In my experience its the rechargeable battery inside the thing needs replacing.
Can I ask a dumb question please, having trouble opening the smoke alarm, before I go at it further you definitely do not need to disconnect the mains power in order to change the battery do you ?
Generally there is NOT mains power going to smoke alarm.
There's power going to mine; with battery back up.
we have a battery type alarm (no connection to electricity). before going on hols recently i checked and got the usual beep. However when away the battery was obviously low and beeped continually so much so my helpful neighbour heard the noise. Was puzzled and rang my son who took out the battery. My query is there anyway of knowing if a battery is going to sendout the beeping warning so as to avoid what happened to me
Thanks Sparkeite, it's the mains alarm with battery back-up, we flicked the trip switch but for the life of us could not get the cover off the alarm! Nearly took the whole unit off the ceiling a few times. Anyhoo, when flicked the trip switch back it gas stopped the beeping temporarily so that's good, will get us by until we can get out from this snow to get some batteries!