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38 Freedom SW 2000 Installation Guide
Battery Information
Size the batteries at approximately twice the estimated total amp-hour
usage. Doubling the expected amp-hour usage ensures that the batteries will
not be overly discharged and extends battery life.
Resist the temptation to skip this doubling step. 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.
Troubleshooting If you find that the system shuts down when appliances
with large motors are started, the problem may be that this motor is too
much for the battery. Even though you calculated the amp-hour
requirements appropriately, the startup of a large motor makes high
demands on the battery. You may find that adding more amp-hours (in the
form of extra batteries or replacement with a bigger battery) solves the
problem.
Table 6
Battery Sizing Example
This example illustrates how quickly your battery needs can escalate. To
reduce the required battery bank size, you can either conserve energy by
eliminating or reducing the use of some loads, or recharge more frequently.
Appliance
(A) Power Consumption
(Watts)
(B) Operating Time per Day
(Hours)
Daily watt-hours needed for
this appliance
(= A × B)
TV & VCR 200 W 2 hours 400 Wh
Small microwave oven 800 W 15 min = 1/4 hour 200 Wh
3 lamps, 60 W each 180 W 4 hours 720 Wh
Coffee maker 600 W 15 min = 1/4 hour 150 Wh
Hair dryer 1500 W 6 min = 1/10 hour 150 Wh
Total daily watt-hours of AC load 1620 Wh
× Number of days between charges 3
= Total watt-hours of AC load between charges 4860 Wh
Battery Ah used between charges (divide by 10 for 12 volt system; divide by 20 for 24 volt system) 486 Ah
Recommended Battery Bank Size in Ah (multiply by 2) 972 Ah