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In short
Kidde says an alarm can hold onto a weak-battery error even after you replace the battery. Reset it: take the battery out, hold the Test button for at least 15 seconds, then put the battery back. First Alert says 15 to 20 seconds. If it still chirps after a reset and a fresh battery, NFPA says the alarm is at end of life and must be replaced.
Replacement alarms and batteries:
Kidde 20SD10 (10-year battery) Kidde 20SA10 (hardwired) Energizer MAX 9VReset a battery-only alarm
- Take the alarm off its bracket and remove the battery.
- Press and hold Test (or Test/Silence) for at least 15 seconds. Kidde says it may chirp or sound briefly before going quiet. First Alert says this helps drain leftover power stored in the alarm.
- Put in a fresh battery of the type your manual lists. Close the battery door all the way.
- Put the alarm back on the bracket. Kidde says it will chirp once when the battery connects, and shouldn't chirp after that.
- Press Test to confirm it works.
Hardwired alarm? You also have to cut the power first. See hardwired smoke detector chirping.
Check the battery itself
- Right type, snapped in. Kidde says the battery should be the recommended type and snapped in so it can't shake loose. Disconnect and reconnect it once or twice if contact is poor.
- Fresh date. Kidde suggests a battery with a use-by date four to five years out.
- Door closed. Kidde and First Alert both say to make sure the battery door is fully closed.
When to replace instead
NFPA says chirping that continues after a battery change means the unit is at end of life. Smoke alarms must be replaced 10 years after the manufacturing date. See how to find the date.
How we work: reset steps come from Kidde and First Alert support pages. The replacement rule comes from NFPA. Sources are listed below.
Questions people ask
Why is my smoke detector still chirping after I changed the battery?
Kidde says the alarm can hold the low-battery error after a battery change. Reset it: battery out, hold Test for at least 15 seconds, battery back in.
How long do I hold the test button to reset?
Kidde says at least 15 seconds. First Alert says 15 to 20 seconds.
What if it still chirps after a reset?
Check the battery is snapped in and the door is closed. If it still chirps, NFPA and First Alert say the alarm may be at end of life and should be replaced.
Sources
Last checked Oct 23, 2026. If an alarm may be real, get out first. Only qualified electricians should install hardwired smoke alarms, NFPA says. Turn off the breaker before taking down a hardwired unit.
