If your smoke detector is chirping intermittently for no apparent reason, it's probably time to change the battery. It doesn't matter if a 9-volt battery is the primary power source, or if it's just a backup for emergencies, the detector will chirp to warn users when energy is running low. To ensure that your device is working properly, it's important to know how to access the battery chamber.
Disengage the appropriate circuit breaker to ensure it is safe to remove the smoke detector. This will not be necessary if your smoke detector is strictly battery operated. Take necessary precautions if you have any doubts about your particular model.
Set up the ladder to get close enough to locate the battery chamber. The door is comparable to the shape and size of the 9-volt battery and is usually indicated by a battery symbol or mechanism for accessing the compartment. If you do not see either of these distinguishing features, then the chamber is located on the back of the device.
Remove the device from its fixed location. In general, you will find arrows indicating which direction you need to rotate it for a safe removal. Hard-wired models will have up to three cables you will need to disconnect: white (hot), black (neutral) and green (ground). If you think you can access the battery without detaching the wires, then proceed to the next step. Otherwise, unscrew the plastic connectors and set them aside to continue working on the smoke detector.
Open the battery chamber using the appropriate screwdriver. While some models have a screw in place to keep the chamber door closed, others may have only a clipping mechanism, and you can use the screwdriver to remove the screw or pry open the door. Once the locking mechanism is disengaged, the door will either slide out of the way or swing open on a hinge.
Install the new battery and test that the device is functional before closing the chamber.
Some battery chamber doors will slide open with minimal pressure, while others may require a bit more force.
Take care not to break any of the mechanisms as this could affect the functionality of the device and possibly void any warranty. Change the batteries annually to ensure the safety of yourself and others.