On 07/10/2019 21:24, Dave Liquorice wrote:
On Mon, 7 Oct 2019 19:38:11 +0100, alan_m wrote:

Um, you do know that the external sounder and strobe are
additionally
powered by a second non-rechargeable battery?

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 bell box is normally powered from the panel to keep rechargeables
charged or flash pretty lights. It also "holds off" the sounder
and/or strobe. If the panel voltage drops to low, the sounder and
strobe trigger and run from the battery in the bell box. Once this is
triggered I'd expct it to run for several minutes before trying to
reset and retrigger if the panel volts are still low/abscent.

Commonly adjustable from 1 minute to 20 minutes (the legal maximum).
Some also limit the number of re-triggers, while more basic ones don't.

You
don't want a scrote to be able to shut up the sounder simply by
feeding it volts from another source...

They can do that, but usually the wiring comes through the wall from
inside the house, so they'd need to be inside or they'd have to pull the
box off the wall or open it first (either of which triggers them
immediately). Far easier and quieter to squirt foam inside.

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.

And hopefully the cover... this should trigger a full tamper alarm
condition. Which may or may not cause the sounder/strobe to be
triggered.

Usually it would directly trigger the sounder/strobe of the bell box,
without needing the alarm panel to signal one and then it'd continue to
run on its internal battery. It would also give a tamper alert at the
panel, which may well no longer have a sounder/strobe connected, but as
its going off anyway, that doesn't matter.

SteveW