How to replace battery in first alert smoke detector 9120b

How Often Should You Change the Batteries in Your Smoke Detector?

The smoke detectors s throughout your home help play a crucial role in keeping you and your family safe by alerting you to potential dangers. However,  smoke alarms are no use if they do not have working batteries. It is important that you take the time to check and test home smoke detectors often and change the batteries  to ensure they are working properly.

What Smoke Alarm Do You Have?

The National Fire Protection Association (NFPA) recommends changing the batteries in your smoke alarm every 6 months. At First Alert, we offer 10-year smoke alarms that have a built-in 10-year battery, which eliminates the need for battery replacements for the life of the detectors. We also offer hardwire fire alarms with a battery backup, for protection during power outages.

Testing and Changing Your Fire Alarm Battery

It is recommended you test your detectors at least once a month to ensure they are working properly. If your smoke alarms are powered by a nine-volt battery, the battery should be replaced every 6 months, while the alarm itself should be replaced once every 10 years. For 10-year lithium-powered fire detectors, you won’t need to replace the battery. Instead, the entire alarm should be replaced after 10 years have passed from the manufacture date on the back of the alarm. If your alarm is hardwired into your home’s electrical system, replace the backup battery at least every 6 months and replace the smoke alarm itself once every 10 years.

Signs You Need to Replace the Batteries In Your Smoke Detector

You’ll likely notice a high-pitched chirping noise coming from your fire alarm if the batteries need to be replaced. It is best to be proactive and change the batteries in your smoke detectors before the low battery chirp  occurs. When you change the batteries in one fire alarm, make sure you change the batteries in the rest of the detectors in your home as well. A helpful reminder to check your smoke alarms and change the batteries every 6 months is Daylight Saving Time. Check your fire detectors when you change your clocks.

Installing smoke detectors will help keep you and your family safe. Browse our website to learn more about fire alarms or other fire-related equipment such as fire escape ladders, fire extinguishers, and more!

Top positive review

5.0 out of 5 starsGood smoke alarms, but sometimes they need a hard reset to fix the false low battery alert

Reviewed in the United States 🇺🇸 on November 11, 2018

I bought a couple of these to replace my old detectors three years ago. I was hoping they wouldn't give me grief when it was time to replace the batteries- the old ones were a little finicky and would still chirp even with brand-new batteries.

At 12AM this morning one of these started chirping even though it's battery measured 9.62V. I replaced the battery, and first thing this morning I checked the voltage of the battery in my other detector, which was still working fine, and it was at 9.23V. I did some searching and found that sometimes a chirping smoke alarm needs a hard reset to clear the microprocessor of errors that can cause a false low-battery alert.

In order to do this you need to disconnect the unit from AC power, remove the battery, then hold the test button for 15 seconds(it's also a good idea to mute the siren by covering it with your thumb.) You'll hear the alarm sound, then taper off to silence.

After doing the reset on the faulty unit I plugged it back in, installed the battery that measured 9.23V, and it's been working fine for several hours- so if you're having trouble with an alarm that still chirps every few minutes even though the battery is good, a hard reset may be the solution.

• Remove the alarm by rotating it counter clockwise in the mount.

• The alarm should fall off once rotated enough. The cable should be the only thing holding it in place if done correctly.

• Unplug the cable from the alarm.

• Press down on the catch on the top left of the alarm to open the battery compartment.

• Remove the battery and dispose of it properly.

• Replace the old battery with a new 9V battery and close the compartment.

• You should hear a click to know that the compartment is secured.

• Line up the holes of the cable on the mount with the pins on the alarm.

• Reconnect the cable on the mount to that on the alarm.

• It should insert itself with minimal force.

• Press the alarm into the mount.

• Rotate the alarm clockwise until it does not turn anymore. This makes sure the alarm is secured.

How do you open a First Alert battery compartment?