What battery does my smoke detector take?

Smoke alarms run on a 9V, on AA batteries, or on a sealed 10-year battery, and hardwired alarms may have an AA or 10-year backup.^{[1 · Oct 29, 2026][2 · Oct 29, 2026]} The battery type is on the label on the back of the alarm.^{[3 · Oct 29, 2026][1 · Oct 29, 2026]}

How to check yours

1. Read the label on the alarm, or check its manual.^{[1 · Oct 29, 2026]}
2. Note the date code on the back too; it tells you how old the alarm is.^{[1 · Oct 29, 2026]}
3. Use the battery the label lists. Kidde says off-brand or old batteries can trigger low-battery mode.^{[1 · Oct 29, 2026]}

How often to change it

• Replaceable battery: at least once a year, and right away if the alarm chirps.^{[3 · Oct 29, 2026][4 · Oct 29, 2026]}
• Sealed 10-year alarm that chirps: replace the whole alarm.^{[3 · Oct 29, 2026]}
• The alarm itself: Kidde says to replace smoke and heat alarms every 10 years, and CO or combination alarms every 7 to 10 years.^{[5 · Oct 29, 2026]}

Swapping the battery

1. Line up the + and − ends with the markings in the battery bay.^{[4 · Oct 29, 2026]}
2. Close it up and press the test button.^{[4 · Oct 29, 2026]}
3. Use a sturdy step stool or ladder.

Old alkaline 9V and AA batteries can go in the trash in most communities, though the EPA recommends a battery recycler. Lithium batteries, which some alarms use, shouldn't go in the trash.^{[6 · Oct 29, 2026][7 · Oct 29, 2026]}

Sources: 1. Kidde, What type of battery does my alarm use?. 2. Kidde, i9050 battery operated smoke alarm product page. 3. NFPA, Changing clocks and batteries. 4. Kidde, How do I replace my smoke alarm's battery?. 5. Kidde, Alarm replacement guide. 6. US EPA, Used household batteries. 7. US EPA, Used lithium-ion batteries. Checked Oct 29, 2026. Inch conversions are our own arithmetic from the millimeter figures. Brand names and trademarks belong to their owners; specs are restated in our own words and tables, not reproduced.