I have two of the same batteries(bought second hand). When charging, one shoots to 15V and the other sticks to 13.3V. So I decided to charge only the second battery with a 12V 25Amp charger, but now it sticks at 13.6V. Is that a problem? Is the battery broken?
The vast majority of LFP charging occurs between 13.2 and 13.8V. The run to 14.X happens at the very end.
If you can confirm:
1) current is still flowing into the battery
2) the battery is not getting warm
then you just need to keep charging it until it gets full.
