Battery Sizing

saileshsharma2

Hello Is there any easy formula to calculate no of battery if there is given watthour, known system voltage.
like as Required Battery capacity= 7200 WHr And system Voltage is 48v
It comes 150 Ah .
Do u have any idea plz

mike95490

If your design comes up with 7200 wh being required  (Is that the daily load, or the final 20% discharge value)
7200 / 48v = 150 ah indeed.   Easy way is to use 8, 6V 200ah golf cart batteries in series.  Gives you a little extra
capacity, no parallel strings, and should be a solid 3-6 years lifetime.
Your charging source should be able to provide 20A @ 58V or about 1200W from a wall outlet, or about 1500w of well aimed PV panels.

mvas

saileshsharma2 said:

Hello Is there any easy formula to calculate no of battery if there is given watthour, known system voltage.
like as Required Battery capacity= 7200 WHr And system Voltage is 48v
It comes 150 Ah .
Do u have any idea plz

Yes, your formula is correct but ...
I would double the size of the batteries.
If you calculate 150 AH needed per day, then install 300 AH batteries  for 50% DOD max.
8 batteries x 300 AH x 6 volts each in series.
3 years at 50% Depth of Discharge = 1,000 deep cycles.

There are not very many batteries that can handle 50% DOD every day for 3 years.
Don't even think about using Marine (fake) "Deep-Cycle" batteries.