At about 3am this morning, one of my smoke detectors started to give off a chirp -- the 'maybe my battery is dead, maybe I'm dirty' chirp.

We managed to more or less sleep through it. By the time we got up in the morning, no more chirps. I'm sure it's waiting for us to be fast asleep again.

I've been through this before. These are all, by the way, wired detectors. it's their backup batteries that they complain of.

A few weeks ago, in the hopes of heading all of this off, I double-checked that all the batteries were recent, and I replaced all the remaining 10-year-old detectors with new ones.


3:30AM this morning. Beep *Beep*

Take a walk around. It is not evident which one is making the noise. Reach a conclusion. Pull one down. Back to bed.

A few moments later: Beep *Beep*

Out of bed again, but it refuses to beep while I'm standing there.

There are not alarm beeps, these are battery beeps.

Turn up the thermostats to daytime. Beeping stops.

Any suggestions?

  • What brand and model? BRK is famous for this problem. – Bryce Aug 10 '12 at 5:44

I had this problem for awhile with my recently installed hardwired detectors. At first I started replacing the batteries figuring maybe the ones included in the box were old (who knows how long they were sitting on the shelf at the store?). Then it kept happening even on some of the detectors that I had already replaced the battery with a fresh one so I stopped replacing the batteries but I would disconnect the hardwire, reset the alarm and re-attach it. That usually would stop it for awhile but a couple days later it kept happening, so I was repeating the procedure and I saw a little spider run across the inside of the alarm. My theory is I have these little spiders were running around inside the alarm. So now I just take them off the ceiling and blow real hard inside to try and get anything out that might be inside.


Watch the LED on the detector; the blink pattern can tell you what the problem is (at least on some detectors).


"Turn up the thermostats to daytime. Beeping stops" -> Are you getting condensation inside of the alarm?

  • At 62 degrees? Though the beeping could be the detectors in the garage, which could well get colder. – bmargulies Jan 11 '11 at 14:39
  • @bmargulies, what else changes when you turn up the thermostat?. It may not be 62 degreee inside the alarm if it is old a cold service (e.g. loft hatch door) – Walker Jan 11 '11 at 16:29
  • Most of the detectors are on the second floor ceilings, just below the attic. Some are near a hatch to the attic. Two are in the garage, which is only heated as a byproduct of the oil furnace. – bmargulies Jan 11 '11 at 17:59
  • Voltage drop in the battery due to the cold? – tomfanning Mar 12 '12 at 12:01

I had this SAME problem. It was driving everyone in the house crazy, not to mention a complete waste of batteries. I recently replaced them all with detectors that have 10 year sealed lithium batteries. Well worth it. Here is a link to the one's I bought:




Test the detector. Both using the test button as well as an actual smoke test.

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