Answer Posted / nbs

that is depending on your back reqirment.you should metion
ups rating and how much time you need back, input voltage (
1 phase or 3 phase).
Hwre iam giving one example:
if you have Ups =5KVA
bacck ups requirent is = 2hr


batteries/battery capacity reqirement:

dischage current = 5000X 0.8
-----
0.9 X 12
=370.37 A

battery capacity = 370.37 X2 = 740.AH

you can take = 4 No.s x180 AH
total no.of batteries = four 180AH batteris

Note:
at dischage current , 0.9 inveter efficency
12v battery voltage

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