Xantrex Technology Freedom SW 2000 user service Battery Information

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

			Daily watt-hours needed for
	(A) Power Consumption	(B) Operating Time per Day	this appliance
Appliance	(Watts)	(Hours)	(= 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

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.

38 Freedom SW 2000 Installation Guide