Hi, could some on tell me who to work out the size of a battery needed to back up the system for 12 and then 24hrs.

 

We've just taken over a national trust site and they require 24hrs back up though out the whole system. 

 

Thanks

Hi, could some on tell me how to work out the size (Ah) of a 12v battery needed to back up the system for 12hrs and then 24hrs.

 

We've just taken over a national trust site and they require 24hrs back up thoughout the whole system. 

 

Thanks

Have you tried a site Search ?, Sure there's a calculator on here somewhere.

Take a look at the nsi site, there's a quick & simplified calculator on there.

17 hours ago, james.wilson said:

 

 

That's perfect 

 

Thank you

 

 

I always thought it was x 1.2 but the BSIA example shows 1.25. 

 

Every day is a school day as they say  

I recall it as 15 minute activation not 30 minutes. Seen as the bell timer would be 15 minutes the alarm current after 15 minutes will be different on an SAB.

Was sure the standard says something along the lines of "12 (24) hours standby including one full activation"?

Still useful chart tho, not a bad thing to be overspec standby capacity wise.

On 20/05/2019 at 22:34, sixwheeledbeast said:

I recall it as 15 minute activation not 30 minutes. Seen as the bell timer would be 15 minutes the alarm current after 15 minutes will be different on an SAB.

Was sure the standard says something along the lines of "12 (24) hours standby including one full activation"?

Still useful chart tho, not a bad thing to be overspec standby capacity wise.

30 mins for fire alarms. 

 

15 mins intruder. 

Eh? Who mentioned fire?