On 07/10/2019 11:09, Dave Plowman (News) wrote:
In article ,
alan_m wrote:
On 07/10/2019 05:30, Andy Burns wrote:
Just had a power cut (70 minutes not too bad a fix time for an 11kV
fault I suppose)

OK, I did have to get up to silence the UPS (also shut down a couple of
unnecessary PCs while at it to extend runtime)

But most annoying is the 15 minutes of alarms sounding due to failed
batteries, then sounding again for another 15 minutes when the power
comes back ...

People seem to think this is normal/acceptable ...

No, that's why I change my battery in my alarm every 3 years.

Crikey. A decent SLA in such a friendly environment should last a lot
longer than that. Got 11 years out of one car battery.


The problem in alarm panels is the battery is never cycled - just
trickle charged 100% of the time. After a number of years the battery
still has the correct terminal voltage but cannot provide the
instantaneous backup power when the mains fails. As a result there is a
glitch in the power to the alarm panel and the alarm is triggered. The
backup batteries still can supply enough power for the sounders/lights
for a long time etc. Checking the battery afterwards will again show the
correct terminal voltage. You may only see the problem for the first
time is when the mains power fails.

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