Do LifePO4 batteries “warm up” in cold temps when charging from low wattage?

[Rocksnsalt]

Maybe this is an odd or dumb question but I’m wondering if LifePO4 batteries slowly “warm up” when connected to solar panels at the beginning of the day?
My use case here is I have a Bluetti AC200MAX connected to a used 315w solar panel I picked up cheap. it works great and I’ve actually seen it produce 335W at times.
I connected the solar panel before the sun was actually up over the mountain near me.
So the bluetti showed 7 to 10 watts charging at that time (around 745am). Being that the temp was 32F at 745am I have concerns the Bluetti battery pack may be under 32f.
I cannot find any info regarding does the ac200max have low temp charge protection (Or hi for that matter).

So I’m wondering does a LifePO4 battery slowly warm up once receiving a charge?

Edit 930am , just checked on charge progress an hr or so later and no charging going on though ambientbtemps has warmed at least 10f.
The bluetti shows bms temp error so apparently low temp protection kicked in, just odd that it did so an hour+ later as outside temps were warming. I’m guessing the bluetti unit / bms itself still had conductive momentum and losing temp.

 

[BentleyJ]

Since LiFePO4 likes to be charged at 0.2C to 0.3C and has low internal resistance, there isn't much "waste" heating at these relatively low current levels. This is the reason for external heater pads and insulated enclosures in cold temps.

 

[Rocksnsalt]

Since LiFePO4 likes to be charged at 0.2C to 0.3C and has low internal resistance, there isn't much "waste" heating at these relatively low current levels. This is the reason for external heater pads and insulated enclosures in cold temps.

Appreciate the response. Can you translate what ”likes to be charged at 2C to .3C “ is in watts or amps?
I certainly understand re external heating pads and insulation.
The van it sits in is fully insulated, but that’s just 3M Thinsulate SM600L which is only about R5 if I recall correctly.
The van is still a big metal box sitting in the cold.
So heating pads are in our future, yes.

 

[Horsefly]

I don't think he's still around, but a forum member by the name of Bill Taylor posted (in a thread I started in 2021) that he did an experiment and found that LFP cells did warm when discharging at 0.25C, but didn't see much warming when charging. His post his here: https://diysolarforum.com/threads/on-keeping-lfp-warm.17629/post-206713

 

[fratermus]

likes to be charged at {.}2C to .3C “ is in watts or amps?

C is the battery capacity in Ah. If the battery is 200Ah the .3C rate is 60A (200Ah x 0.3).

Note the post you are quoting said .2C, not 2C. Using the 200Ah example it's the difference between 40A and 400A.