How Often To Change Smoke Detector Batteries? – Complete Guide

People that don’t know how often to change smoke detector batteries, are often worrying that their detectors might give up someday.

For many years the choice for the battery for smoke detectors has been 9V AAs.

The number of batteries inside a smoke detector could be two or three 9V AAs, which deliver the required current for a predetermined period of time.

The question, however, is how long?

With most models of smoke detectors, the 9V AA batteries last almost an entire year, but each device is different, therefore, its consumption. You need to replace the batteries of your smoke detector before they are completely worn out for better security.

When Do Smoke Detectors Need New Batteries?

With each different smoke detector brand, the alarms may be different but they all have one thing in common. 

These devices are made to secure your house and wouldn’t let you forget the batteries, which will result in inactivity.

Without power, your smoke detector wouldn’t work and will fail to alarm you in case of fire.

When the batteries in your smoke detector start to wear out, before the smoke detector turns off, there will be a period in which you will be notified.

The most common low-battery notification with almost all smoke detectors is a chirping sound every 60 seconds.

When Does The Low-Battery Chirping start?

This alarm will start to “chirp”, way before the batteries completely die, which ensures that you will definitely hear the noise, while the detector still works.

Usually, there are weeks before the batteries completely give up.

You will know that the battery is about to die soon, whenever the chirping becomes more consistent (per 30-40 seconds).

Note: You can’t stop the chirping sound, except if you replace the batteries.

How Long Do Smoke Detector Batteries Last?

According to the National Fire Protection Association (NFPA), the batteries of a smoke detector should be replaced more often than most people think.

For example, a smoke detector that uses 3x 9V AAs should last about 8 months before the batteries die completely.

In turn, the NFPA recommendation for a battery replacement is every 6 months for better security.

However, some smoke detectors, for instance, the ones that use 2x 9V AAs, won’t last as long as 8 months, instead, the dead point will be earlier.

In that regard, battery replacement every 6 months remains the best approximation for almost any type of smoke detector.

Note: The 10-year lithium-powered smoke detectors don’t need a battery replacement, instead, the entire device is replaced every 10 years.

How Often To Change Smoke Detector Batteries?

To answer this question you would check what and how many batteries your smoke detector uses.

The National Fire Protection Association (NFPA) battery replacement recommendation is every 6 months but with smoke detectors that use only 2x 9V AAs, that might not be safe.

Another thing to consider would be the brand, therefore, the quality of your batteries. It’s normal for cheaper batteries to last shorter than more expensive units.

This is why you should follow the below bullets to determine how often you need to change the batteries on your smoke detector.

Smoke Detector Batteries Duration:

Here is how often you should replace the batteries of your smoke detector:

• 2x Cheap 9V batteries – Replace every 3-4 months.
• 2x Expensive 9V batteries – Replace every 6 months.
• 3x Cheap 9V batteries – Replace every 4-5 months.
• 3x Expensive 9V batteries – Replace every 6 months.

The conclusion is simple. If you’re using cheaper batteries the safe period to replace the batteries is shorter than with more expensive units.

The recommendation here would be to go with the long-lasting AAs even if they are a bit more expensive.

Remember that the bullets above are meant to ensure that the batteries would be replaced before the “chirp” sound starts.

In case you’re going away for a longer period, you don’t want to miss the chirping and your detector turning OFF.

Note: With cheaper batteries, there is always a possibility for them to wear-out quicker than expected.

Best Replacement Batteries For Smoke Detectors

The best batteries you can purchase for your smoke detector are always the more expensive ones.

With batteries, it’s well-known that the more expensive the battery is the more it lasts.

Let’s say that your smoke detector uses 3x 9V AA batteries. The average price of 1 good quality battery is about $3,90 at the time of writing.

You can always find way cheaper batteries, but the time before the chirping sound of your smoke detector starts decreases with every cent you save.

How Much A Battery Replacement Cost?

The average cost to replace your smoke detector batteries is about $10, where you’ll most likely receive 4x batteries.

You’ll have one extra for another suitable piece of tech in your home.

Tip: Never replace your smoke detector batteries with already used 9V AAs, instead buy cheaper but new batteries.

How Often To Replace Wired Smoke Detectors Batteries

The hardwired smoke detectors do not depend on the battery to function. Instead, they use your electrical system as long as there is active power.

The batteries in this type of smoke detector are meant to power the device whenever there is a power outage.

You might be thinking that since the batteries are not actively in use most of the time, the period that they will last will be longer but that’s not necessarily true.

Even if not in use, whenever the batteries are in touch with the electrical poles, their charge decreases.

• Replace cheap batteries every 4-5 months.
• Replace more expensive batteries every 6-7 months.

This is why, to guarantee that the backup batteries won’t fail when needed, you should replace them at least 3 times a year.

They might be able to last longer, but this is the period that is guaranteed and recommended by NFPA.

How Often To Replace Smoke Detectors?

Now when you know how often to replace the smoke detector batteries, let’s learn more about how often you should replace the entire device.

Every device worms out sooner or later but with smoke detectors, it’s quite important to know when it’s time to replace them.

Smoke Detectors Duration:

You should replace your smoke detector every 10 years to ensure that it won’t fail and put you in any danger.

The thing is that it’s not 10 years of usage, instead, it’s 10 years since the smoke detector was made.

You might have used your detector for only a few years, but amortization is not the only factor, instead, you should focus on its assembly year.

Most smoke detectors have labels telling when the device has been manufactured, which will show you how long you’ve got before you need to replace it.

Note: The smoke detectors will not necessarily fail when the 10-year period expires, but this is where most smoke detectors stop working.

The best and safest interval to replace smoke detector batteries is once every 6 months. Depending on whether you’re using cheap or expensive batteries this period might vary, but once the chirping noise starts to sound once a minute, you will know that it’s time.

Read Next: How to Turn Off Kidde Smoke Alarm?

Last Thoughts:

Now you know how often to change smoke detector batteries and how often to replace the entire device.

Almost any smoke detector has an alarm that will start to sound once the batteries get low, and intensify the “chirping” sound when they are about to die.

However, you never know if you’re going to be home when this alarm appears, so it’s best to replace the batteries prior.