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Discussion Starter · #1 ·
I have a level 2 charger for my 2018 Volt.
It is on the side of my house and I can hear anytime the relay ‘clunks’ open or closed. Obviously I hear it when charging starts or finishes- or when I precondition the car.
But I also hear it at other times- turning on for a relatively short time generally.

Is this just drawing power to help keep batteries warm? The ‘charging’ light on the dash does not come on when this happens.
I have not noticed any documentation on this.

Not a big deal, just curious.
Mark
 

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I have a level 2 charger for my 2018 Volt.
It is on the side of my house and I can hear anytime the relay ‘clunks’ open or closed. Obviously I hear it when charging starts or finishes- or when I precondition the car.
But I also hear it at other times- turning on for a relatively short time generally.

Is this just drawing power to help keep batteries warm? The ‘charging’ light on the dash does not come on when this happens.
I have not noticed any documentation on this.

Not a big deal, just curious.
Mark
Yes, the Volt can periodically draw power to heat or cool the battery whenever it is plugged in. The Volt is not drawing the power needed to keep the battery temperature from falling below 32F from the high voltage battery so if the Volt's battery is already fully charged charged the charge indicator light will not start flashing even though the EVSE indicator light may indicate that power is being supplied to the Volt. The battery heating unit draws ~ 1kW while actively heating the battery and may run for 10 - 15 minutes every hour or two. The worst case, in extreme cold weather, is that keeping the battery warm costs $0.50 - $0.75 per day depending on your cost for electricity.
 

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My clipper creek does this. It's just battery maintenance (heating/cooling). Mine will do it throughout the day if the weather is extreme. It's usually on for 15 minutes at a time and completely normal. For mine the "charging" light always illuminates, but maybe if it's not drawing the full capacity from the EVSE, it may not display the charging light since it knows it's just doing maintenance. Overall, proof to me that you should keep the car plugged in whenever possible. Without being plugged in it would not be able to do that maintenance.
 

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Other reasons it might come on include to provide the 12V battery with an occasional maintenance charge, and obviously if you precondition the vehicle.
 

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Discussion Starter · #5 ·
Thanks, all that makes sense and what I suspected.
It is not all that cold here generally (freezing fairly rarely)- but sometimes in the 30’s and very often in the low 40’s.

I didn’t think about the 12V battery too much, but I have almost all my other vehicles (that have batteries) on a ‘Battery Tender’ float charger, and it is good they charger will keep it topped up.

Mark
 

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Be glad it does this. If you bought a Leaf, the battery would just sit there and "freeze to death", as it has no active TMS. Not even the new one, but maybe the long range one not quite out yet.

Leaf owners end up with levels of battery degradation unheard of in a Volt. Being in Minnesota where it gets quite cold and with an unheated detached garage, this is not an insignificant issue for us.

I try to encourage people considering a Leaf to take a look at the Bolt EV instead, for this very reason. Most seem to be blissfully unaware and just assume the Nissan MUST be better than a Chevrolet.

I get a warm and happy feeling when I'm out in the garage on a bitter cold day and hear the TMS running.

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Be glad it does this. If you bought a Leaf, the battery would just sit there and "freeze to death", as it has no active TMS. Not even the new one, but maybe the long range one not quite out yet.

Leaf owners end up with levels of battery degradation unheard of in a Volt. Being in Minnesota where it gets quite cold and with an unheated detached garage, this is not an insignificant issue for us.

I get a warm and happy feeling when I'm out in the garage on a bitter cold day and hear the TMS running.

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Cold temperatures alone will not damage a lithium-ion battery pack. Battery efficiency drops at lower temperatures, steeply below ~25F. Charging a lithium-ion battery at low temperatures (below 32F) will damage the battery as lithium metal dendrites will form on the anodes causing loss of capacity, creating internal shorts within the cell and making the battery permanently unsafe for use. This is a real issue and must be avoided, so the battery must be warmed to proper temperature prior to charging. Heat is the main culprit when it comes to degrading a lithium battery, proper cooling of the battery pack will help ensure the battery capacity does not excessively degrade over time. If you leave your Volt plugged in, even if you have set a minimal TOU schedule for charging, the Volt will always be ready to drive, have no issues with charging or being charged through regenerative braking or if the Volt is operated in Mountain Mode. Unlike the Volt's high voltage traction battery, the Volt's 12V AGM battery is not warmed by the Volt's TMS. Although unlikely, the 12V AGM battery could freeze in extreme cold conditions. A portable jump starter (kept warm) would be the quick fix in this situation to get the Volt running.
 

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Very interesting thread.

I am aware of the damage that high temperatures can do to the high voltage battery, and make sure to keep it plugged in over the summer months.

Other than reduced range and efficiency, however, do subfreezing temperatures actually physically harm an unplugged Volt’s traction battery?

Since we now have more than one Volt, in the winter time I will from time to time have to leave one unplugged for extended periods outside.

