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We had a massive heatwave here in SoCal today (105-115F) ambient temps most of the day, and it was interesting watching the Volt pull power from the wall to cool it's battery pack automatically:



This data is coming from my EVSE. The orange curve is instantaneous power (kW) and the black line is cumulative energy (kWh) drawn from the wall. Looks like the A/C cooling fired up roughly every 30 mins, and ran for a 8-minute session each. The power spikes to 2-2.3 kW and then levels to 1.3 kW for a bit before shutting off. I eyeballed the chart and it seems like each session pulled roughly 0.18 kWh, but this seems a bit on the low end.

Do ignore the massive 2nd and 3rd spikes-- those are from when I manually initiated remote cabin precondition sessions. I'm used to doing that for my non-active battery cooling EV (I won't mention which :p), so I did this out of habit. I stopped manually preconditioning once I saw this chart of it cooling itself automatically!

tl;dr: Volt's active battery TMS ftw! :D
 

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One question: will a Gen 2 do this even if not plugged in if there is enough battery charge? Our car was at the body shop for about three or four days in a row when the temperature was around 100° F, but the battery was 3/4 full, so I was wondering if it did that, although it was not plugged in, and was left outside at the time.

Thanks


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We had a massive heatwave here in SoCal today (105-115F) ambient temps most of the day, and it was interesting watching the Volt pull power from the wall to cool it's battery pack automatically:

... I stopped manually preconditioning once I saw this chart of it cooling itself automatically!
Also read this blog entry:

Title: Volt Battery Thermal Management System in the Hot Arizona Sun
https://gm-volt.com/2013/05/03/volt-battery-thermal-management-system-in-the-hot-arizona-sun/
 

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One question: will a Gen 2 do this even if not plugged in if there is enough battery charge? Our car was at the body shop for about three or four days in a row when the temperature was around 100° F, but the battery was 3/4 full, so I was wondering if it did that, although it was not plugged in, and was left outside at the time.

Thanks


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Good question. I have been told yes but only while over 60% charge. It would be nice to verify.
 

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The Volt cools the battery more aggressively when it is plugged in but still does so when it is not. I've seen mine do it down to about 1/3 charge...
 

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Interesting! I see that you purchased a 2018 Volt (congrats!). But my 2014 Volt does this automatic cooling off thing too, right? As long as it is plugged in, right? Thanks for sharing!
 

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Does anyone know the ambient temperature that causes cooling to take place? Will it cool itself while just sitting if the temp is over 90F? 100F?

My garage gets between 90 and 95F every day in the summer and I often unplug after the charge is complete due to thunderstorms. I've never noticed any kWH used when I first start it: it always says 0 kWH used. I guess that means it isn't actively cooling under those conditions.

Mike
 

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I do know that when our volts are parked in the driveway plugged in that the cooling system seems to operate sometimes as long as it’s been sunny most of the afternoon and the temperature is above 80 or so. I’m assuming that the car temperature is higher than the air temperature if it’s been baking in the sun for hours, so perhaps the car temperature is actually well over 100 at that point, even if the air temp is below 90.


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Does anyone know the ambient temperature that causes cooling to take place? Will it cool itself while just sitting if the temp is over 90F? 100F?

My garage gets between 90 and 95F every day in the summer and I often unplug after the charge is complete due to thunderstorms. I've never noticed any kWH used when I first start it: it always says 0 kWH used. I guess that means it isn't actively cooling under those conditions.

Mike
I don't have a way of directly getting a reading of the temperature of the battery pack but when I park in my garage the daytime temperature inside the garage can reach ~100F on a very warm day. If I drive my Volt in the early morning and return home by 9:30AM, if I don't plug in right away and wait until 3PM the Volt may switch on the fan and the AC as soon as I plug in the vehicle and it starts charging at a time when the garage temperature is at or near the highest temperature for the day. Other times if I plug in the Volt at 3PM to charge, when the Volt finishes charging the fan and AC may come on for ~10 minutes after charging has been completed. I have never experienced my Volt turning on the fan or the AC when it was not plugged in. The times when the Volt's battery is exposed to high temperatures, why an active battery temperature management with liquid cooling is so important, include while the battery is charging and when the Volt is being driven at high speed for prolonged periods (when the battery would be under a heavy load.)

