Estimating Battery Requirements; Battery Sizing Example - Xantrex PROwatt 3000 Owner's Manual

Battery Types and Sizes

Estimating Battery Requirements

Battery Sizing Example

C–4
To determine how much battery capacity you need:
1. Determine how many watts are consumed by each appliance that you
will operate from the PROwatt 3000. You can normally find this on a
label 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.
This battery sizing example illustrates a typical calculation, assuming an
opportunity to charge the batteries every three days.
Appliance
TV & VCR
Microwave oven
3 lamps, 60 W each
Coffee maker
Coffee grinder
Hair dryer
Sewing machine
Washing machine
Steam iron
= Total watt-hours of AC load between charges
Battery Ah used between charges (divide by 10)
Recommended Battery Bank Size in Ah (multiply by 2)
(A) Power (B) Operating
Consumption Time per Day
115 W
1500 W 15 min = 1/4 hour
180 W
750 W 15 min = 1/4 hour
100 W 1 min = 1/60 hour
1500 W 6 min = 1/10 hour
150 W 30 min = 1/2 hour
1500 W 30 min = 1/2 hour
700 W 6 min = 1/10 hour
Total daily watt-hours of AC load
x Number of days between charges
Daily watt-hours
needed for this
appliance
(= A x B)
3 hours 345 Wh
375 Wh
4 hours 720 Wh
187.50 Wh
16.70 Wh
150 Wh
75 Wh
750 Wh
70 Wh
2689.20 Wh
3
8067.60 Wh
806.70 Ah
1613.40 Ah