I had a smoke detector start chirping last night, it drained the back-up battery. I do not change the batteries every six months because that rule is for battery as primary power and they warn me that they are low.

My real observation is that, in the 10 years we have lived here, the low battery chirping has only ever started at night - between mid-night and 5am.

We are here all the time so it is not like we wouldn't hear it if chirping started during the day. They are loud and easy to hear. We are not missing a day-light chirp.

I asked my wife and she said, it was the same in our last two homes as well.

Does anyone have the answer (actual or theory) as to why they only chirp at night? My wife has a theory, I will share it once a few replies start coming in.

Also, are we the only family to experience such statistical improbability or does it happen in other people's homes as well?

 

I have had smoke alarms to chirp day and night, but I certainly remember the ones that start at night.

As to why they might be more inclined to chirp at night, my first thought is that the darkness makes them more sensitive, but that's just a guess.

PS Mine make the most noise when the wife is cooking. (She likes to cook on high.)

 

Smoke detectors get lonely at night?
Mine always fail in the day time. Maybe that "statistically" balances out your experience.

 

Temperature makes a difference with battery voltages. My 2¢.

 

Bill had the same guess as my wife. She always likes cool bedrooms for sleeping (summer or winter).