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Discussion Starter · #1 ·
Are there any technical descriptions that explain when the BOLT does thermal management of the HV battery for cold and hot weather, when plugged into L2, and not plugged into L2 (when the car is parked)?
 

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manual states it should be plugged in if experiencing extreme temperatures. conditioning appears from observation to be different when unplugged but have yet to see any official published criteria when unplugged. other than long term storage and shipping, there's no criteria published when unplugged. Some have observed energy usage when left unplugged. Speculation seems to indicate that the battery has to be above 40 percent state of charge in order for the car to condition unplugged. Technical data would be nice. Does it check in so many hours or does it trigger at some setpoint? Many have tried to determine it but not successful that I'm aware of. Lot's of data plugged in as people can monitor the EVSE current draw.
 

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There was a contributor here that did rather extensive 'testing' - there's a thread somewhere (prob in battery portion).
 

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This is raitchison's favorite topic.
Not too far off actually ;)

In any case read through the topics linked but here is a summary of my observations.

When the car is not plugged in and not turned on I have not observed any battery conditioning with the battery temps reaching as high as 37C/99F

When the car is not plugged in but turned on and the battery temp is above ~33C the car will cool the battery to 31C

When the car is plugged in and charging I have not witnessed any battery conditioning but I have never attempted to charge the battery when it is hotter than 27C

When the car is plugged in and NOT charging (either charge complete or charge not needed) the car will cool the battery to 27C and repeat the cooling cycle periodically to maintain 27C

You can force/trick the car into cooling the battery while charging by leaving the car turned on while you are charging.

There's a LOT more to it than that but that's as succinct as I can put it.
 

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Wasn't there also something about running the A/C (Air Conditioning) helping to keep the battery pack cooler?
 

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Wasn't there also something about running the A/C (Air Conditioning) helping to keep the battery pack cooler?
Sort of, but that's getting a bit into the details so I did not include it above.

Basically if you have the cabin AC on during the battery cooling cycle the battery coolant will be chilled to a colder temperature (IIRC about 10C colder) which should in theory cause the battery to reach the target temperature (31C or 27C depending on the mode) faster.

Also if you do not have the cabin AC on during battery cooling the car will cycle the AC compressor on and off several times per minute, but with cabin AC on the compressor runs continuously. I don't know about the electrically driven AC compressor in the Bolt but in a traditional engine driven AC compressor you will wear out your compressor and especially the compressor clutch (which engages and disengages the compressor from the drive belt) cycling it like that.

For both reasons above I always turn on cabin AC when I'm cooling the battery. I usually set the fan speed to the lowest setting to draw the least amount of power (unless I want more cooling for my own comfort) and I usually just turn on the floor registers.
 

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When the car is not plugged in and not turned on I have not observed any battery conditioning with the battery temps reaching as high as 37C/99F
I can't say why, as I was not monitoring my Bolt, but I have on multiple occasions during the summer had my car perform battery conditioning while unplugged and it was hot. Since I was not monitoring I don't know what the temperature of the battery was, outside it was high 90s and sunny with my car sitting in an open parking lot. I've been outside near my car when it has done it, funny hearing your car come to life on its own without you telling it to.
 

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Any details in terms of warming the battery pack during the cold?

No I have not done any cold weather testing and probably won't have the opportunity to as it never gets very cold here (coldest temps we ever see are in the high 20s and that's only for a couple hours in the early morning a handful of days a year.)

I can't say why, as I was not monitoring my Bolt, but I have on multiple occasions during the summer had my car perform battery conditioning while unplugged and it was hot. Since I was not monitoring I don't know what the temperature of the battery was, outside it was high 90s and sunny with my car sitting in an open parking lot. I've been outside near my car when it has done it, funny hearing your car come to life on its own without you telling it to.
Interesting, now I'm not logging with torque when the car is parked and even if I tried to the OBD port shuts down after some period of time (not sure how long) so it would likely be impossible to monitor the car 24/7 but I have not witnessed any evidence of the car initiating battery cooling when turned off and not turned on including with ambient temps over 110F and battery temps as high as 37C.

What year is your Bolt?
Have you had the BMS recall done?
 

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Interesting, now I'm not logging with torque when the car is parked and even if I tried to the OBD port shuts down after some period of time (not sure how long) so it would likely be impossible to monitor the car 24/7 but I have not witnessed any evidence of the car initiating battery cooling when turned off and not turned on including with ambient temps over 110F and battery temps as high as 37C.

What year is your Bolt?
Have you had the BMS recall done?
2017, Manufacture date is sometime in december 2016. I have not had the BMS recall done yet.
 

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Discussion Starter · #13 · (Edited)
We go to -30F, or at least the mid -20s recent years for a day to a few days here and there (mostly in the early morning hours before sunrise, sometimes through the morning) in Dec/Jan with an unheated, but attached garage. I might be able to get some insight into cold wx, HV battery warming from the chargepoint graphs alone. Many thanks for info on warm wx cooling and past threads, I have a lot to read and learn. -Joe
 
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