Testing and Changing Your Fire Alarm Battery
The National Fire Protection Association (NFPA) recommends changing the batteries in your smoke alarm every 6 months.
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.