[rmattila]

Does anybody know if the Volt is smart enough to stop heating the battery after being plugged for 48 hrs, or is there something wrong with my 2011? Wife charged it Monday evening and went for a trip till next Saturday. Tuesday was pretty chilly, -23 °C and the car drew 6 kWh in 24 hrs. Wednesday was warmer. At 0.00 the car drew a longer period, about 0.7 kWh, and today it has drawn nothing in spite of the -12 °C weather.

Would like to go check the car but I am an immobile quad...

 

[Steverino]

The car will thermal manage when plugged in. It may also thermal manage when when parked and not plugged depending on the car's State Of Charge.

Thermal management is not a dumb on/off light switch as your question seems to imply. Instead, it's more like a motion sensing light switch based on need (does the battery need conditioning?). If conditioning is needed, it will be applied until it's not needed.

If you want more details than that overview there is a longer explaining here: https://gm-volt.com/forum/showthrea...ent-system-temperature-band&p=45948#post45948

An very long discussion here: https://gm-volt.com/forum/showthread.php?5243-Volt-thermal-management-system-temperature-band

And a chart here: https://gm-volt.com/forum/showthrea...ent-system-temperature-band&p=48601#post48601

 

[rmattila]

All the discussions seem to suggest that the battery is kept at -4 °C whenever the car is plugged in. The last topping up of the battery took place 48 hrs after the main charging was completed. The ambient temperature had been around 0 °C for a few hours (since the previous top-up) so no heating would have been needed.

BUT THEN the ambient temp sank to -10 °C for twelve hours. From the links I find that it should have triggered the heating in any SOC.

 

[Barry]

I don't recall ever hearing anything about how long the TMS will keep going. It seems reasonable there is some point at which it would stop. Maybe you have discovered what that timeout period is.

Even if the battery gets cold soaked, there will be no damage and the car will still run when needed, although it will run on gas power for a while until the battery warms. When your wife returns, she can probably reset the TMS by momentarily starting the car or something like that. That way it will be more prepared for her next drive.

You might be able to trigger the TMS to run again yourself if you do a remote start. You can do that if you have access to the My Chevy smartphone app.

 

[rmattila]

I asked the nurse to check the led on the windshield. It was blinking normally.
Then she started the preconditioning. It took 60-70 watts for 4 hours and went back to zero. None of the usual 2300 W peaks.
Ambient temp was -5 °C. Normally it draws 30 W while the ICE is running. Now double that for 4 hours.

 

[rmattila]

Could not wait for my wife to return so I asked the nurse to start the car. -10 °C and the engine started ok. Gonna let it be on for half an hour before switching off and replugging.

They are forecasting -30 °C for the next night so I would rather not cold soak it.

 

[rmattila]

Yep, charging again normally. So, the TMS indeed appears to give up heating the battery after approximately 48 hrs. Smart design.

The charging station power intake from the past five days:

 

[rmattila]

Confirmation: starting the car did indeed cause the TMS to restart the warming up of the battery that it had given up after 48 hours. Seems to be a lot of cluelessness due to lack of proper documentation of the algorithm.