Why won't my drill battery hold a charge?

Hey everyone, newbie here. I've got a 20V drill that's about 2 years old. The battery charges fully, but as soon as I put it in the drill and pull the trigger, it dies after a couple of seconds. Even fully charged, it barely spins. I've tried cleaning the contacts, but no luck. Any ideas? Is the battery done for?

Hey DIYDan, sounds like a dead cell or two in the pack. Even if the charger says fully charged, the voltage under load drops if a cell is weak. Best way to test is with a multimeter - check voltage at the terminals when it's charged and then when you pull the trigger (if it drops below like 15V under load, cells are toast). If you're handy, you can rebuild the pack, but for most, just buy a new one. Make sure to recycle the old one!

I've had that happen too. Sometimes it's the battery, but also check the drill itself - maybe the trigger switch is going bad. Inside the trigger, there's a potentiometer for speed control. If it's dirty or worn, it can cause the drill to act like it's dying under load. Try a couple of different batteries if you have them. If all do the same, it's the drill. But since you said the battery dies after seconds, I'd bet on the battery. Also, those lithium packs can develop a 'memory' issue if you always run them dead - try reconditioning by charging, discharging, charging again.

Listen to these fellas, they're on the right track. I've been in the trades 40 years. That sounds like a bad cell in the pack. Here's a trick: if you have an 18V drill and this is a 20V max, those are essentially the same. Voltage drop under load is the killer. Sometimes you can 'jump start' a dead cell by charging it with a 9V battery directly for a few seconds - but that's a temporary fix and can be dangerous if you don't know what you're doing. My advice: replace the battery. Don't bother rebuilding unless you're comfortable with spot welding and battery management. And when you buy a new one, get a genuine brand replacement, not those cheap knockoffs - they'll let you down. Also, store batteries in a cool place, not in direct sunlight in your garage. Good luck!