Mains smoke alarms - cheep every few days

[David]

Every few days (I think) one or both of the mains smoke alarms cheep once.

On line search suggests that low battery should cause a regular cheep (already experienced that and changed the battery).

There is also a suggestion that dust could cause a false alarm - but this isn't an alarm, just a single cheep.

Has anyone else experienced this, and worked out what was causing it?

The alarms have been fitted for about 5 years.

Oh, and does everyone change their smoke alarms every 10 years?

Cheers

Dave R

[The Natural Philosopher]

yes

No.

No.

[Chris Hogg]

It's not just to indicate that the alarm is working, is it, a bit like the continuous beeping they have in places like Sellafield?

[alan_m]

End of life warning?

[The Natural Philosopher]

Nope. A bit of reaearch suggests its not a low battery, but it could be dust, or a failing sensor.

I had a long shower with the bathroom door open earlier this year. The bloody lot went off...

They all work...

[Steve Walker]

Ours have produced single, random cheeps as the batteries have got low, only progressing to regular cheeps as the battery deteriorated (it was about a week until we got the time to get new batteries and fit them).

We also had a similar effect with a microchip cat-flap - when it took us days to find the problem, as the sound was very low volume and difficult to locate, sounding like it was in another room, no matter which room we were in.

Not here. The recommendation seems to have come about because some alarms are fitted with 10-year batteries and because sensitivity can change (it usually increases), causing nuisance alarms and prompting people to disconnect the batteries!

As long as ours continue to keep quiet unless the toast has been burned again, I'll trust the test function and not replace them.

SteveW

[tim...]

and keep the user awake all night

great feature (not!)

tim

[ARW]

Assuming that the OP has replaced the batteries with the correct ones I would suggest that a detector has now failed and is not correctly registering the batteries voltage.

As we have no idea of the make and model number of the detectors all we can do is guess.

[Chris Hogg]

Ah, but the OP said it cheeps once, every few days. Hardly enough to keep anyone awake at night.

[Chris Hogg]

Do 'mains smoke alarms' have batteries?

[ARW]

Good question.

Grade D is the minimum requirement these days for interlinked smokes in a new build. These do require some sort of standby back up should the mains fail. This could be in the form of inbuilt capacitors and may not a battery.

Grade E detection systems are mains powered without any form of battery back up. They are frowned upon and possibly illegal to fit even though they may be interlinked.

Grade F are battery operated non interlinked detectors. These are the minimum requirement for all rented properties in England.

[alan_m]

With a bit of research, on some main powered and battery backed up detectors multiple beeping every 40 seconds (rather than once every 40 seconds for low battery) is an end of life indication.

Also if the replacement battery was a rechargeable type the detector may beep during the first few days until fully charged.

With my battery alarms I often get the first signs of a low battery a few times at night when its colder but by morning when perhaps the heating comes on the battery recovers a bit and the beeping stops. I now put a label on the units giving the date when the battery was changed.

[The Natural Philosopher]

yes.

Essentilly on very low trickle charge all the time. AIUI

[Bill Wright]

I have interlinked mains ones that each have battery back up. Last year they all started to do a once-a-day cheep. It turned out that the one in the loft had a faulty battery.

Bill

[ARW]

Not many detectors work with rechargeable batteries.

[tabbypurr]

Almost certainly a dying battery. Battery current output ability depends on temperature, hence it sometimes happens in the night only, at first.

I'm sure they don't

NT

[Brian Gaff]

I don't, but I guess that depends on how they work. The radioactive ones must decay surely?

Do they cheep in unison or just randomly? Brian

[Brian Gaff]

It would be very annoying if you had quite a few and they all did it at different times though. Brian

[Andy Burns]

Yes, but with a half-life of 432 years

[Tim+]

Combination of low battery and low temperature usually. Typically they cheep sometime during the night when your just half aware of it. When the temperature rises during the day they cease cheeping as the battery voltage rises above the alert threshold.

Then you forget all about it until the next cold night. ;-)

Tim