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Dead Batteries In Smoke Detectors

Question: I am replacing the batteries in my hardwired smoke detectors every 3 or 4 months. I even purchased the best 9 volt lithium batteries that I could find and even they didn’t last very long. What is the problem?

Answer: Make sure that the breaker for the smoke detectors is in the "ON" position and that it is functioning, or if you have fuses, rather than breakers, make sure that the fuse has not blown.

Batteries installed in hardwired smoke detectors are only meant to power the smoke detectors in the event of power failure. The smoke detector is not designed to be powered by the batteries for an indefinite period of time. If the AC powering the smoke detectors is not working then the batteries end up powering the smoke detector continually and they will have a very limited life – just as you are experiencing.