy can be put back into the battery (regen), because the amount of power generated by regen can be like DC fast charging.
There are various things that impact regen, the amount of regen etc. You just got your car in March of last year, which means you havent had a winter season with the car yet. Battery temperature is one of the many things that impacts the amount of power the BMS will let the battery take at any one time, and it doesnt have to be a snowflake icon or limited regen dots for the car to still want to prevent some regen.
If you really wanted to dig into this (for your own personal information, not because you are going to get some information that you will be able to take to Tesla and say "See, regen isnt right!", you can setup something like scanmytesla, but I dont recommend it unless you are already a data geek type person and know that none of the information you get from it will be able to be taken to tesla for basically anything.
I dont use it, but it can show you battery temperature, as well as lots of other stuff.
If your basic question is "Is there something wrong with regen in my car", I could confidently say "no, especially because you havent lived through a winter with it to know how it reacts in the cold, and you live at altitude".
If you are driving down (and then back up) mountains all the time, and perhaps want more regen, charge your car to a lower percentage when you are at the top of the mountain. Even with that, you will still have less regen when the car battery is cold, and air temperature doesnt necessarily correlate to how cold the battery might or might not be at that time.
Gauss Guzzler
Safety Score = 42
There are no hard numbers. The amount of regen available depends on the combination of temperature, state of charge, and amount of regen recently used.
Turn on the option to "use brakes when regen is limited" and you'll hardly even notice.
Turn on the option to "use brakes when regen is limited" and you'll hardly even notice.
I'm not a big fan of this. That just puts a lot more wear on your brakes just to feel like your regen braking. I'd rather coast which would save my brakes and also be more energy efficient since you're not losing the energy you used.
Noted: I'm not saying you're wrong or that is a dumb idea. If it works for you then that's ok. I'm just stating my opinion which is neither wrong nor right.
BitJam
Active Member
The car will tell you if the battery is too cold for full regen:
Tesla cold weather and winter driving tips
Tesla cold weather and winter driving tips, including range, regen, preconditioning , tyre pressures and safety on autopilot
tesla-info.com
A cold battery will be most easily recognised by a dotted line on the power meter below zero. The dotted part of the line indicating that area is not accessible.
The power meter is a horizontal bar about 1/4 or 1/5 from the top of the touch screen. It will normally show you regen (green to the left of center) and power usage (green to the right of center).There is also a snowflake icon that tells you the battery is too cold for full power and full regen:
Winter Driving Tips | Tesla Support Other Europe
Your Tesla vehicle has several features designed specifically for cold temperatures. Learn how you can enhance your cold weather driving experience by following tips such as staying plugged in and preconditioning your battery before each trip.
Watch for the Snowflake Icon
A blue snowflake icon may appear on your touchscreen and in the app if your battery is too cold for full power and ideal range. When this icon is displayed, you may notice reduced regenerative braking and acceleration.
If you are losing regen and there is no indication via dots on the power bar or a snowflake icon then maybe there is a malfunction but, as others have said, this seems unlikely.
BitJam
Active Member
I am a big fan of blending friction brakes with regen when regen is limited. For me, I almost only lose regen first thing when I leave my house and go down a big hill. If I'm not paying attention to all the indicators (see above) then not having regen can be a big and unwelcome surprise. You can still mostly coast if you want by using a light touch on the accelerator.
It's great that that can be turned on or off to suit different people. Same thing with the new auto off blinkers. Where I drive they are more of a hindrance than a help so I just turn them off.
Shelburne
Member
On very cold mornings, it has taken as much as 18 miles for my car's battery to warm up enough so that the car has full regeneration when I don't pre-condition it. As others have said, just keep it plugged in on cold mornings and, using the app, schedule your departure time so the battery is pre-conditioned and the cabin is cozy.
Your car is also equipped with the heat pump. Meaning when the cabin heater is turned on, it will scavenge heat from the drivetrain/battery pack. This has the net effect of heating the cabin more efficiently at the expense of warming up the batteries with waste heat.
