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I've read through the posts on this topic but didn't find much and what is out there is a bit on the old side. So, I was wondering if people who have been using Chevy Volt batteries (Gen 1 in particular) in EV conversions would have some insight for me.
I am putting a full set 2013 Volt battery into my S10 and I am wondering what to do with cooling and heating.
I know that GM keeps the battery temperature in a fairly narrow range, however, let's say that I don't do any cooling nor heating … what would the problems really be ...
1. would summer temperatures of around 150F (counting on truck sitting in the sun for hours)
  • just reduce the range, or
  • would it significantly shorten the life of batteries, or
  • would it cause immediate damage?
  • does it matter if they are just exposed to that temperature, or is it a problem only if they are charged/discharged while at that temperature?
2. How high of a temperature could batteries live with and not have significant long term damage or rapid reduction of life? For example, if I only keep them from going over 100F (in those hot summer days) would that avoid rapid deterioration?
3. Similar questions regarding cold (Northern Illinois) temperature:
  • If batteries are exposed to low temperature (such as 15F-ish) and they are not charged/discharged at the time, how bad is it? Does it cause long term or immediate damage, or is it only bad if I was to try to drive the truck
  • If I was to keep the batteries from going below freezing temperatures (and not drive the truck) would that save them from significant long term damage?
Sorry for a longer post … any input is appreciated.
 

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Longevity and even small increases in temperature are inversely related.

Very hot conditions can cut lifetime by 80-90%.

Just as true for storage as while in use.

This is the case for every chemistry I've heard of being used for propulsion.

There is no hard B&W line, but a curve relationship. Hotter is worse, cooler is better, until you run into charging rate issues, say below 15-20°C

Storage isolated at low SoC is ideal in even freezing conditions, but then the cells need warming in order to discharge efficiently.

Charging, the closer to freezing the slower the rate needs to be.

Fast charging (over 0.5C) is best over 25-30°C
 

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As long as you avoid the extremes you should be OK
I have the cooling system hooked up to circulate the coolant - I believe that without that you may end up with localised hot spots
But no cooling or heating except I pass the coolant through my controller to cool the controller

Saying that I'm in Southland NZ - it does not get that hot here - and when its damn cold I don't drive my car much as its lacking in creature comforts
 

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I don't think you'll see 150f inside the pack when sitting. Sure, you'll get that inside the cab. But, are you putting the batteries in the cab?

I would guess that your pack is out of the sun, like under the truck bed? As long as you don't have any sun load, you shouldn't see a huge raise over ambient temperature when parked.

You might need cooling when driving, just depends on how much current you're pulling from the battery. I'd go on the side of caution and plan for cooling and heating the pack. Maybe building so it can easily be added once the vehicle is in use if needed.

Pay attention to what John61 said above. Charging should be limited even at cool temps. 15c is 59f
The cells I have a spec sheet handy with say not to charge at all below 0c and limit discharge.
If your winters are below freezing, you should probably include battery heating.
 

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Discussion Starter #5
Thanks for your insight guys!

Unfortunately, I didn't go with "under the bed" battery mounting. The battery is mounted in the bed, instead. I intend to use the original (Volt) cover/enclosure so the battery pack will be sealed. Still, being in the bed it would be exposed to direct sun and that's why I threw 150F as a possible temperature after (worst case and maybe unrealistically high) sitting in the sun for hours. To avoid direct sun exposure I could use a bed cover, but unfortunately it happens to be black so it actually may make it worse. Either way, I take it I should utilize liquid cooling even if it means to keep the batteries at ambient when parked and to help with temperatures when driving.
Speaking of driving/discharge … for me, working on the EV and driving it is for fun. In that, there are times when I want to see the motor amps needle go over 1000A and to feel the kick in the back ... hopefully even some squeal from the tires. Having been designing lower HP motor controllers for 25-ish years it felt good to design something that gets up there in terms of power. So, my MaxForcer controller is set to limit motor amps to 1200 A and battery amps to 800 A (hopefully somewhat close to 400 A from each string). I know that challenges battery longevity, but the question in my mind is how much and what makes sense to do to avoid/reduce the damage. Normal cruising at 60mph or so will cause about 100 from the battery pack (50-ish per string).

In your answers above you guys say that at cold temperatures charging rates need to be limited/reduced. I take it that means I should make sure that my charging rate would needs to go down to 0.2C or even 0.1C if I was ever to charge the batteries in, let's say, 5-10C ambient. Assuming that charging is as bed as discharging does that mean I shouldn't even think to drive (leave the garage) in those temperatures? Or, is charging somehow worse than discharging for betteries that are cold?

By the way, I don't have a need nor do I plan to drive it when it is really cold - I am asking more so to understand the effects and to figure out what kind of a system for cooling/heating I should go for.

Thanks
 

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To put the effects of heat into perspective, there are only minor differences between the battery chemistry used in the Gen 1 Chevy Volt and Gen 1 Nissan LEAF. There are Volts with many hundreds of thousands of miles with only minimal battery degradation, while there are similar LEAFs that have lost 50% or more of their original capacity.

If you can keep the internal battery temperature to less than 100 F, you should still be within operational tolerances for the battery (even per GM's thermal management parameters). However, there is a reason GM uses the AC system to cool the battery. Cycling ambient air doesn't provide enough cooling, especially when driving and discharging the batteries, which can push the temperatures way past 100 F if not actively cooled.

Cold temperatures shouldn't be as much of an issue unless you're trying to draw power from or recharge the battery when it's extremely cold.
 

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To Ladogaboy's point - the Volt needs the cooling because it has to operate in places like Nevada and the American deserts
In more temperate places - simply NOT a problem
I'm cruel to my battery - I draw up to 1200 amps and use the car on the track
The highest temperature I have seen was less than 30C -
IMHO the reason the Volt batteries are so much better than the Leaf is the coolant flow - NOT the maximum temperatures but the temperature equalisation - when the coolant is flowing you simply won't get any localised hot spots
 

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To Ladogaboy's point - the Volt needs the cooling because it has to operate in places like Nevada and the American deserts
In more temperate places - simply NOT a problem
I'm cruel to my battery - I draw up to 1200 amps and use the car on the track
The highest temperature I have seen was less than 30C -
IMHO the reason the Volt batteries are so much better than the Leaf is the coolant flow - NOT the maximum temperatures but the temperature equalisation - when the coolant is flowing you simply won't get any localised hot spots
I think it really depends, though. Ambient temperature matters, but I wouldn't discount the impact of heavy loads, both charging and discharging. Bjorn Nyland, in testing Nissan LEAFs on long distance runs, regularly gets the internal battery temperature up to 50 C (over 120 F) even when the outside temperatures are 0 C (32 F) or colder.
 
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