To change batteries in a smoke detector, remove the plating, take out the old battery, and place a new battery in the compartment. Most smoke detector batteries accept 9-volt batteries.Continue Reading
Detach the plate of the smoke detector by twisting it.
Remove the old battery from the compartment.
Place the new battery in the compartment, and ensure that the plus and negative terminals are properly aligned. Place the cover on the unit.
Make sure the detector is working by pressing the button on the unit to hear a beeping sound.