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Discussion Starter #1
Apologies in advance if this has been covered, but I have tried searching and was unable to find an answer to this specific question:

Is the temperature management system on the battery active if the car is plugged in but not actively charging (i.e. in delayed charging mode)?

I've found several references to the fact that the TMS is only active when the car is plugged in, but they didn't specify whether or not the car had to be actively charging in order for TMS to kick in.

I am particularly concerned because I turned in my 2013 Leaf a couple months ago, and the battery had degraded to such an extent that I was getting about 1/3 less miles per charge than when new. I'm pretty sure this was primarily due to heat. I want to make sure I do everything I can to protect the Volt's battery, as I have purchased this car not leased it. Thanks in advance for your collective help.
 

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Yes, the TMS can operate even when the car is off and not plugged in...
 

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Discussion Starter #3
Yes, the TMS can operate even when the car is off and not plugged in...
Interesting - that is contrary to what I have read elsewhere in the forum. Everything else I've read seems to indicate that the car has to either be on or plugged in for TMS to operate. I just wasn't sure if it also had to be actively charging if plugged in.
 

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Here's a good reference describing the behavior of the TMS for the Gen 1 Volt. I haven't seen anything about the Gen 2 to indicate it's the same or different. Results suggest that, except under extreme conditions, the TMS will remain off if the car is off and unplugged. But, the battery is so well insulated, it takes a long time to warm up. As soon as the car is turned on the TMS will kick in.

I recall seeing a lot of recommendations to leave the car plugged in when not in use. Even when it's not charging, the TMS will work when the car is plugged in.

http://gm-volt.com/2013/05/03/volt-battery-thermal-management-system-in-the-hot-arizona-sun/


I'll add that I had a 2012 LEAF that lost about 25% of its battery capacity during a three-year lease. My 2013 Volt, which was also on a three-year lease, had the same 40-mile electric range the day I turned it in as the day the dealer delivered it to me on day one. I feel so confident in how well the Volt manages its battery that I bought my 2017.
 

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I believe the TMS will activate in extreme heat even if not plugged in, to cool the battery, but only if the charge level is above 50%.
 

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I have not heard that it has changed for 16+

When the vehicle is running (in the ON position or remote started) - it will always heat or cool the battery to maintain optimum temp.

When hot outside:
Fan and/or AC can start whenever required, regardless of plug state
The requirement is also conditional on state of charge. If the battery is low on charge, it does not have as great a need for cooling. It's when it's full that it will need to self-cool. Standby unattended AC does not run below half charge or so. Though perhaps might still in extreme temps.

When cold outside:
Battery heater will activate by itself only when plugged in (even when not actively charging - e.g. you charged the evening before and it is below freezing at 3am, it will cycle battery heat as needed)
When unplugged battery heat will not activate. Though I think it should at least maintain bare minimum for EV operation - e.g. if I have 95% battery there is plenty of energy to keep it at -9C for hours, perhaps days before running out
Freezing is not critical to the battery, so I guess they figured not worth starting up the heater for this.
In a fail-safe mode, if battery temp drops to -10C or lower it will activate under engine propulsion until the battery has warmed up, instead of using standby heater to maintain the minimum, as I mentioned above would be a nice thing to have.
BEVs do not have this fail safe luxury and must use standby heater to keep battery above minimum temp.
 

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As for the battery, I wouldn't worry at all about treating your volt any differently. The battery is babied, doesn't charge all the way up or drain all the way down to avoid any battery degradation issues. During the summers, my car actually warms my garage while charging, so it is a bit annoying, but you live with it because it's all done in the name of battery preservation.

The volt design is vastly superior to the leaf. Welcome from the dark side to the light side.
 

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When unplugged battery heat will not activate. Though I think it should at least maintain bare minimum for EV operation - e.g. if I have 95% battery there is plenty of energy to keep it at -9C for hours, perhaps days before running out.
+1.

I would love to hear an explanation from GM for why they don't do anything to prevent the Volt from potentially becoming disabled in extreme cold temperatures via a frozen battery, especially when the solution seems simple and risk-free.
 

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I think, if it is too cold, you will get a message telling you to wait, until the electric heater has warmed the battery enough to operate.
 

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+1.

