Mains smoke alarms beeping

roundthebend

Sat watching Olympics and one of our smoke alarms suddenly beeps. I run out the room to check and there's no sign of trouble. It stopped after a few beeps.

2 mins later the upstairs one goes, then is joined by the downstairs one. Both stopped. This continues, with an occasionally longer run of beeps.

They've not done it for a longer period now, maybe 5 minutes. The house is definitely not on fire. No odd smells or anything. They've been fine for 9 years, seems odd they'd both act weird on the same night.

Both mains powered, I guess with a battery backup, but I doubt the batteries will have run out at the same time.

TTony

One going off should set the other one off.  So, if one backup battery is failing, and activated the alarm, the other will go off too.

Also, check that the sensors are clean.

Dust, or the tiny little black flies that plague us for a few weeks every summer, can get into the sensor, block it, and trigger the alarm.

Kittyfrisk

Have you been eating lots of curry, lentils, artichokes, baked beans or sprouts recently??

guitarcookie1

Change the battery’s. 

skunkwerx

Might be worth replacing them to be sure all is well. 

Think the industry recommends replacing every 10 years anyway. 

I need to change mine.. theyre only cheap battery jobbies.

vasselmeyer

I have mains powered alarms and they communicate wirelessly with each other. If one backup battery runs out, they all beep. Just change them all in one go for another nine years of peace.

olafgarten

They actually expire as well, so check the date written on them. They might need to be replaced fully.