Every floor of your house should have a working smoke detector installed. Install your smoke detector high up on the wall or on the ceiling. Make sure to test your smoke detector once per month to be sure that it works. Open your smoke detector and change the batteries every six months, and replace the entire smoke detector every 10 years.
Remove the smoke detector from the wall or ceiling. There will be a circular mounting bracket left behind. Some smoke detector models will pull right off the bracket; others you will need to twist counterclockwise to release.
Locate the battery compartment door. This will normally be on the back of the smoke detector. Some smoke detectors will not have a door, but you will notice tabs on either side of the detector.
Insert the tip of a small screwdriver into the lip of the battery door. Some doors will be held shut by a screw. If this is the case, simply use the screwdriver to remove the screw and open the door. If your smoke detector has tabs on either side, push these tabs in and lift up to expose the battery.