1. What a leak leaves behind
A leaking alkaline battery releases a liquid that turns to white powder on the metal. That liquid is potassium hydroxide, which eats through metal and can burn skin and eyes.
2. Protect yourself first
Wear gloves and eye protection, and work somewhere ventilated. If it gets in your eyes, rinse with clean water for 15 minutes and get medical help.
3. Take the batteries out
Remove the cells and any broken pieces. Don’t let them roll around loose. Tape both sides of them so they can’t short against each other.
4. Clean the compartment
Wipe the fluid away with a paper towel first. Then dab what’s left with a little vinegar for alkaline, or a paste of baking soda and water for anything else, and wipe again with a damp cloth.
5. Don’t use metal tools
A metal screwdriver or tweezers can spark and short the batteries. Use plastic or wood, and take the batteries out before you start cleaning.
6. Check the device before you power it
If the leak reached the electronics, or the holder is bent or corroded through, have the device checked. Don’t power it on to see what happens.