Answer / manoj sharma

It is very simple. You should first know the voltage rating
of your load supplied by UPS. Let it is X volt. Now you
have to decide which type of batteries you want to use
according to nature of your load and maintenance factors.
There are mainly Lead-acid battery, NI-Cd battery and VRLA
battery. If you use Lead-acid battery. A lead acid battery
has 2.2V/Cell standard. So Number of battey cells are X/2.2
for Laed acid battery. Now second thing is what is ampere
requirement for your load and for how much time. Let you
want 30 A current for 10 hours. Then capacity of your
single cell of battery must be 30*10 means 300AH.

Answer / 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

Answer / shamim ahmed

You Should Know the KVA rating of your UPS, time you want
to get Back-up & the Battery input voltage of your UPS.If
your UPS rating is X , time T and the UPS input voltage is
V then the Battery current capacity is:

I=X*T*1.25/V*0.7 AHr

suppose battery input voltage of your UPS is 36V and you
find the Battery capacity from calculation is 300Ahr.

then you can use 3pcs 12V 300AHr battery in series or you
can use 2pcs 36V 150AHr battery in parallel.

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