Calculating Battery Required For Grade 3 Alarm

[pjwallis]

Hi

Does any one know how to calculate the size of battery required for an intruder alarm system, which is in this case Grade 3 and there ore requires 24Hr back up as there is no mains failure transmitted to ARC.

Many thanks

Paul

[james.wilson]

http://www.thesecurityinstaller.co.uk/comm...showtopic=23764

We use this application to do the calc, but if your not signalling ac fail (may i ask why) you will need 24 hours standby time.

[Guest anguscanplay]

http://www.thesecurityinstaller.co.uk/comm...showtopic=23764

We use this application to do the calc, but if your not signalling ac fail (may i ask why) you will need 24 hours standby time.

shouldn`t the battery disconnect too .............. 10V IIRC

.

[james.wilson]

most panels now include some sort of battery saving but to be fair if a lead acid drops to 10v its usually scrap afterwards

[Guest anguscanplay]

most panels now include some sort of battery saving but to be fair if a lead acid drops to 10v its usually scrap afterwards

nah I thought it was in the regs?

[james.wilson]

in the control panel reg not the installer reg, and irrelevant for battery calcs

[Guest anguscanplay]

and irrelevant for battery calcs

but if the O/P calculated the battery down to 6V? - relevant then

[james.wilson]

so you dont use the rated power marked on batteries then?

[Guest anguscanplay]

so you dont use the rated power marked on batteries then?

yesh but so do so many other industries that dont have such draconian regs

do the maths - your counting the battery down to fully discharged so a 7AMP battery could supply 930ma for seven hours / 575ma for 12hours etc but the regs say it has to disconnect at 10V (IIRC) so your formula is flawed

Roughly speaking if the cut off is 2/3 of the starting voltage then your 7AMP should only be used for 1/3 of the rated power - max 190ma supply?

I dont know, I`m just repeating what others have told me - thats why its easier to signal mains loss IMO