In my experience the ambient temperature inside the garage needs to exceed 95F before the Volt will turn on the fan and AC to cool the battery. If the temperature of the battery pack goes above optimal for a short time it is not likely to cause any damage or measurable degradation, not any more than would be expected due to the age of the battery cells. Besides, what others have been experiencing in older, higher mileage Gen 1 Volts is not battery degradation (loss of EV range) but failure of one or more of the Volt's four battery modules. There is nothing to indicate that the failure of these older Volt batteries was caused by the Volt sitting, powered off in hot weather.

In an ICE vehicle, even with meticulous maintenance seals will age, leak fluids; cylinders may show lower cylinder pressure after 100k miles. I doubt that any ICE with 100k miles would be able to meet published performance specifications, as when new, without an engine rebuild.
 

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Does anyone know the ambient temperature that causes cooling to take place? Will it cool itself while just sitting if the temp is over 90F? 100F?
It's important to note that we are talking about the temperature of the battery pack here, not ambient temperature. The 400lb battery takes a while to heat up to ambient temps.

Reportedly the active TMS will run at 22°C / 72°F https://gm-volt.com/forum/showthrea...ent-system-temperature-band&p=45948#post45948

Other info indicates an 89°F upper limit instead: https://gm-volt.com/forum/showthrea...ent-system-temperature-band&p=48601#post48601

Some report no active TMS if the car is not plugged in regardless of the State Of Charge. Other's report active TMS while not plugged in or powered on as long as the SOC is at least 60% (some say 75%) full.
 

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The other day as I was working on one of my other cars, I happened to hear my 2013 turn on something. Don't know if it was a fan or a pump. It wasn't loud but lasted for maybe 15 minutes but can't be sure. It was in the shade (under lean to) with part of hood in the partial sun (lots of trees around), temp was 25C (mid seventies), fully charged, not plugged in. Any ideas if it was cooling the batteries or was it something else? I was a little surprised as it wasn't hot but it was muggy.
 

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The other day as I was working on one of my other cars, I happened to hear my 2013 turn on something. Don't know if it was a fan or a pump. It wasn't loud but lasted for maybe 15 minutes but can't be sure. It was in the shade (under lean to) with part of hood in the partial sun (lots of trees around), temp was 25C (mid seventies), fully charged, not plugged in. Any ideas if it was cooling the batteries or was it something else? I was a little surprised as it wasn't hot but it was muggy.
It might have been the pump for the fuel tank pressurization system.
 

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It might have been the pump for the fuel tank pressurization system.
Hadn't thought of that. It was coming from the front of the car. Is that where that pump is?
 

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Hadn't thought of that. It was coming from the front of the car. Is that where that pump is?
Gen 1 or 2? In the Gen 2 I believe the pump for pressurizing the fuel tank is located near the right rear quarter panel close to the fuel tank.

It could be a normal routine that is run to ensure that the air trapped in air space above the fuel in the fuel tank remains pressurized, significantly above the Reid vapor pressure of the fuel in the tank to minimize fuel vapors inside the fuel tank. It could indicate a slow leak such as a loose fuel cap but I think the fuel system would show an error code if there was a major air leak in the system.
 

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We had a massive heatwave here in SoCal today (105-115F) ambient temps most of the day, and it was interesting watching the Volt pull power from the wall to cool it's battery pack automatically:
Was your Volt parked in the blazing hot sun? Running every 30 minutes seems extreme, given what I thought was a well-insulated battery. From the analysis of the Volt battery management in the Arizona sun blog post, the Gen 1 battery was VERY well insulated and would take a long time to heat up. Running every 30 minutes or so seems a lot--unless the Gen 2 is not as well-insulated as the Gen 1. We all know they over-engineered the Gen 1.

You're sure this was TMS running and not some other reason for power draw?
 

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I thought that the battery disassembly video had demonstrated that the Gen 2 Volt's battery modules were not insulated or wrapped in thermal insulation. The reason it takes quite a few hours for the battery to heat up when parked is that the battery is a large mass of ~500 lbs and it takes a long time to heat up via thermal air conduction alone. The Volt's battery modules would heat up faster if the Volt is left baking in the sun.
 

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Be thankful you bought a Volt and not a Leaf.
 

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My 2014 ELR uses electricity when sitting in the Texas sun all morning. I hear the GE kicking on and off. It has quite a thwunk when it cycles on/off. Plus, it's bolted to the wall between the kitchen and garage, so, it amplifies the noise.
 

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And all this time I though the main battery was wrapped in WATER :)

and we still have the electronics cooling loop and the heat of the DC/DC charger ( front right ? )
 
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