Blending the friction brakes via the software toggle will give you a more consistent one pedal experience.
Blending the friction brakes via the software toggle will give you a more consistent one pedal experience.
Holy Cow!
You all are good and fast. A little background and some answers to questions and comments.
March in Colorado at 7000’ is winter and plenty cold. So while it may not be as cold as December/January it is still well below freezing at night. The Regen appeared to engage more consistently then.
Most of my drives tend to be short so the battery likely would not have much time to warm up. That said, it is in an insulated garage and never gets below 40 degrees.
I typically charge to 85% and don’t recharge till I am down around 30%.
My drive into town is down 1700’ and I am acutely aware of needing to brake when the Regen isn’t engaged.
Last night I went to a party for a few hours. The car was at 42% when I left my house. When I left the party at 11 pm it was 26 degrees F. The green regen circle wasn’t on and regen functioned fine.
My entire problem with this is that there doesn’t seem to be any consistency as to why regen is engaging or not. I track the temperature of the air, not the battery, all the time. There certainly has to be a relationship between the two and the regens function is supposed to be related to temperature. It doesn’t appear that the temperature is the factor that determines if the regen is engaging. Although I’m sure I could be wrong.
Most importantly, you are a great group of engaged and enthusiastic individuals and I appreciate your thoughtful and civilized responses to my dilemma. A happy and healthy new year to you all.
Josh
You all are good and fast. A little background and some answers to questions and comments.
March in Colorado at 7000’ is winter and plenty cold. So while it may not be as cold as December/January it is still well below freezing at night. The Regen appeared to engage more consistently then.
Most of my drives tend to be short so the battery likely would not have much time to warm up. That said, it is in an insulated garage and never gets below 40 degrees.
I typically charge to 85% and don’t recharge till I am down around 30%.
My drive into town is down 1700’ and I am acutely aware of needing to brake when the Regen isn’t engaged.
Last night I went to a party for a few hours. The car was at 42% when I left my house. When I left the party at 11 pm it was 26 degrees F. The green regen circle wasn’t on and regen functioned fine.
My entire problem with this is that there doesn’t seem to be any consistency as to why regen is engaging or not. I track the temperature of the air, not the battery, all the time. There certainly has to be a relationship between the two and the regens function is supposed to be related to temperature. It doesn’t appear that the temperature is the factor that determines if the regen is engaging. Although I’m sure I could be wrong.
Most importantly, you are a great group of engaged and enthusiastic individuals and I appreciate your thoughtful and civilized responses to my dilemma. A happy and healthy new year to you all.
Josh
My thinking: It's you vs. the Battery Management System, which is the bit of hardware/software that tells the rest of the car whether regen is going to happen or not. Dunno if you've uncovered a bug or not.
I have a suggestion, though:
- Tesla are the people who state that, "A plugged-in Tesla is a Happy Tesla." There's lots of people who disagree with this approach.. but that is the auto manufacturer itself saying these things. So.. Set the limit to 70% or 80% and leave the car plugged in for what follows.
- As one of the previous posters mentioned, one can do a pre-heat of the car with a "scheduled departure" setup. Done that myself during the winter months; one gets better mileage because it's not just the cabin that gets warmed up, it's the battery, too. It doesn't take all that long for the pre-heat to finish once started, either: An hour, tops, and more likely 30 minutes. So, leave the car plugged in. And, when you know you're going to be leaving in, say, an hour or so, use the app on the phone to set up for scheduled departure. Do this a number of times and see if your regen issues disappear.
As far as getting moving at 26F: Well, one can set the car to warm up, scheduled or not, and that also tends to warm the battery.
Make the experiment, then report back? Inquiring minds would like to know.
Finally: There is such a thing as a "Bug Report". There's been a variety of explanations on this forum about what that actually does, but, well, that's us talking, not Tesla. But, after running the experiment, hit the right scroll wheel when regen doesn't kick in as expected, and state, "Bug report, regen not working." Keep on doing that. Might make a difference.
