AA batteries leaked white or blue crust in device

Symptoms

• White, blue, or greenish crusty buildup on battery terminals
• Device won't power on since batteries were left in
• Batteries feel wet, swollen, or the wrapper is split
• Corrosion visible on the metal springs or contacts

Likely causes

• CommonBatteries left in an unused device for monthsAlkaline batteries slowly leak gas and electrolyte as they age, especially left in idle devices.
• CommonMixing old and new batteries, or different brandsUneven discharge between cells increases the chance one leaks.
• PossibleDevice left in a hot environmentHeat speeds up the chemical breakdown that causes leaks.
• Less commonManufacturing defect in the batteryOccasionally a battery fails and leaks even when new.

What to do

1. Put on gloves and, if you have them, safety glasses before touching the corrosion.
2. Remove the leaked batteries carefully and dispose of them, without touching the residue with bare skin.
3. Dip a cotton swab in white vinegar (for alkaline leaks) and gently scrub the crust off the contacts.
4. Wipe with a dry cloth, then let the compartment air-dry fully before inserting new batteries.
5. If corrosion has eaten into the metal contacts, gently scrape with a small flat tool or fine sandpaper to restore contact.
6. Wash your hands after handling, and wipe down any surface the batteries touched.
7. If the device still won't power on after cleaning, the contacts may be damaged beyond repair.

Tools and parts

• Gloves
• Cotton swabs
• White vinegar
• Small flathead screwdriver

When to call a pro

If corrosion has damaged the device's circuit board rather than just the contacts, a repair shop or the manufacturer can assess it.

Safety