I accidentally drained my two Renogy lithium batteries in my van build by leaving the fans running on some dark days. Now, the solar panels won't charge them. This happened about three years ago, and I'm struggling to remember how I managed to bring them back to life. Should I disconnect the batteries and give them a jump from a car battery? I vaguely recall doing that before, but I've never used a trickle charger or anything like it. Any advice would be appreciated!
2 Answers
It sounds like you triggered the BMS undervolt protection, which keeps the batteries in this state until you get the voltage above a certain threshold. If you are working with a 12V battery, that threshold is likely around 10.5 to 11 volts. Jumping them with a car battery can definitely help, but using a dedicated LiFePO4 charger would be a more reliable option.
Try using a charger that specifically has a lithium mode to wake them up; that seems to work well. Just make sure to follow the proper safety protocols with lithium batteries.”
So I should disconnect them before jumping, right?