I would love to hear an explanation from GM for why they don't do anything to prevent the Volt from potentially becoming disabled in extreme cold temperatures via a frozen battery, especially when the solution seems simple and risk-free.
They do. You just plug it in. If you are at a spot where there is no place to plug in and it is cold enough to freeze the battery, no other cars will be starting either.
 

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+1.

I would love to hear an explanation from GM for why they don't do anything to prevent the Volt from potentially becoming disabled in extreme cold temperatures via a frozen battery, especially when the solution seems simple and risk-free.
It is a bit poitless, the range is short anyway that it leeches away any you might have. Tesla has to do this, and results in a dead battery at the airport if you aren't careful. Or more likely maybe not enough range to make it home. I imagine Bolt EV will have to do this too.

Volt can still start and run on gas unless it is cold soaked below -20F or something, although deep cold ERDTT is annoying. Effectively making it a gas car.

I think the heaters run at low power when the car is running, but not sure. I notice a huge range /efficiency hit for the first few miles while cold, but if the battery is warmer or I drive more than a few miles efficiency seems to jump up. I lost my ELM OBD2 scanner so I can't check battery temp.
 

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I think, if it is too cold, you will get a message telling you to wait, until the electric heater has warmed the battery enough to operate.
Nope. If it's too cold, the electrolyte freezes and the car won't start unless/until you plug it in and allow it to use grid energy to warm the battery.

If you are at a spot where there is no place to plug in and it is cold enough to freeze the battery, no other cars will be starting either.
Except no ICE car has a large battery pack with enough stored energy to easily keep the internal pack temperature above the point at which the electrolyte freezes for an extended period of time. (Assuming the HV battery isn't already drained.) So why not use this unique capability to be BETTER than an ICE car for starting in extreme cold?

It is a bit poi[n]tless, the range is short anyway that it leeches away any you might have. Tesla has to do this, and results in a dead battery at the airport if you aren't careful. Or more likely maybe not enough range to make it home. I imagine Bolt EV will have to do this too.

Volt can still start and run on gas unless it is cold soaked below -20F or something
Exactly. unless it is cold soaked below -20F. So why not ensure that the car will start even when it is cold soaked below -20F? I know it's very unlikely to happen to 99.99% of Volt owners. But it might not seem so pointless the one time it actually happens and somebody gets stranded.

And the comparisons to BEV's are not particularly helpful. Losing X miles of range in a BEV might prevent you from reaching your next destination. But in a Volt, you still have the engine to get you where you need, even if the battery loses X miles of range.
 

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I didn't notice one while I was under the car, but I'm assuming the Volt doesn't have a 12v engine starter(?) Perhaps the system allows use of the traction battery to start the ICE (via motor or motor/generator), but not for further propulsion electrically if it gets cold enough.

I wish I could give the OP more info, but it doesn't get cold here and I have yet to leave the car unattended at the long term airport parking lot. No observations yet..
 

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Discussion Starter #14
Thanks for the replies. My main concern was regarding heat, as it doesn't get cold her in Southern California. The info in this thread seems to indicate that the TMS will kick in to cool the battery if it is unplugged and not on if the conditions are hot enough, and if there is enough charge in the battery to warrant the protection. Additionally, it seems that the TMS operates while plugged in and not charging. Both pieces of good news. I just want to make sure I'm able to preserve all the electric range I can over the life of the car, and it seems as though the Volt does a much better job than the Leaf in taking care of the battery.
 

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...why not ensure that the car will start even when it is cold soaked below -20F? I know it's very unlikely to happen to 99.99% of Volt owners.
If I was parking an ICE vehicle in -20F weather for more than a couple of hours then I'd be sure to have a block heater and I'd plug it in. The same solution works just fine for the Volt.
 

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I didn't notice one while I was under the car, but I'm assuming the Volt doesn't have a 12v engine starter(?) Perhaps the system allows use of the traction battery to start the ICE (via motor or motor/generator), but not for further propulsion electrically if it gets cold enough.
Correct. Not all alone, but pushing the blue button will use the 12v accessory battery (under the floor in the cargo area) to start the car's systems, and the car will operate normally as though it were drained to the low-water nominal charge state. If it's below that, the ICE will start and charge the high voltage pack some. The only time you're really in trouble is if the car gets cold-soaked for a very long time (days) to very cold temperatures (-15F or so) unplugged. In which case it won't start until the car gets warmed up some.
 
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