How to change a smoke alarm battery

There are different types of smoke alarms. Some use lithium batteries and last for up to 10 years, but the whole unit needs to be replaced once it expires. Other detectors have interchangeable batteries.

To identify which smoke alarm you have, look at the little light on it. A steady green LED light indicates that your alarm is using AC power (it’s wired to the mains electricity in the home). Battery-operated alarms will have a quick flash every 30–45 seconds.

If you have a battery-operated smoke alarm, remove the smoke detector from its mounting on the ceiling. The method you use will vary depending on which type of smoke detector you have. Most models can be removed by twisting, sliding or clicking a click-into-place bracket. Some models require you to remove a section that covers up the batteries as opposed to removing the entire detector.

Once you’ve safely removed your smoke detector or battery cover, remove and discard the old batteries. Install the new batteries correctly, lining up the negative and positive connections as labelled on your smoke detector.

Close the battery cover and secure the smoke alarm back onto its mounting bracket.

Once you've reattached the smoke detector, do a test run to make sure the batteries are working properly. Locate the test button and press it down for a few seconds to engage the test. If your batteries are working properly, your smoke alarm will let out a sound. If there is no sound, you’ll need to try different batteries or look at resetting the entire alarm. You can do this by pressing down the reset button for 15-20 seconds. Repeat these steps until you hear the alarm make a sound when testing it.