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Manually warming the battery?

FurryOne

Member
May 1, 2019
138
120
Rome, NY USA
While you now have the option to set a departure time when you go to work so the battery will be warmed up, those of us who have finished the working part of our lives don't need that, but... What would be nice is to have a "PreWarm" option in the Tesla app that would allow us to use it any time of the day - say one hour before we wanted to go to the store. Also, it would need to be able to override the charging time set in the car, for those of us that set our cars to start charging at night when the rates are lower.
 

SigNC

Active Member
Aug 23, 2017
1,592
1,504
NC
you just have to go into the app and turn on climate. If the car or battery is cold it will warm it. the car up to whatever temp you set it to and I think the battery up to 50f/10c. likewise, it will draw power out of the up to what your ESVE provides or the max you have set to draw via the software setting.
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
12,553
15,012
Riverside Co. CA
While you now have the option to set a departure time when you go to work so the battery will be warmed up, those of us who have finished the working part of our lives don't need that, but... What would be nice is to have a "PreWarm" option in the Tesla app that would allow us to use it any time of the day - say one hour before we wanted to go to the store. Also, it would need to be able to override the charging time set in the car, for those of us that set our cars to start charging at night when the rates are lower.

Why would you need to pre warm your battery to "go to the store"? I know why you would want to pre warm the car (turn in the HVAC), but the reason you want to pre warm the battery would be to either accept a charge at optimal battery temps, or enable regen if the battery is cold.

If your model 3 is an "around town" car and you are not commuting to work, you would be wasting an hours worth of electricity to drive a few miles, just to enable stronger regen.

Maybe I am missing something, so what would be the reason you want to pre warm the battery, for going to the store or any other short trip?
 
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FurryOne

Member
May 1, 2019
138
120
Rome, NY USA
you just have to go into the app and turn on climate. If the car or battery is cold it will warm it. the car up to whatever temp you set it to and I think the battery up to 50f/10c. likewise, it will draw power out of the up to what your ESVE provides or the max you have set to draw via the software setting.

The question I have is if this will override the "charge time" settings, since I have my car set to charge at 1am. So if I turn on the climate setting, will it override the 1am setting and draw power from the HPWC?
 

FurryOne

Member
May 1, 2019
138
120
Rome, NY USA
Maybe I am missing something, so what would be the reason you want to pre warm the battery, for going to the store or any other short trip?

The "Store" I refer to isn't next door, but 15 miles away, and the weather here gets a bit chillier than SD.

Also, with my car set to charge at 1am (I have a dual rate meter) once the car fully charges I don't believe it will pull from the HPWC again until the next night, so warming up the car for any trip during the day would probably pull only from the battery despite being plugged in. (Unless someone can show me where the climate control overrides the charge timer.)
 
Last edited:

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Moderator
Nov 28, 2018
12,553
15,012
Riverside Co. CA
The "Store" I refer to isn't next door, but 15 miles away, and the weather here gets a bit chillier than SD.
Ok, that explains why you would want to warm the cabin (run the HVAC) but doesnt explain why you want to warm the battery?

To answer your other question, if connected to a wall connector. (tesla or otherwise) the car will pull power from the house to warm the cabin (which would also warm the battery).

I guess it depends on how you look at it, because it will use power from the home to warm the car, so yes its "charging" but its also not trying to replenish miles until your scheduled time, at least thats how I understand it.
 
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15 miles is roughly my commute to work. If I am traveling at a time where I know traffic will be minimal, I don't warm the battery. I do warm it if I know it will be a 40+ minute commute in traffic. My reason is the regen is all that is really lost with a cold battery. Without traffic and the need for regen, I don't see the benefit of using energy to warm the battery or the wear of the warming and cooling of the battery.
 

electrongeek

Metrology Fanboy
Nov 1, 2019
69
75
Maine
A warm(er) battery will deliver its power more efficiently, i.e. its internal resistance will be lower. At a given current draw, there will be less voltage drop to the motor and less power dissipated within the battery if internal resistance is lower. Also, regen will be more efficient. How much of a difference this would make in the overall scheme of things wrt total energy savings, I don't know.
 

rrolsbe

Member
Feb 18, 2017
312
199
Albuquerque
You can warm the traction battery without charging or running the HVAC if the battery temp is below 32F and the charge setting is above the current state of charge. You can verify this using the Smartphone App by monitoring that no miles are being added during the charging session. I am not sure there is any practical reason to do such a thing unless you live in an area where the temps stay below -20C/-4F for an extended period of time like 48 hours. This is the recommended lower long term storage temp for typical Lithium Ion batteries. The only other reason I can think of is if the car was exposed to temps of -22F or below for more that 24 hours, which might cause long term battery damage, and you did not want add any miles. Has anyone verified what Tesla does , if anything, when the car is exposed to temps below -22F or lower for more than 24 hours while plugged into shore power? not plugged in?
 
[QUOTE="rrolsbe, post: The only other reason I can think of is if the car was exposed to temps of -22F or below for more that 24 hours, which might cause long term battery damage, and you did not want add any miles. [/QUOTE]
I intend to expose my model 3 to extended cold well below -22F. By what mechanism is this damaging to lithium cells?
 

JulienW

Active Member
Jul 7, 2018
3,179
4,238
Atlanta
Sounds like a little (need to warm the) ICE left over mentality thread. No need to warm the battery before driving unless you need Performance driving. While regen and sometime full power may be limited the BMS has complete control and protects the battery.
 
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rrolsbe

Member
Feb 18, 2017
312
199
Albuquerque
[QUOTE="rrolsbe, post: The only other reason I can think of is if the car was exposed to temps of -22F or below for more that 24 hours, which might cause long term battery damage, and you did not want add any miles.
I intend to expose my model 3 to extended cold well below -22F. By what mechanism is this damaging to lithium cells?[/QUOTE]

Tesla states this in the owners manual but there is no mention of what exactly might be the issue. After reading further yesterday, I found no information indicating cell damage might occur. The only things that I am aware of that MIGHT be affected by very cold temps are glycol, washer fluid, 12V AGM battery, traction battery cells and differential oil. Traditional 12V wet cell lead acid batteries do not perform very well at temps of -22F and below, I would assume AGM batteries would be similar. There could be other issues with VERY cold temps but until Tesla weighs in with more specific information who knows. Maybe someone on this forum knows what the specific issue(s) might be?
 

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