Smoke Detector Battery Replacement Time · 6 January 2018

I wonder why it is that the smoke detector battery low indicator (a harsh beep about every thirty seconds or so) always goes off in the middle of the night. Either right after you are settled in and are in that perfect REM state or a couple hours before you get that right amount of sleep.

We usually change out the batteries in our smoke detectors each year. If we remember, right around the time we go off daylight savings time. But if not, right after that annoying battery low indicator tells us that we should have replaced the batteries going off daylight savings time. Which of course happens during the middle of the night. It is an odd phenomenon. That little noise does not interrupt the daylight or evening activities. Only being in dreamland.

It is an odd sound too. That little electronic chirp goes off every thirty seconds to a minute. I have never timed it because I am trying to wake up enough to figure out which one of the sensors is the one chirping. I listen right below one of the sensors. Chirp. Then, I move below the next one. Chirp. Then, I move below the next one. Chirp. Eventually, I figure out which one is the loudest when I am next to it and replace its battery. Or this last time, I just removed the sensor from its mount. I was confident that the other ones in the vicinity would be enough to cover for the missing one until I replaced the battery in the morning.

I figured out this latest routine after the previous time. That time, I changed the battery, then went back to bed only to hear the chirp, chirp, chirp again ten minutes after I had fallen asleep again. I did that routine three times before finally figuring out that I had replaced the battery in the wrong sensor. Or maybe that was the time before. Anyway, it was one of the last two times and the other of those, I had to go through several batteries until I finally found one that worked.

(Incidentally, I tested the battery I removed the other day and found that it is still perfectly good. Unfortunately, I do not have any other non-critical items that use nine-volt batteries or I would use all those perfectly good ones that we remove from smoke detectors in those items. I am not sure exactly why those detectors need to have pristine batteries, but that is okay. I am happy to change them. I just wish it was not always in the middle of the night.)

One of the strangest things about the chirping is that it does not just stop when the battery is removed. It almost always confuses me and makes me wonder if I got the right detector. This time, I almost went through the discovery routine again, but instead just listened closely to make sure I had the right detector. But instead of putting it up to my ear like a dunderhead (which just means that I did that before), I went to a place where no other sensors were and made sure I had the right one. Then, I remembered that there must be a capacitor storing charge and so I pressed the test button and heard the death knell of a digital cricket. Chirrrr… It made me feel good that I could remember something technical in my sleep stupor.

At any rate, I replaced the battery. Which ended the saga of the smoke detectors. But not the wondering. I am sure there are many other unexplained phenomena that could be discussed by experts in a thoughtful forum, but I could not think of any more maddening than why the smoke detector batteries always seem to fail in the middle of the night.

Chirp. Wait for it. Chirp.

All I know about the phenomenon is that regardless of how diligent I am about replacing those smoke detector batteries, one will surely fail. And when it does and that battery indicator starts chirping, I know it will be in the middle of the night.

© 2018 Michael T. Miyoshi

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