On-Route Preconditioning when battery is already hot, Battery Warming @ 254kW?

[fiehlsport]

On my trip this weekend, my car wanted to precondition and continue battery heating even during a charging session, despite extremely hot temps.

I was driving (quickly) for about three hours straight and pulled into a Supercharger. Ambient temp was 85F. The last 5 minutes it was preconditioning the battery on the way to the supercharger. Thought it was odd, but maybe it wanted a few extra degrees for optimal charging...

Plugged in, was getting 254kW(!) and it said it was heating the battery the entire time. Why even bother if it's already getting 254kW?? Usually the battery needs *cooling* at that charging rate, not heating, especially in the summer. I've supercharged slower, in cooler temps, and it's always cooled the battery.

This behavior seems different than what I've seen on prior builds, I've supercharged plenty in the hot summer and rarely ever saw preconditioning, let alone the battery heating message during a perfect charging session. Screenshot attached...

Maybe a different software strategy is being employed now than what I've seen in the past? Anyone else seeing this behavior?

 

[GtiMart]

At 254kW while preconditioning, on an AWD 6.5-7kW would be used for heating, plus your AC energy, so you wouldn't quite be receiving 250kW in the battery. Sounds pedantic but I want to list the details. I believe I've seen my car heat until it would get warm enough for its taste while supercharging and then immediately turn on cooling. Maybe your battery wasn't quite at 50C or more yet.

 

[AAKEE]

On my trip this weekend, my car wanted to precondition and continue battery heating even during a charging session, despite extremely hot temps.

I was driving (quickly) for about three hours straight and pulled into a Supercharger. Ambient temp was 85F. The last 5 minutes it was preconditioning the battery on the way to the supercharger. Thought it was odd, but maybe it wanted a few extra degrees for optimal charging...

The battery doesnt seem to get more than 40-45C even if driving at 85F.
The target for cooling both active (65C) and passive (60C) are higher than that.
Driving even hot days probably need a little precondition to reach 48C for SuC V3.
(The preheating for SuC V2 got lowered one year ago to about 38-40C).

Plugged in, was getting 254kW(!) and it said it was heating the battery the entire time. Why even bother if it's already getting 254kW?? Usually the battery needs *cooling* at that charging rate, not heating, especially in the summer. I've supercharged slower, in cooler temps, and it's always cooled the battery.

The power you read is total power from the stall, so minus the preheating and minus the AC or heating and the cars other power draw. Just like @GtiMart says.

I have logs of 261-262kWh and the bsttery charging power was just briefly 251.75kW, otherwise 250kW. The ”overshoot” is battery heating etc.

This behavior seems different than what I've seen on prior builds, I've supercharged plenty in the hot summer and rarely ever saw preconditioning, let alone the battery heating message during a perfect charging session. Screenshot attached...

Maybe a different software strategy is being employed now than what I've seen in the past? Anyone else seeing this behavior?

It has been like this for at least 2.5 years.

The car preheats the battery (M3P 2021 with the 2170L 82 kWh as example/data source):
For SuC V3 the car preheats to about 48C cell temp, but the temperature target is about 55C for active heating and the cooling target is 60C. (Temp targets the same for my 2023 MSP). So the car like the battery to reach 55C before the SOC gets high.

The battery probably need high temp a bit up in SOC, to reduce lithium plating and to keep the internal resistance low to get high charging speed at higher SOC.