Symptoms
- Battery or drill works only when wiggled into a certain position
- Green, white, or dark film visible on the metal contacts
- Battery was stored in a damp or humid location
- Power cuts in and out during use
Likely causes
- CommonCorrosion from humidity or moisture exposureMetal contacts oxidize over time, especially in damp garages or basements.
- CommonDust and grime buildup mixed with minor oxidationA combination of dirt and light corrosion has the same effect as heavier corrosion alone.
- PossibleBattery stored for a long time without useExtended storage, especially in humid conditions, promotes contact oxidation.
- PossibleBattery exposed to water or a spillDirect moisture exposure accelerates corrosion significantly.
What to do
- Remove the battery and inspect both its contacts and the tool's contacts for discoloration or film.
- Use a pencil eraser, fine sandpaper, or a contact cleaner on a cloth to gently clean the metal contacts.
- Avoid using water, which can worsen corrosion; stick to dry cleaning methods or electronics-safe contact cleaner.
- Reinsert the battery firmly and test the tool.
- Store batteries and tools in a dry area going forward to prevent recurrence.
- If corrosion is severe or the battery has visible internal moisture damage, replace it rather than continuing to use it.
Tools and parts
- Fine sandpaper or pencil eraser
- Electronics contact cleaner (optional)
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.