As to relationship between air temp and battery temp, I don't have enough detail to know if the following applies to your case, but thinking as an engineer there is thermal inertia.
I'm not a mechanical engineer, but that said:
How long has it been sitting at the temp, how warm was it before exposed to that temp?
The mass of the battery pack, which differs by model and battery chemistry would also play into this.
I would expect a wind-chill factor to apply to the battery as well as people. If the air is still with a temp delta between air and battery, heat is exchanged so the colder air will warm some as the battery cools. If the air is flowing, like a fan over a motherboard, the warmed air is constantly replaced with colder air speeding the transfer.
Also, not sure, but I would expect the heat transfer coefficient would differ by medium, meaning if the outside of the battery pack case was physically touching something including water/snow, or there was higher humidity in the air, those might effect how quickly it cooled. If the water on the case contained road salt, that would also impact the heat transfer coefficient.
I'm not a mechanical engineer, but that said:
How long has it been sitting at the temp, how warm was it before exposed to that temp?
The mass of the battery pack, which differs by model and battery chemistry would also play into this.
I would expect a wind-chill factor to apply to the battery as well as people. If the air is still with a temp delta between air and battery, heat is exchanged so the colder air will warm some as the battery cools. If the air is flowing, like a fan over a motherboard, the warmed air is constantly replaced with colder air speeding the transfer.
Also, not sure, but I would expect the heat transfer coefficient would differ by medium, meaning if the outside of the battery pack case was physically touching something including water/snow, or there was higher humidity in the air, those might effect how quickly it cooled. If the water on the case contained road salt, that would also impact the heat transfer coefficient.
I believe it's been confirmed that the bug report function will record data in the car, but a tech would have to read it. It's not automatically sent to Tesla.
I have had the same problem twice lately (LR Dec 21).
The first time the car had been parked at our mountain cabin in relatively cold weather (-10C) for 2 days, but my previous 2019 LR never had this problem even in colder weather. It was quite scary driving down the mountain with absolutely no regen. The autopilot also did not apply the mechanical brakes. No warning message shown.
The second time it was -2C, and I was parked for only 2 hours.
I got a warning that the regen was not working, and that if the problem persisted I should book a service. It was extremely slippery due to rain on cold ice, so I stopped the car and shut it down in the Service menu. After starting up again the problem was gone. Strangely the warning message does not show up in the app.
I am having a problem with regen braking being limited on my 2018 M3. I charge the car to 80% nightly. Temperatures here are in the 40s in the morning, but warm to mid 60's during the day. This has been going on for over 6 weeks. If regen braking returns to normal, it is limited again after another nightly charge to 80%. Local Service Center is telling me this is due to temperature and is 'normal' - but my vehicle has never experienced limited braking like this in these kinds of temperatures in the last 5 years. Anyone else experiencing this and/or have advice how to escalate this since my Service Center doesn't have a solution?
There is no way to escalate it. Tesla changed the algorithms for regen braking (probably because regen braking is similar to supercharging with the amount of energy put in the battery), so regen is less strong than it was before, and it appears its more sensitive to temperature.
There is no one who is going to change this for you, and no way to escalate it. Change your brake options to use the regular brakes when regen is limited, that is the only option you have.
I know many Tesla owners in my area an no one else is experiencing regen braking issues. Why would this affect my vehicle and not others in my area under the same kind of temperature conditions?
Unless you have driven their cars, parked in the same place yours is, for the same amount of time, you cant say its the same conditions. They also might not consider lesser regen an issue, especially since you can now choose to have the car add the brakes when there is less regen. Have you tried that? Going to tesla is going to be a non starter but you are welcome to try that avenue. You just wont get anywhere with it, as you have found, and there will be no escalation path for it because they will tell you what they already told you.
This is not much different from owners talking about "my car doesnt get rated range". I realize its not the same topic, but there is nothing for them to do for you for it.
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