Why is my smoke detector chirping with a new battery?

The alarm may be at the end of its life (most last 10 years), the battery may be the wrong type, or a hardwired alarm may need a reset after a power outage. Check the manufacture date and replace the alarm if it is around 10 years old.

How often should you replace smoke detectors?

Every 10 years, according to the NFPA. Carbon monoxide alarms usually need replacing every 5 to 10 years, as stated by the manufacturer.

How often should you test smoke alarms?

At least once a month, using the test button.

Smoke detector chirping? What it means and how to fix it

A single chirp every minute, usually at 3 a.m. "Smoke detector beeping" and "smoke detector battery" are among the most searched home safety questions in the US. Here is how to find the cause and fix it for good.

What the sound means

Sound	Likely cause	What to do
One short chirp every 30 to 60 seconds	Low battery	Replace the battery, or the whole alarm if it has a sealed 10-year battery
Chirping with a fresh battery	End of life (often 10 years) or wrong battery	Check the manufacture date; replace the alarm
Chirp after a power outage (hardwired)	Backup battery low or error stored in memory	Replace the backup battery and reset the alarm
Three long beeps, pause, repeat	Smoke detected	Get out, stay out, call 911
Four beeps, pause, repeat (CO alarm)	Carbon monoxide detected	Get to fresh air and call 911

Patterns vary by brand. The label on the back of the alarm or the manual explains each signal.

How to stop a chirping smoke detector

Find the right alarm. The chirp can echo; stand under each alarm until you hear which one it is.
Check the type. If the alarm says it has a sealed 10-year battery, the battery cannot be replaced: replace the entire alarm.
Replace the battery with the exact type listed on the alarm. NFPA notes that using a different battery can stop the alarm from working properly.
Reset it: press and hold the test button for 15 to 20 seconds. For hardwired alarms, turn off the breaker, remove the alarm, disconnect it, replace the backup battery, and hold the test button before reconnecting.
Test it: press the test button until the alarm sounds.
Still chirping? Check the manufacture date on the back. If it is close to or over 10 years old, replace it.

Never remove the battery and leave the alarm empty to stop the noise. Most home fire deaths happen in homes without working smoke alarms.

Why it chirps at night

Batteries lose voltage when the air cools down. Homes are usually coolest between 2 and 6 a.m., so a weak battery crosses the low-power threshold at night. It is a real warning, not a malfunction.

How to maintain your smoke alarms

These are the National Fire Protection Association (NFPA) recommendations:

Test every alarm once a month with the test button.
Replace batteries at least once a year in alarms that use replaceable batteries, and right away when they chirp. Many people do it when the clocks change in the fall.
Replace every smoke alarm after 10 years, even if it seems to work. Sensors degrade over time.
Clean them according to the manufacturer, usually with a vacuum brush attachment.
Replace CO alarms as the manufacturer instructs, usually every 5 to 10 years.

Where to install smoke alarms

NFPA recommends an alarm:

in every bedroom;
outside each sleeping area;
on every level of the home, including the basement.

Interconnected alarms are best: when one sounds, they all sound. Install CO alarms outside each sleeping area and on every level, away from fuel-burning appliances. Local codes may require more, so check your state and city rules.

Renters and landlords

Rules depend on your state. In many states the landlord must install working alarms and the tenant must test them and replace batteries during the tenancy. Oregon, for example, requires tenants to test alarms at least every six months and to report problems in writing.