Resolved: Smoke alarm batteries never die during the daytime

The smoke detectors in my house have a nice feature:

They are hardwired using a battery as backup. When the battery gets weak they’ll start beeping. If the battery is removed at this point they will stop beeping. Best feature ever, IMO, as they always start beeping at 2AM and I rarely have spare 9V batteries on hand.

that close to cooking area is bad for nuisance triggering.

We change ours with daylight saving every year, it is a government run campaign and so I have never had batteries go flat on me. Change the time, change the batteries.

Why don’t mine do that? If you remove the battery from mine they still beep. Instead of a ‘low battery’ beep, it’s a ‘no battery’ beep.

How does it beep without a battery? Or do you have wired detectors too?

So I guess the whole “Check your alarm once a week” campaign used when I was in school didn’t work that well.

Also, while the temperature in my house goes down at night, that’s because the central heating barely works. With normal heating, I thought the temperature was supposed to be fairly constant. So I question this as a reason that smoke detectors mostly fail at night.