When Should I Change My Smoke Alarm Batteries?

Nov 3 2021

This is part of our ongoing series on the basics of owning a home.

Don’t wait for the chirp.

Like opening your mail or cleaning out your coffee pot, changing your smoke alarm batteries tends to land on the list of things you’ll get to one day. But it’s a pretty important task (as is opening your mail, heh heh) and it’s never too late to get in the habit.

One way to remember is with the simple phrase, “change your clocks, change your batteries.” When you turn the clocks back after Daylight Saving Time ends in the fall, switch out the batteries in your smoke alarms.

Yep, just once a year — not so bad, right? But it’s a good idea to test them once a month, too. It’ll give you peace of mind that they’re in good working condition.

But what about your other questions, like which batteries are the best to buy, and when should you switch out the alarms themselves? Below is a brief dive into the science of maintaining smoke alarms.

Which batteries do smoke detectors need?

Most use 9-volt alkaline (you know, those rectangular boxes with two prongs at the end?) but some use AA. It’ll be specified in the battery compartments in your smoke alarms, so have a look to be sure.

Can you use rechargeable batteries in a smoke detector?

Using rechargeable batteries in something as important as a smoke alarm isn’t typically advised, since their charge levels aren’t reliable.

Can you use lithium batteries in a smoke detector?

Lithium batteries carry more charge than alkaline so they may last longer, but they tend to be more expensive. Plus, you can throw alkaline batteries away in the trash, but lithiums must be recycled at facilities that accept them.

Do all smoke detectors need batteries?

Yes, but not all can be switched out.

Some smoke alarms come with 10-year tamper-free batteries, meaning the battery compartments cannot be opened and the devices can be used for a decade. Others are hardwired to your home’s electrical system and have backup batteries in case you lose power.

When should you replace your smoke alarms?

The alarms will have expiration dates written on the back, but every 10 years is recommended.


Onto the next home maintenance project?

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