Smoke Alarm Keeps Chirping After a New Battery — What It Means

General information only. This page covers battery-powered smoke alarms. For alarms wired into your home's electrical system, see the hardwired section below.

First, know the two sounds

A smoke alarm makes two very different sounds. They mean very different things:

• Three loud beeps, again and again — beep, beep, beep: This means smoke or fire. Get out, call 9-1-1, and stay out.
• One short chirp every 30 or 60 seconds: This means the battery is low and must be changed.

This page is about the second sound — the slow chirp. If you hear the loud beeps, stop reading and get outside.

In a fire, you may have as little as 2 minutes to escape safely. That is why a chirping alarm should never just be ignored or unplugged.

Why it still chirps with a new battery

Smoke alarms do not last forever. All smoke alarms must be replaced 10 years after the date they were made — the manufacturing date.

When an alarm reaches the end of its life, it keeps chirping even with a fresh battery in it. The chirp is the alarm telling you that the alarm itself is worn out, not the battery.

So if you changed the battery and the chirp came back, the fix is a new alarm, not another battery.

How to check the date

Take the alarm down from the ceiling or wall and look for the date it was made.

• If that date was 10 years ago or more, replace the whole alarm.
• If the alarm is less than 10 years old, put it back up and test it, as described below.

Learn the sounds of your own alarm by checking its user guide, or by searching for the brand and model online. Different alarms can use their sounds in slightly different ways.

Safe checks you can do

These are the simple checks the fire safety guides describe. They need no tools:

• Test once a month. Push the test button once. You should hear the loud beep, beep, beep sound. That means the alarm is working.
• If the test button makes no sound, change the battery. If the alarm is over 10 years old, replace the entire unit instead.
• Change replaceable batteries at least once a year. Alarms that run on a 9-volt battery need a fresh battery at least once every year, and the whole alarm replaced every 10 years.
• Keep it clean the maker's way. Follow the manufacturer's instructions for cleaning to keep the alarm working properly. Those instructions come in the package or can be found online.
• Never take the battery out to stop noise while cooking. If an alarm sounds while you are cooking, open a window or door and press the “hush” button, or wave a towel at the alarm to clear the air. Taking the battery out can be a deadly mistake. A smoke alarm with a dead or missing battery is the same as having no smoke alarm at all.

Hardwired alarms — when to call an electrician

Some alarms get their power from your home's electrical system. These are called hardwired alarms. They usually have a backup battery too.

For a hardwired alarm, the safe home care is the same simple list: test it once a month, replace the backup battery at least once every year, and replace the entire alarm every 10 years.

Do not do wiring work yourself. Only qualified electricians should install hardwired smoke alarms. If a hardwired alarm keeps chirping after a fresh backup battery, or it needs to be replaced, call a licensed electrician to do the work.

Where alarms belong

While you are replacing an old alarm, it is a good time to check that you have alarms in the right places:

• Inside every bedroom and sleeping area, and outside each sleeping area, such as in a hallway.
• On every level of the home, including the basement.
• On the ceiling or high on a wall.
• At least 10 feet (3 meters) from the stove, to cut down on false alarms while cooking. Do not put smoke alarms in the kitchen or bathrooms.
• Check the manufacturer's instructions for the best place for your alarm.

Choose an alarm that is listed with a nationally recognized testing laboratory. That means it has met certain standards for protection. Alarms that use a battery you change each year, and 10-year alarms you replace whole at the end of 10 years, will both provide protection.

Some fire departments offer reduced-price, or even free, smoke alarms, and some will install battery-operated alarms in your home at no cost. You can ask your local fire department's nonemergency phone number for more information.