swapping alarm panel battery

[chopper]

Would a 12v 2.1 ah battery be ok to replace a 12v 2.8ah. As I can got get hold of a 2.8 ah one locally

 

[Spoon]

what is your location?
What does the alarm manual say? What make of alarm is it? Someone may have replaced the original battery, which may have been a 2.1ah with a 2.8ah one and thats why I ask.

 

[Silly Sausage]

I would have thought it (2.1Ah) would just last 25% less than the original (2.8Ah)...

 

[Spoon]

I dont want to assume anything Archy. As far as I remember most house alarms use 2.1Ah, but the OP hasnt said what type of alarm system it is. I dont know if the big office alarms need the bigger battery.

 

[tazz]

Excatly Spoon, Every type of alarm has it own standards on battery backup (security, fire etc). With their own standby and duration.
but there is one calculation for all..............B=(QxS)+(AxT)x1.25
B=battery capacity...Q=standby current in mA....S=standby time in hours...A=alarm current in mA....T=alarm duration in hours.
the 1.25 is the correction factor for SLA batteries.
So if the OP uses this calculation, he should know what battery he requires as a minimum.

 

[chopper]

Is just a alarm in a mate's house never heard of brand and cant remember .it began with s .lol

 

[telectrix]

it also depends on what will fit. the 2.1ah are loner and slimmer than the 2.8ah. whareabouts are you in the UK?

 

[tazz]

Is just a alarm in a mate's house never heard of brand and cant remember .it began with s .lol

Then just change the battery and hope for the best....!!!

 

[ipf]

I just wish everybody would change their batteries regularly. Woken up last night after a power cut.....bloody sounders blasting all over the place.
Same again an hour ago, sort the timers and clocks out before I hit the sack...in hope :censored:

 

[tazz]

And will only last the power cut if the correct, calculated size is fitted

 

[ipf]

Basic house alarms, they should be able to sort that out.

 

[chopper]

It was a sterling 10 panel. Put battery 2.1 in seemed to work fine.not used these panels before only fitted veritas 8 and r8 etc. There was no info in it. Had to fit battery vertically

 

[tazz]

So how long will your battery last in a power cut...?????
Looking at sterling 10 manual battery requirements 2.8a/h - 7.2a/h
current Main panel 130mA, lcd keypad 100mA, zone loop current per zone min 0.76mA add siren, and pirs

 

[telectrix]

top of me head, without using too much brain power, he should get about 4 hours.

 

[tazz]

top of me head, without using too much brain power, he should get about 4 hours.

Not bad Tele..abaut 4.2hours, without SLA factor of 1.25......so not very long...7a/h would be more towards the mark and fitted better in panel.
I know some of you think this is over the top...but without calculating the size required, the system will just trigger the siren unit when the battery discharges in a power cut...hence leading to everyone getting really cheesed off at 2am