Cold weather charging

[Shelburne]

I charged my 2020M3 to 85% two days ago. Since then it has been sitting in my driveway, still plugged in. The temperature this morning at 7AM was 14 degrees F. I opened the app to see how much charge (if any) I had lost since the car reached 85% two days ago. I was happy to see it had only lost 3%, but I also saw that it was charging again and that there were three squiggly orange lines (like the signs for seat heaters being on, but orange) next to the SOC read out. I checked to confirm that the seat heaters, and the cabin heating are both off. I had never noticed this before during the past two years of ownership. So my questions are:
1. Do those squiggly lines indicate that the battery is being warmed, or what? There is no blue snowflake showing.
2. If the car looses SOC due to extreme cold, does it automatically begin recharging at some point, and how much SOC has to be lost before the car starts to recharge?

 

[srs5694]

I charged my 2020M3 to 85% two days ago. Since then it has been sitting in my driveway, still plugged in. The temperature this morning at 7AM was 14 degrees F. I opened the app to see how much charge (if any) I had lost since the car reached 85% two days ago. I was happy to see it had only lost 3%, but I also saw that it was charging again and that there were three squiggly orange lines (like the signs for seat heaters being on, but orange) next to the SOC read out. I checked to confirm that the seat heaters, and the cabin heating are both off. I had never noticed this before during the past two years of ownership. So my questions are:
1. Do those squiggly lines indicate that the battery is being warmed, or what? There is no blue snowflake showing.

I believe so.

2. If the car looses SOC due to extreme cold, does it automatically begin recharging at some point, and how much SOC has to be lost before the car starts to recharge?

Yes, if the SoC drops for any reason and the car is plugged in, it will charge automatically to restore your set SoC. I don't recall the exact loss amount before this kicks in, but I think it's somewhere in the 1% or 2% range. This value is, of course, subject to change with software updates from Tesla.

Given that charging in cold weather takes electricity to warm the battery in addition to the electricity that's actually fed into the battery, I prefer to do this less frequently in the cold than in warmer weather. (I have a driveway but no garage.) Thus, in the winter, I tend to charge the car and then unplug it; and I don't charge after every short drive (a trip to the supermarket, say). Instead, I charge every few drives, and preferably after a long drive, during which the battery will have heated up a lot. That minimizes electricity loss to heating the battery. That said, I wouldn't recommend over-doing this, since deeper discharges are bad for battery health. Also, if you charge just prior to departure, the heating of the battery for charging will improve the car's ability to do regenerative braking, which will save electricity. That will at least partially offset the power used to heat the battery, and might offset more than 100% of that. (I've never seen an analysis of this point.) Thus, if you have a regular schedule, you might use time-of-departure charging so that you get better regen when you drive.

 

[Shelburne]

I believe so.

Yes, if the SoC drops for any reason and the car is plugged in, it will charge automatically to restore your set SoC. I don't recall the exact loss amount before this kicks in, but I think it's somewhere in the 1% or 2% range. This value is, of course, subject to change with software updates from Tesla.

Given that charging in cold weather takes electricity to warm the battery in addition to the electricity that's actually fed into the battery, I prefer to do this less frequently in the cold than in warmer weather. (I have a driveway but no garage.) Thus, in the winter, I tend to charge the car and then unplug it; and I don't charge after every short drive (a trip to the supermarket, say). Instead, I charge every few drives, and preferably after a long drive, during which the battery will have heated up a lot. That minimizes electricity loss to heating the battery. That said, I wouldn't recommend over-doing this, since deeper discharges are bad for battery health. Also, if you charge just prior to departure, the heating of the battery for charging will improve the car's ability to do regenerative braking, which will save electricity. That will at least partially offset the power used to heat the battery, and might offset more than 100% of that. (I've never seen an analysis of this point.) Thus, if you have a regular schedule, you might use time-of-departure charging so that you get better regen when you drive.

Thanks. I'm retired and have no regular schedule. I usually charge the car when it's SOC gets down to between 25 & 35% or just before a long trip, and rarely if ever leave it plugged in long enough for it to lose enough SOC to initiate charging. When I charged it two days ago, it was in preparation for a r/t drive of about 180 miles, but then we decided to cancel that trip and I just left the car plugged in. This seems to explain why I've never noticed this before.

 

[jjrandorin]

Yeah those 3 squiggly lines ( People tend to call them "bacon" here on TMC) indicate battery heating. I am not sure cold the battery needs to be to trigger the actual icon. Kind of like the snowflake icon shows limited regen, but you can have limited regen without having the snowflake.

 

[blackT3$!@]

Do those squiggly lines indicate that the battery is being warmed, or what?

Tesla refers to them as "twisting lines". Your high voltage battery is maintaining its temperature for charging.

 

[andy.connor.e]

I charged my 2020M3 to 85% two days ago. Since then it has been sitting in my driveway, still plugged in. The temperature this morning at 7AM was 14 degrees F. I opened the app to see how much charge (if any) I had lost since the car reached 85% two days ago. I was happy to see it had only lost 3%, but I also saw that it was charging again and that there were three squiggly orange lines (like the signs for seat heaters being on, but orange) next to the SOC read out. I checked to confirm that the seat heaters, and the cabin heating are both off. I had never noticed this before during the past two years of ownership. So my questions are:
1. Do those squiggly lines indicate that the battery is being warmed, or what? There is no blue snowflake showing.
2. If the car looses SOC due to extreme cold, does it automatically begin recharging at some point, and how much SOC has to be lost before the car starts to recharge?

New feature to show if the car battery is heating. Car is plugged in charging and expending energy keeping the battery warm.

 

[Bikeman]

Do those squiggly lines indicate that the battery is being warmed, or what? There is no blue snowflake showing.

Sometimes referred to as the sizzling bacon strips. That's battery warming, and it will do that until the battery is warm enough to begin charging. If I remember correctly, it will do battery pre-conditioning first if under 40 degrees F. The blue snowflake is the next level down of coldness,

We're dealing with multiple days in a row here of sub zero degrees F. My plan is to keep it charged to 80% and plugged in for the duration. Sadly, I can't do that at work, so I will be driving the Prius for old-times sake. Continuous -10 F for long periods is not real good for the batteries. My Y is parked outside the house, and not in a garage. Brrrrrr.

 

[rpiotro]

Sometimes referred to as the sizzling bacon strips. That's battery warming, and it will do that until the battery is warm enough to begin charging...

Actually, it will begin charging immediately but at a highly reduced rate. The rate of charge will increase as the battery warms. You can follow this on the app if you would like to confirm it.

 

[afadeev]

Yeah those 3 squiggly lines ( People tend to call them "bacon" here on TMC) indicate battery heating. I am not sure cold the battery needs to be to trigger the actual icon. Kind of like the snowflake icon shows limited regen, but you can have limited regen without having the snowflake.

From the manual:

You may also live to see the following two warning modes:

Continuous -10 F for long periods is not real good for the batteries. My Y is parked outside the house, and not in a garage. Brrrrrr.

If you can help it, consider moving EVs into a heated (or at least insulated) garage during the winter.
Park ICE vehicles outside.
There is zero downside to ICE drivetrain from freezing temps, while the batteries are very temperature sensitive. Not to mention the Model 3/Y door handles that have a tendency to freeze shut, and frame-less door windows that get stuck to the rubber gaskets.

BTDT.

HTH,
a