Its not the consistent “chirp” that occurs when an individual battery is dying. About once a day or two, several will go off, like they have detected smoke. But it lasts about 2 seconds, and then stops.
I don’t know if all of them are going off, but since they are wired together, I suspect they all are. Certainly its several of them.
I’ll look into replacing all of them, but I’m curious why they just ‘go off’ unlike the familiar dead battery chirp of a single one.
our wired together smoke alarms all alert simultaneously when one of their batteries need replacing. I swap all three at the same time. I find that they are nearly all depleted the same amount anyway. Still useful for powering other things.
Could be a bug or small dust bunny, especially if it’s a photoelectric detector (basically just shining a light beam onto a sensor across an air gap). That’s happened with the detector in the hall outside my bedroom. It’s above a light that’s on 24/7, so spiders and moths like to get in there. A quick blast of compressed air usually takes care of it.
How old are they? Had a similar problem with detectors well past their 10 year lifetime.
They probably need replacing, although it may be just one of them. Sometimes they go bad before their 10 year lifetime. This happened to us recently, one smoke detector just went bad and would randomly go off. We swapped it out and the alarms stopped.
Insects are a common problem. Another source of problems is when the back(s) of the device(s) are not properly sealed. For example, a unit might be mounted to an electrical box in the ceiling and the box is exposed to the attic. Changes in air pressure between the attic and the interior of the house will cause air (often loaded with dust) to move through the device. Many manufacturers provide a small piece of foam to seal the entry point(s) of the device. Make sure that there are no openings in the electrical box, such as unused knockouts. One indicator of the problem is removing the device and seeing dust deposits in the box or on the backplate of the device.
Additional pedantry: Good mix of info in previous posts. The devices mentioned by the OP are “smoke alarms” intended for household use. They are listed under ANSI/UL Standard 217. Smoke alarms must be replaced every ten years. “Smoke detectors” are system devices and are listed under ANSI/UL Standard 268. Smoke detectors do NOT have to be replaced every ten years. They may remain in service as long as they continue to pass the calibrated test described in the manufacturer’s installation instructions. Smoke detectors are normally used in commercial installations, but may be used in household installations when an appropriate fire alarm system (control unit, primary and secondary power sources, and notification appliances) is provided.
As @Marvin_the_Martian said, these gadgets don’t last forever. They need to be replaced every few years. It’s cheaper than having your house burn down.
Yeah, some alarms do that when they get old. Drove us nuts.
About two years after having a loft extension on her house, my daughter started hearing that ‘chirp’. Adding another floor meant that they had fully mains-wired alarms, so no batteries to die.
It drove them mad for a while until they found that the builders had discarded their old battery alarm in an unused roof space.
In the US hardwired (mains-wired) smoke alarms still need battery backup so they still function if the power goes out - so batteries still need replacement and the alarms will still chirp if you wait too long. If the house has a central alarm system, the smoke alarms may be powered from the alarm panel and have a centralized battery backup there. In this case the alarm system will issue a warning if the battery gets too weak.
Relatively recently hardwired alarms with 10 year batteries have been available. All my smoke alarms have them, so I haven’t had to replace batteries in a chirping detector for a few years.
So they do here, but the batteries are rechargeable so replacement periods are pretty long.