Cordless drill battery won't charge

Symptoms

• Charger light doesn't turn on when battery is inserted
• Light blinks red or an error color and stays that way
• Battery shows full but drill has no power
• Charging takes far longer than usual

Likely causes

• CommonBattery pack has reached end of lifeLithium-ion batteries typically last 2–5 years or a few hundred charge cycles before they can no longer hold a charge.
• CommonBattery sat fully discharged for a long timeDeep discharge can trip a protective circuit that some chargers can't wake back up.
• PossibleDirty or corroded contacts on battery or chargerA film of dust or oxidation blocks the connection needed to start charging.
• PossibleCharger itself has failedChargers can fail from age, a power surge, or a damaged cord.
• PossibleBattery or charger overheated and is in a protective cool-down stateSome packs won't charge until they cool to a safe temperature range.

What to do

1. Wipe the metal contacts on both the battery and the charger with a dry cloth.
2. Confirm the charger is plugged into a working outlet by testing another device in the same outlet.
3. Let a warm battery cool to room temperature for 30 minutes, then retry, since heat can block charging.
4. Try a different battery in the same charger, and the questionable battery in a different charger if either is available, to isolate the faulty part.
5. Watch the charger's indicator light pattern and compare it to the manual; a fast-blinking or specific color often signals a bad cell.
6. If nothing changes after cooling and cleaning, the battery pack is likely dead and needs replacement.

Tools and parts

• Dry cloth

When to call a pro

Don't try to open or repair a lithium-ion battery pack yourself; if it's swollen, hot, or smells odd, stop using it and dispose of it at a battery recycling center rather than attempting a fix.

Safety