My cordless drill battery won't charge - any ideas?

Hey everyone, having a weird issue with my DeWalt 20V drill. The battery won't charge at all - when I put it on the charger, the light just blinks red. Tried cleaning the contacts, no luck. It's only about a year old. Anyone dealt with this before?

OP - seen this a few times on jobsites. First, check if the charger itself is working - try another battery if you have one. If the charger's good, that blinking red usually means the battery's protection circuit tripped. Sometimes leaving it off the charger for 24 hours resets it. If not, might be a dead cell. What model charger are you using?

I had this happen with my Ryobi! Turned out the battery terminals were just a tiny bit corroded. I used some electrical contact cleaner and a small wire brush - fixed it right up. Also make sure the charger is plugged into a good outlet, my garage outlet was acting up once.

Important safety note here: If the battery is getting hot or swollen at all, DO NOT try to charge it. That's a fire hazard. Take it to a proper recycling center. Also, make sure you're using the manufacturer-approved charger - mixing brands can cause issues.

Sparky's got it right - probably the protection circuit. DeWalt batteries have a tendency to do this if they get completely drained. Try the 24-hour trick. If that doesn't work, check if it's still under warranty. Pro tip: Always store your batteries at about 50% charge, not fully charged or dead.