Thanks
 

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Cold temperatures alone will not damage a lithium-ion battery pack. Battery efficiency drops at lower temperatures, steeply below ~25F. Charging a lithium-ion battery at low temperatures (below 32F) will damage the battery as lithium metal dendrites will form on the anodes causing loss of capacity, creating internal shorts within the cell and making the battery permanently unsafe for use. This is a real issue and must be avoided, so the battery must be warmed to proper temperature prior to charging. Heat is the main culprit when it comes to degrading a lithium battery, proper cooling of the battery pack will help ensure the battery capacity does not excessively degrade over time.
Thanks very much. This is just what I was after. So does the volt warm up the battery before it actually starts sending current into it when charging when it’s cold?


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Cold temperatures alone will not damage a lithium-ion battery pack. Battery efficiency drops at lower temperatures, steeply below ~25F. Charging a lithium-ion battery at low temperatures (below 32F) will damage the battery as lithium metal dendrites will form on the anodes causing loss of capacity, creating internal shorts within the cell and making the battery permanently unsafe for use. This is a real issue and must be avoided, so the battery must be warmed to proper temperature prior to charging. Heat is the main culprit when it comes to degrading a lithium battery, proper cooling of the battery pack will help ensure the battery capacity does not excessively degrade over time.
Thanks for the technical correction. We learn a great deal from you.

So in other words, our local Leaf owners may be harming the batteries by charging at low temperatures. Plus it does actually get hot here in the summer, believe it or not, and that is leading to degradation over time.

Either way, better to get an EV with TMS than without.

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Thanks for the technical correction. We learn a great deal from you.

So in other words, our local Leaf owners may be harming the batteries by charging at low temperatures. Plus it does actually get hot here in the summer, believe it or not, and that is leading to degradation over time.

Either way, better to get an EV with TMS than without.

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I am not familiar with the Leaf but have to believe that the Leaf will delay charging the battery until the battery is warm enough to safely charge. I don't know whether that means the Leaf has some type of resistance heating element located underneath the battery that can warm the pack.
 

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In terms of protecting the Volt battery from damage caused by charging on cold days, what are the best practices to observe?

Is the Volt smart enough to run the TMS to get it up to temperature before letting electricity go into the battery?
Is it necessary/helpful to run the internal combustion engine for a bit prior to charging to raise the coolant temp circulating in the car?
Is the battery generally warm enough after driving in cold temps to just plug in on arrival from a trip?

I have a home without a garage and charge in my driveway, so particularly interested in this.
 

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I am not familiar with the Leaf but have to believe that the Leaf will delay charging the battery until the battery is warm enough to safely charge. I don't know whether that means the Leaf has some type of resistance heating element located underneath the battery that can warm the pack.
You are correct, I just looked it up. The Leaf does have a heater to keep the battery from getting too cold.

I've always read that the Leaf has no active TMS, but that's really not entirely true after all. What it does lack, however is active cooling, so hot weather will lead to battery degradation in a Leaf.

I do wonder if the resistance heater in the Leaf is as effective though as the liquid TMS in a Volt or Bolt EV.

I've read plenty of articles about battery degradation in Leafs, and articles critical of the fact that it lacks the kind of active TMS that GM, Tesla and many others use.

And I'm getting off topic.....

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12V batteries in cold aren't a problem. They operate just fine in cold temps. Lived on the Prairies many years with temps dropping to -20 to -40 many times. Of course the engines are plugged in with a block heater to keep the oil warm enough so the reduced 12V battery could turn it over and start. I don't plug the Volt in unless it drops enough below freezing that I would want to precondition it to get the cabin a little warmer but mostly so the windows are clear. Here when it drops below freezing it's dry so plugging it in (it's outside under a tarp lean to) is not a problem and if it's raining it's above freezing so don't plug it in.
 

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Discussion Starter · #15 ·
Here when it drops below freezing it's dry so plugging it in (it's outside under a tarp lean to) is not a problem and if it's raining it's above freezing so don't plug it in.
I’m just across the Straits, sometimes I get frost on the windows, and the precondition is great for helping clear windows.
But indeed- most times if freezing it is not raining (rarely snow).

I park it outside and leave it plugged in all the time. (Too many motorcycles in my garage to park the Volt)
 

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I’m just across the Straits, sometimes I get frost on the windows, and the precondition is great for helping clear windows.
But indeed- most times if freezing it is not raining (rarely snow).

I park it outside and leave it plugged in all the time. (Too many motorcycles in my garage to park the Volt)
I live in Maple Bay and rarely see frost on the windshield yet when I drive the 10 Km. into Duncan I see frost on the Windows of many cars. Living a few miles inland or up a little higher can make all the difference when it's marginal. I like the precondition so I don't have to defog.

My Volt is outside because I have a TR7 in one bay and a Tercel Wagon in the other that are being restored. my days of motorcycling are past (unless I could find a 1968 Triumph Trophy like a had back then). :p
 

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Other reasons it might come on include to provide the 12V battery with an occasional maintenance charge, and obviously if you precondition the vehicle.
Is this true? I thought the 12V battery would only be maintained if the Volt is On.
 
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