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oilerlord
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Optimum garage temperature for your EV

Thu Dec 07, 2017 2:48 am

Just curious to get everyone's input on this. Winter is upon us, and our heated garage is set at a constant 54F. My goal is maximizing the battery's lifespan, and thus keeping it at the "best" temperature while parked. I don't leave the car plugged in all the time.
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michael
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Re: Optimum garage temperature for your EV

Thu Dec 07, 2017 4:37 am

That is perfectly fine.
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LeftieBiker
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Re: Optimum garage temperature for your EV

Thu Dec 07, 2017 5:25 am

Yes, "cool but not cold" is great.

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oilerlord
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Re: Optimum garage temperature for your EV

Thu Dec 07, 2017 8:02 am

Thanks, I think so too. I've read the optimum charging temperature range for lithium ion batteries is between 50-86F. I figure staying on the lower end of the scale allows for temperature rise into the middle of the range while charging, and puts less demand on thermal management. After 100K miles, this may only save a few percentage points but it all adds up.

I'd also assume charging on L2 at 13 amps generates less heat than at 30 amps. However, because it takes ~9 hours at 13 amps and only 3.5 at 30 - in terms of minimizing the detrimental effects of heat, which is better? Moderate temperature for a longer period or higher temperature for a shorter period?
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LeftieBiker
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Re: Optimum garage temperature for your EV

Thu Dec 07, 2017 10:39 am

IF the temp doesn't reach the point where acceleration of degradation occurs, then I don't think it matters. DC Fast Charging is generally considered to be fine in cool weather and not so good in hot. I'm not sure that different L-2 rates matter at all...

rgmichel
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Re: Optimum garage temperature for your EV

Thu Dec 07, 2017 3:05 pm

I have my Bolt EV in a garage at about 54 F too. Remember the Bolt is capable of heating and cooling the battery to keep it in the optimum range. I have monitored this over the last month using either a car diagnostic scanner or my ChargePoint charger. I see that if you leave the charger plugged in, the car charges but, about every eight hours afterwards, the car pumps some heat into the battery. Its a few kWh. I have not yet looked at it with the charger unplugged.

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oilerlord
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Re: Optimum garage temperature for your EV

Thu Dec 07, 2017 3:36 pm

LeftieBiker wrote:IF the temp doesn't reach the point where acceleration of degradation occurs, then I don't think it matters. DC Fast Charging is generally considered to be fine in cool weather and not so good in hot. I'm not sure that different L-2 rates matter at all...


No doubt that thermal management will kick in if/when ambient temperatures are a health risk to the battery. I just figure there's no harm in treating the the battery as if was an old Leaf with no BMS. In terms of temperature rise, I'm not sure if different L2 rates matter either but my thoughts are that the pack will remain somewhat cooler charging at 13 amps than it would at 30.

Generally speaking, and other than notable exception of charging a very cold pack, it's pretty much a given that a battery in an EV that gets driven in northern climates and is parked in a temperature controlled garage will last longer than the one in warmer states that isn't.
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IMAdolt
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Re: Optimum garage temperature for your EV

Thu Dec 07, 2017 9:17 pm

IMO it would depend a lot on how your garage is heated/cooled, if it's a burden on your homes energy costs to heat or cool your garage to a stable temperature it's likely more efficient to use the battery TMS to do the work even if it's plugged in and not charging.

If You're the kind of guy who likes a not freezing or boiling hot garage for whatever reason that's a different storey.

devbolt
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Re: Optimum garage temperature for your EV

Fri Dec 08, 2017 12:42 am

We park our Bolt in the driveway, outside. Overnight temps during the winter are typically in the mid to upper 40’s, though we do get a few trips to the mid to lower 30’s. I leave the car plugged in at night.

LeftieBiker
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Re: Optimum garage temperature for your EV

Fri Dec 08, 2017 4:55 am

I just figure there's no harm in treating the the battery as if was an old LEAF with no BMS.


I think you mean "no TMS." The BMS keeps the pack equalized and limits maximum charge and discharge levels.

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