Smoke Alarm Batteries and That Chirp

A chirp every 30 to 60 seconds is the smoke alarm's way of asking for help. Most of the time it is the battery. Sometimes it means the whole alarm is done.

How often to change batteries

• Alarms with replaceable batteries: at least once a year, and right away when the alarm chirps.
• Hardwired alarms usually have a backup battery. It needs replacing on the same schedule, even though the alarm runs on house power.
• 10-year sealed alarms never need a battery change. When they reach the end of their life they chirp, and the entire alarm gets replaced.

Use the exact battery type listed on the alarm or in its manual. Some models call for a specific type or even specific brands, and the wrong battery can shorten the warning time you get.

Changing the battery

1. Take the alarm down. Most twist off their base. On hardwired alarms, unplug the connector if needed, or turn off the circuit if the manual says to.
2. Swap the battery. Put in a new one, matching the plus and minus marks. Make sure the battery door closes all the way.
3. Put it back and test it. Press and hold the test button until it sounds.

Still chirping after a new battery?

• The battery door is not fully closed, or the pull tab on a new battery is still in place.
• Some alarms remember the low-battery warning for a while. Press and hold the test button for 15 to 20 seconds to clear it, if your manual says so.
• Dust or bugs in the sensor. Vacuum the vents gently.
• Big temperature swings or humidity near the alarm.
• The alarm has reached end of life. Check the date. Ten years old means replace it.

Getting rid of an old alarm

Ionization alarms contain a very small amount of radioactive material. Rules for disposal vary, so check the manufacturer's instructions and your local waste program. Some manufacturers run take-back programs. Pull removable batteries out and recycle them where you can.