Everything You Need to Know About Replacing a Smoke Detector Battery

smoke detector battery

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If you are like many homeowners, you pay little attention to your smoke detector's battery. You installed the smoke detector, pressed the test button once, then forgot about it until it started chirping at you as a battery replacement reminder some months later. Yet the battery in your smoke detector is the vital link between this sophisticated electronic item and the safety of you and your family. Without that battery, the smoke detector is useless and you and your home are not safe.

Why You Need to Replace Your Smoke Detector Battery

Studies prove that smoke detectors save lives. Homes with smoke detectors are safer than homes with malfunctioning or non-existent smoke detectors. Dead batteries are the cause of many of these malfunctioning smoke detectors.

In a four-year study, 40 percent of home fire fatalities occurred in homes without smoke detectors. 17 percent of all fatalities happened in homes that had smoke detectors, but those detectors were not working. Of those failed smoke detectors, about 25 percent were caused by dead batteries.

Statistics apply not just to other people but you, as well. If you keep your smoke detector up and running, you have double the chance of staying alive in the event of a fire than if your smoke detector is down.

But the other interesting point about smoke detector batteries is that they supply power both for occasional services such as alarms, chirps, and blinking lights and for constant services. What many people may not realize is that a smoke detector is running all the time. With an ionization smoke detector, the battery supplies electricity to positive and negative electrodes. Ions charged by the battery are constantly moving between the two plates. With photoelectric smoke alarms, an LED light is cast onto a photoelectric sensor.

If your smoke detector does not have a fresh battery, it cannot supply power for these constant services.

How Often to Replace a Smoke Detector Battery

You should always replace your smoke detector battery immediately after it emits a warning beep or chirp indicating that the battery is low.

In addition, most smoke detector manufacturers recommend that you replace the battery at least one time per year. To give yourself an even wider margin of safety, you should replace the battery two times per year, with the changes evenly spaced out.

If you live in an area that uses daylight savings time, this can be used as a reminder for replacing the battery. Within one year, replace the battery once when switching to daylight savings time, then replace it a second time when switching back to standard time.

How to Replace Most Smoke Detector Batteries

Smoke detectors' battery replacement operations vary, but there are some common features:

  1. You will need to access the smoke detector with a ladder or chair as most are ceiling-mounted (though a few may be mounted high on a wall).
  2. Most smoke detectors must be removed from the ceiling to replace the battery, though some do have a front-loading door. Twist the detector counter-clockwise. The smoke detector should release, with the mounting plate remaining on the ceiling. Some smoke detectors will have a tamper-resistant feature to prevent children from removing the device. Disengage with the locking pin.
  3. Replace the battery as directed by the smoke detector instructions.
  4. Place the smoke detector back in the mounting bracket and slightly twist clockwise. The smoke detector should engage.
  5. Test the smoke detector with the testing button usually located on the face of the unit.

How to Replace a Smoke Detector Hardwired With a Backup Battery

This type of smoke detector receives household current, with an onboard battery used as a backup in the event of power failure.

  1. At your home's electrical service panel, turn off the household power to the circuit supplying the smoke detector by switching off the proper circuit breaker.
  2. Use a ladder or chair to access the smoke detector.
  3. Remove the smoke detector from the mounting base by turning the smoke detector counter-clockwise. If the smoke detector does not disengage, it may because of a tamper-resistant mounting bracket. Disengage by pushing the locking pin into the unit.
  4. Do not immediately try to pull off the smoke detector as it is connected with a wiring harness. Tilt the smoke detector to the side and locate the wire connector leading into the unit. Unplug the wire from the smoke detector or mounting base, as applicable
  5. Replace the smoke detector's battery at the door usually located either on the side or the back of the unit.
  6. Reconnect the wiring harness to the unit or base, fit the unit onto the base and turn the unit clockwise engage it on the base.
  7. Turn on the circuit breaker to restore household power to the detector's circuit.
  8. Test the smoke detector with the test button.

About 10-Year Lithium-Ion Smoke Detector Batteries

10-year sealed lithium-ion smoke detectors' batteries are never replaced. Instead, dispose of the entire unit responsibly and replace with a new unit.