9V battery corroded in smoke detector

Symptoms

• White or crusty buildup around the 9V battery terminals
• Smoke detector chirping or silent when it shouldn't be
• Battery feels swollen or the wrapper is split
• Corrosion visible on the metal snap connector inside the unit

Likely causes

• CommonBattery left in place well past its replacement interval9V batteries in smoke detectors should be replaced at least once a year, more if it's chirping.
• PossibleBattery is a cheap or expired brand prone to leakingLower-quality batteries leak more readily as they age.
• Less commonDetector unit itself is old and its battery contacts are wornVery old smoke detectors can have degraded connector clips.

What to do

1. Test that you're not dealing with an active fire or smoke event before doing anything else.
2. Put on gloves before touching the corrosion.
3. Remove the corroded battery carefully, avoiding contact with the crusty residue.
4. Clean the metal snap connector inside the detector with a cotton swab dipped in white vinegar, then dry it fully.
5. Install a fresh, name-brand 9V battery and test the unit using its test button.
6. If the detector doesn't respond to the test button after a fresh battery and cleaning, replace the smoke detector itself, since most have a 8–10 year service life anyway.
7. Set a reminder to replace smoke detector batteries yearly, such as with a clock change.

Tools and parts

• Gloves
• Cotton swabs
• White vinegar

When to call a pro

If the detector fails its test after a fresh, clean battery, replace the unit rather than troubleshooting further, since smoke detectors are inexpensive safety devices.

Safety