How Long Do Smoke Detector Batteries Last (Stats & Tips)

Smoke detectors must be in good shape to protect your family from smoke and fires. Regularly changing the batteries is a key part of maintaining them.

Smoke detector batteries can last months or years, depending on the type. For Alkaline batteries, the National Fire Protection Association (NFPA) recommends replacing them every 6 months. In comparison, Lithium batteries can last 5 years and even through the smoke detector’s lifespan. 

The lifespan of Smoke Detector Batteries

Smoke detectors generally use two kinds of batteries: Alkaline and Lithium Batteries.

Generally, Alkaline batteries have shorter lifespans than Lithium ones. Alkaline batteries can last for months – up to a full year, while Lithium batteries can easily last for years. These two have different lifespans due to each battery’s unique material and capacity.

9-Volt Smoke Detector Batteries

A replaceable 9-volt smoke detector battery can last 12 to 18 months, but the National Fire Protection Association (NFPA) recommends changing them every 6 months.

hands holding an alkaline duracell battery
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Most smoke detectors use single-use 9-volt alkaline batteries that must be replaced once they run out. Realistically, these batteries easily last for a year of use since smoke detectors don’t use a lot of power. However, single-use batteries can deteriorate over time— some may even corrode or leak.

The NFPA recommends replacing Alkaline batteries every 6 months to retain the smoke detector’s functionality and prevent safety issues from happening.

Lithium Smoke Detector Batteries

Single-use Lithium battery smoke detectors generally last around 5 years, while rechargeable ones last for the device’s entire lifespan.

Lithium batteries can consistently discharge power without being charged for long periods. They’re built to last for years and not lose strength during that time, making them an excellent choice for fire alarms. If the Lithium cells are rechargeable, you can keep recharging and reusing them until it’s time to replace the battery detector.

a lithium battery sealed in a smoke detector
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It’s a different matter if Lithium batteries are sealed within the smoke detector.

Sealed Lithium batteries share the same lifespan as the smoke detector.

Smoke detectors that use sealed Lithium batteries are expected to last 7 to 10 years. These come packaged in the battery detector and are integrated into the device. They’re meant to last throughout the full lifespan of the smoke detector.

For these devices, you won’t need to worry about recharging or replacing the battery until it’s time to replace the entire device— making them an ideal choice for rental properties.

Signs That You Should Replace Your Smoke Detector Batteries

a hands wearing a black gloves holding a smoke detector
Video | 2AEnthusiast

Take Alkaline batteries, for example, theoretically, they can last for a year, but it’s better to replace them earlier for safety reasons.

Luckily, knowing when to replace your smoke detector batteries is as easy as looking for these signs:

Chirping or Beeping Sounds

Smoke detectors have a low battery warning that gives off a low chirping or beeping sound.

Unlike the smoke alarm, the low battery warning goes off without detecting any smoke. You’ll typically hear a periodic chirping noise which indicates that a battery replacement is needed as soon as possible.

Failed Smoke Alarm Tests

Smoke detectors have a built-in tester to check whether the device is fully operational.

The smoke alarm test is activated by pressing and holding the test button on the device. After a few seconds, it will emit a loud, siren-like sound until the button is pressed again. If no sound is produced or it sounds weak, the smoke detector is due for a battery replacement.


Classification of Cells or Batteries – University of Washington.

Smoke Alarms – National Fire Protection Association.

Video References


Penguin DIY



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About Alex Robertson

c3c9d43f1f0d14c4b73cb686f2c81c4e?s=90&d=mm&r=gCertifications: B.M.E.
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Hi, I’m Alex! I’m a co-founder, content strategist, and writer and a close friend of our co-owner, Sam Orlovsky. I received my Bachelor of Mechanical Engineering (B.M.E.) degree from Denver, where we studied together. My passion for technical and creative writing has led me to help Sam with this project.

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