Xantrex Technology PROwatt 600 User Manual

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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