Help! My drill’s battery won’t charge – is it the tool or the battery?

Hey all, I’ve got a DeWalt 20V Max drill that’s about 2 years old. The battery stopped charging yesterday – no lights on the charger when I pop it in. Tried another battery on the same charger and it works fine, so I know the charger isn’t the issue. The battery itself doesn’t show any damage, but it’s got maybe 3 bars left when I push the test button. Anyone else had this? Is it toast or can I revive it?

Dan, it sounds like the battery’s BMS (battery management system) might have locked up due to a cell imbalance. I’ve seen this happen when a battery gets drained too low. Try a “jump start” – carefully touch the battery terminals to a known good battery’s terminals for a few seconds (pos to pos, neg to neg) to wake up the BMS. But if it’s fully dead, you might need to open it and check individual cells. I always measure voltages on each cell group before calling it quits.

I’d just buy a knockoff from Amazon for $30. My off-brand batteries work fine, even if they don’t last as long. But if you want to fix it, Wendy’s idea is solid. Also check if the contacts are bent – I’ve had a battery not charge because the terminal on the tool was pushed in. Use a toothpick to clean the contacts too.

Thanks for the tips! I tried the boot trick – no luck. I’ll try cleaning the contacts tomorrow. If that fails, I might crack it open. Carl, I get the budget route, but I’ve had knockoffs die in a month. Might spring for a genuine one if I can’t fix it.

I’d recommend sticking with OEM if you can. I’ve seen cheap batteries cause voltage drops that mess with the tool’s electronics. Before you open it, check the battery’s voltage with a multimeter across the main terminals. If it’s below 12V, the BMS definitely locked up. You can try applying 18V from a bench supply to reset it, but careful not to reverse polarity. Good luck!