Xantrex Technology 815-2524-02 manual Estimating Battery Requirements, Calculating Battery Size

Estimating Battery Requirements

Calculating Battery Size

Step 1: Compute Amp-hours

For each appliance, compute the number of amp-hours that will be used between charging cycles, as follows:

1.Obtain the wattage. If the wattage is marked on the nameplate rating, use that. Otherwise, multiply the marked voltage and amperage:

WATTS = VOLTS × AMPS.

2.Obtain the Watt-hours by multiplying that amount by the hours the appliance will be used:

WATT-HOURS = WATTS × HOURS.

3.Obtain the amp-hours that the appliance requires by dividing that amount by 20 (the factor for the Freedom SW 230V, which is a 24-volt system):

BATTERY AMP-HOURS USED = AC WATT-HOURS÷10

For example, a 100 W light bulb that is used for 4 hours will use 400 watt-hours (Wh) and the inverter will consume approximately

40 Ah from a 12-volt battery.

4.Enter this information on the blank calculation worksheet (page 56).

Battery Information

Step 2: Calculate Battery Size
5. Complete the rest of the worksheet; see Table 5, “Battery	only.
Sizing Example” on page 54 for an example.
Size the batteries at approximately twice the estimated total amp-	personnel
hour usage. Doubling the expected amp-hour usage ensures that the
batteries will not be overly discharged and extends battery life.
Do not skip this doubling step. More capacity is better since you	qualified
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	by
discharged. The deeper the discharge, the shorter the battery life.
	use
Troubleshooting If you find that the system shuts down when
	for
appliances with large motors are started, the problem may be that
this motor is too much for the battery. Even though you calculated	guide
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	This

a bigger battery) solves the problem.

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