In message , F
wrote
We've had a couple of power cuts recently (up to two hours) while we
were out and the alarm was set. Neighbours have said that the alarm has
gone off each time the power has come back on. While the power was off
none of the panel lights were lit and when the power came back on and
we reset it 'Day' and both zones were lit.

Is this expected behaviour?

I thought the battery in the control panel and the one in the bell box
were supposed to deal with power cuts. Could it be that one or both of
the batteries needs to be changed?

The alarm is a Scantronic 9448.



When this happened to my alarm it was the battery at fault, even though
it was still giving a 12v reading. The batteries don't last forever and
after a few years should be changed.

I suspect that old batteries don't hold a full charge and while they can
maintain the alarm for a short period whilst the mains is off they drag
down one of the power supply lines when the mains comes back on. This
glitch on the internal supply line triggers the alarm. You can test this
yourself by switching off your mains power at the 'fuse' box for a
couple of minutes.

The battery in the bell is used to sound the alarm when someone cuts the
wires to the main control unit.
--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk