smoke alarm problems

[tigwig]

At 5.20 this morning to my delight my mains operated smoke alarms started bleeping intermittently. We managed to disconnect them from the ceiling and take out the battery to find that they still bleeped even when they had no power to them at all! How is this possible? It was definitely them bleeping cos I held them to my ear, in the end I went outside in my pyjamas and put them in the boot of the car! Do you think they were bleeping because the batteries needed replacing? Our house is 2.5 years old and obviously the battery will have only been used on the odd occassion there was a power cut because the rest of the time it they were powered through the house electricity.

[leighb]

yes it is the battery that needs replacing, when you have fitted the new battery you must activate the alarm with the test button to reset it.

hope this helps

[tigwig]

thanks leighb I have bought new batteries and will fit them back up tonight but I didn't realise the batteries would need replacing when it is operated by the main electricity supply. also do you have any idea why it still bleeped even after it was totally disconnected and battery removed?!

[Whickerman]

sounds like a design feature - 'better safe than sorry' kind of thing, whereby a mains failure could be caused by a fire, so the alarm is supplied with a hidden power source that ensures when the power fails that the alarm triggers?

[gina32]

yes it is like whickerman said, the same thing happened to my dads and the electirican told him they are made that way for safety

[Disco Fever]

All correct there is a capacitor built in for this kind of thing so if you remove the detector from the ceiling and then remove the battery it will bleep for a short time to remind you of being guilty of removing it from a place where it should be to protect you. When you've installed new batteries blow out as much dust and crap you can as this can also help in detecting smoke better....

[Thunderchild]

possibly the battery was low and it was a low battery warning its not so mysterious that they kept bleeping once disconected if the battery was still in all you had to do was remove the battery