In the EC source code:
./chromium/src/platform/ec/zephyr/dts/bindings/battery:
atl,framework55w.yaml ← The FW13 55W battery charge max = 55 C, discharge max = 70 C
atl,framework61w.yaml ← The FW13 61W battery charge max = 55 C, discharge max = 70 C
atl,framework85w.yaml ← The FW16 85W battery charge max = 55 C, discharge max = 70 C
The battery charge min = 0 C, discharge min = 0 C
This is where the EC uses the battery temp to limit what it does.
You can look in those files for more details of the limits.
If the battery is charging slowly at 19C, as none of the limits identified above relate to 19C, I don’t think it is slow due to temperature.
It might be slow based on buggy EC charge/discharge code.
Also, looking at that other thread, the 19C is not the temp of the battery. It is not reading the temp from the battery, so in those cases, the battery could be any temp, as it is warmed by the CPU.
The problem is the EC code, as it stands, reads the battery temp and uses it in its charging decisions. It does not pass the battery temp to user space, so the user can view it.
I have a modified EC source code that does give the battery temp to the user.
I have seen, ambient temp 17C, battery temp 35C when the CPU is mostly idle.
If the CPU is being used, I could see this battery temp reaching 55C, and thus the EC would stop charging until the temp drops again.