Battery Sizing Example
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Battery Sizing Example
This example illustrates a typical calculation, assuming an
opportunity to charge the batteries every three days.
This example illustrates how quickly your battery needs can
escalate. To reduce the required battery size, you can
conserve energy by eliminating or reducing the use of some
loads or re-charge more frequently.
When sizing your battery, resist the temptation to skip the last
step of this calculation (multiplying by 2). More capacity is
better since you will have more reserve capacity, be better
able to handle large loads and surge loads, and your battery
won't be discharged as deeply. Battery life is directly
dependent on how deeply the battery is discharged. The
deeper the discharge, the shorter the battery life.
Appliance
(A) Power
Consumption
(B) Operating
Time per Day
Daily watt-hours
needed for this
appliance
(= A x B)
TV & VCR 115 W 3 hours 345 Wh
Sewing machine 150 W 1 hour 150 Wh
Bread maker 600 W 1 1/2 hour 900 Wh
Blender 300 W 15 min = 1/4 hour 75 Wh
Total Daily watt-hours of AC load 1470 Wh
x Number of Days between charges 3
= Total watt-hours of AC load between charges 4410 Wh
Battery Ah used between charges (divide by 10) 441 Ah
Recommended Battery Bank Size in Ah (multiply by 2) 882 Ah
