I recently bought a 6Ah Flexvolt battery, and although it shows a full charge and I balanced all the cells using a balance charger, it's only reading around 20.10 volts. The DeWalt charger indicates the battery is fine, but when I try to use it in my drill, the LED light flashes when I press the trigger, and the drill doesn't operate. I'm thinking maybe the Battery Management System (BMS) could be faulty, but I'm not sure how to start disassembling it. Any insights?
2 Answers
If the BMS was disconnected at any point, it can permanently shut down, which might be your issue. Just check if you accidentally disturbed the connections at all. This can happen sometimes when trying to revive an old battery. If you’re sure that wasn't the case, then we really need to focus on that battery’s health under load.
Before jumping to conclusions about the BMS being broken, have you checked what the battery voltage is when it’s under load? Sometimes, a battery can show a good voltage when idle but fails to perform under real use. Also, how old is the battery since it left the factory? That can provide some clues too!
That's a good point! If possible, see if you can find the production date on the sticker. In the meantime, testing it under load with a high wattage resistor might give you some useful info.