How to Change the Back Up Battery in a Fire Smoke Detector

There are two types of smoke detectors: battery-powered and hard-wired. A battery-powered smoke detector receives all of its power from a battery. A hard-wired smoke detector is powered by your home's electrical system, but contains a battery as a backup power source in the event or a power outage. Smoke detectors are designed to alert you when the battery is dying by emitting a chirping sound. Replacing the battery is a task that you do not want to delay, as the safety of your family and home can be dependent on it.

Things You'll Need

9-volt battery

Instructions

- 1
  Go to your main electrical box and turn off the circuit that powers the smoke detector.
- 2
  Go to the location of the smoke detector. Turn the smoke detector counter-clockwise to detach it and slowly lower it.
- 3
  Disconnect the power plug from the back of the alarm.
- 4
  Lift the battery from the pocket and detach it from the battery connector. If there is a battery compartment door, remove the door then disconnect the battery.
- 5
  Connect the new 9-volt battery to the battery connector.
- 6
  Push the battery back into the battery compartment, replacing the door if there is one.
- 7
  Re-connect the power plug to the back of the alarm.
- 8
  Place the smoke detector against the mounting plate and rotate it clockwise until it locks into place.
- 9
  Restore the power to the smoke detector at the main electrical box.
- 10
  Test the smoke detector by pushing the test button, which is located on the detector.

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