Battery Types

Estimating Battery Requirements

To determine how much battery capacity you need:

1.Determine how many watts are consumed by each appliance that you will operate from the XM 1800. You can normally find the watt rating labelled on the product. If only the current draw is given, multiply it by 115 to get the power consumption in watts.

2.Estimate how many hours each appliance will be operating each day.

3.Calculate the daily watt-hours needed for each appliance.

4.Add the total number of watt-hours needed for all the appliances and multiply it by the number of days between charges.

5.Divide the total watt-hours of AC load between charges by 10. This gives the battery Ah used between charges.

6.Double the total Ah used between charges to get the recommended battery size in Ah.

See the battery sizing example that follows.

Battery Sizing Example

This battery sizing example illustrates a typical calculation, assuming an opportunity to charge the batteries every three days.

 

 

 

Daily watt-hours needed

 

(A) Power

(B) Operating Time

for this appliance

Appliance

Consumption (Watts)

per Day (Hours)

(= A × B)

 

 

 

 

 

 

 

 

TV & VCR

200 W

2 hours

400 Wh

 

 

 

 

Microwave oven

1000 W

20 min. = 1/3 hour

333 Wh

 

 

 

 

3 lamps, 60 W

180 W

4 hours

720 Wh

each

 

 

 

 

 

 

 

Coffee maker

600 W

15 min. = 1/4 hour

150 Wh

 

 

 

 

Steam iron

700 W

6 min. = 1/10 hour

70 Wh

 

 

 

 

 

 

 

 

Total daily watt-hours of AC load

1673 Wh

 

 

 

 

× Number of days between charges

3

 

 

 

 

 

 

 

= Total watt-hours of AC load between charges

5019 Wh

 

 

 

 

Battery Ah used between charges (divide by 10)

502 Ah

 

 

 

 

Recommended Battery Bank Size in Ah (multiply by 2)

1004 Ah

 

 

 

 

B–4

975-0263-01-01

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Xantrex Technology XM 1000, XM 1800 manual Estimating Battery Requirements, Battery Sizing Example