We built our house about 5 years ago, and as per the then building code we had smoke detectors put in every bedroom and in the hallways. We bought fairly run-of-the-mill detectors and I have been diligent in changing the batteries.
It’s time again to swap out the batteries and I just noticed that they are wired into the house’s AC power. I guess the idea is that they can rely on AC power when it’s available, but if the AC goes down, which happens now and then, the batteries will be available.
If the batteries get low the units start to beep loudly so I know to immediately change the battery.
So what’s the point of having them connected to AC? It’s not like there’s a trickle charge keeping the batteries fresh, and they make such a racket when the batteries get low that you would be hard pressed to ignore it.
So what value does having them tied into the house power add? There must be a good reason.