Xantrex7 UX - REV A Owner's Manual page 83

Appendix B - Batteries
Estimating Battery Requirements (continued)
Step 1 Determine the loads the inverter will power and list them in the Step 1 column.
Step 2 Enter the running wattage of each appliance in the Step 2 column.
Step 3 Determine the number of hours (or fraction of hours) the appliance is used each day. Enter this figure in the Step 3 column.
Step 4 Determine the number of days the appliance will be used during the week. Enter this figure in the Step 4 column.
Step 5 Divide the number (entered into each row of the Step 4 column) by 7 to obtain the AVERAGE DAILY WATT HOURS REQUIRED figure.
Enter these figures in the Step 5 column.
Step 6 Add all the figures entered into the AVERAGE DAILY WATT HOURS REQUIRED (Step 5) column and enter this number into the TOTAL
DAILY WATT HOURS REQUIRED (Step 6) column in the second table.
Step 7 Multiply the TOTAL DAILY WATT HOURS REQUIRED (Step 6) figure by the number of days of autonomy (days between recharging
expected, usually between 1 to 5. The examples use 3). Enter this figure into the AUTONOMY BATTERY SIZE (Step 7) column.
Step 8 Multiply the AUTONOMY BATTERY SIZE (Step 7) figure by 2 to provide a 50% maximum battery discharge level. Enter this figure in the
ROUGH BATTERY SIZE (WATT HOURS) (Step 8) column.
Step 9 Multiply the ROUGH BATTERY SIZE (WATT HOURS) figure (Step 8) by 1.2 and enter this figure in the SAFE BATTERY SIZE (WATT HOURS)
(Step 9) column. This figure allows for an efficiency of 80%.
Step 10 Divide the SAFE BATTERY SIZE (WATT HOURS) (Step 9) figure by the DC system voltage (i.e., 12, 24 or 48 volts). Enter this number in the
SAFE BATTERY SIZE (AMP HOURS) (Step 10) column. Use this figure to determine the number of batteries required to reach the amp-
hour rating.
©2002 Xantrex Technology Inc. All Rights Reserved.
P/N 975-0026-01-01 Rev A 06/2002
B-5