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

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.

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

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Edited July 24, 200817 yr by 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

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?

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

and irrelevant for battery calcs

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

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

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