Cold weather battery conditioning vs driving efficiency

[MountainBikeDude]

I’ve also noticed that speed of charge has a direct, immediate effect on battery temps. Trickle charge on a 20-amp outlet, essentially zero effect on battery temps. Last night I charged outside here in Minnesota at about 20F, on my 48 amp Rivian charger, and over night the battery went from 47 to 59F. When I stop at a high-speed charger pumping out 250-300Kw, the battery temp will go up 30+ degrees in ten minutes.
So the faster you pump juice into the car, the higher the battery temps will go. Most people here probably already know that, but for the newbies, that little factoid might come in handy someday.

The battery will also protect/prime itself when plugged into a DCFC to get it to an optimal charging temperature, so if cold, it will use the motors as heaters sacrificing some of the incoming power to get the battery up to that desired 20ish degrees C as quickly as possible. If you're Level 2 charging at 11.5kW and below, there isn't much need for the battery to condition prior to charging because the C rate is quite low in comparison.

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[Lawrence-of-Blaine]

The battery will also protect/prime itself when plugged into a DCFC to get it to an optimal charging temperature, so if cold, it will use the motors as heaters sacrificing some of the incoming power to get the battery up to that desired 20ish degrees C as quickly as possible. If you're Level 2 charging at 11.5kW and below, there isn't much need for the battery to condition prior to charging because the C rate is quite low in comparison.

C rate? Meaning?

 

[DayTripping]

Here, this will help. Battery university is a great source of info.

https://batteryuniversity.com/article/bu-402-what-is-c-rate

This is a great read for charging (non LFP) batteries like in the large and max packs.

https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

 

[MountainBikeDude]

C rate? Meaning?

Basically charge rate of a battery from 0-100% capacity over an hour as well as discharge rate over the same period.

1C: The battery charges completely in one hour
2C: The battery charges completely in half an hour
0.5C: The battery charges completely in two hours

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