Smoke alarms are only as good as the battery that powers them unless you hard-wire them into the home. Even hard-wired smoke alarms have a battery as a backup power system. You should test your smoke alarm at least once a month to ensure the battery is good. There is a small button on the unit you press with your finger to test. If you test the unit and it does not sound or if your wired smoke alarm beeps periodically, it is time to change the battery. Removing and changing a smoke alarm battery is generally the same among the many different manufacturers.
Position a step stool under the smoke detector so you can reach it comfortably. Grab the smoke alarm and turn it counterclockwise to disengage it from the base. Some units have locking tabs that you press in with your fingers to disengage them from the base.
Lower the smoke alarm slowly. Some smoke alarms connect to wiring coming from the ceiling. If you have wires, look for the small plastic connector plugging into the smoke detector. Pull the connector out of the smoke detector.
Find the battery compartment door on the smoke detector. It is either on the side of the unit or on the top or bottom. Side mounted battery compartments require you pushing them in with your finger to disengage a spring. Snap-on battery compartments require you prying the cover off with a small flathead screwdriver.
Remove the old battery from the battery connector with your fingers.Insert a new battery into the connector. The battery connects in only one way. If you have a unit that plugs into ceiling wires, the unit may sound when you remove the battery.
Plug the wire connector into the back of the unit, if yours uses the ceiling wires. Reattach the unit to the base either by pushing it into the base until it snaps into position or turning it clockwise until it locks.
Some smoke detectors may take a smaller battery or AA batteries. Replace with the same size battery.