On 08/10/2019 11:20, Dave Plowman (News) wrote:
In article ,
alan_m wrote:
My bell box has a rechargeable battery that is also trickle charged in
my wired system via the alarm panel. My bell box also has red flashing
LEDs so a self contained non-rechargeable battery may not last that long.

The tamper circuit in a bell box is often a spring loaded mechanical
switch which when the box is removed from the wall is activated.

I thought the bell box battery is only there so it will sound if it or the
wiring to it is tampered with. Under other circumstances, the panel
supplies the ringing volts to it - either from mains or its battery.


Self Actuating Bells do not ring when voltage is supplied from the panel.
The 12v from the panel stops them ringing and charges the battery.

When an alarm condition exists the 12V is removed and they bell rings
until it comes back or the battery goes flat or if its a modern one a
timer expires.


Only cheap and nasty DIY alarms need 12V to operate the bell.
If you have one then get rid of it as it takes seconds to cut the wires
and then there is no external bell.

The old fashioned strobes may be powered from the box, mine are, they
take too much power for the battery.

Its not the same 12V that operates the rest of the box.