B-5 Battery Bank Sizing Worksheet - Magnum Energy MagnaSine MS-PE Series Owner's Manual

Appendix B – Battery Information

B-5 Battery Bank Sizing Worksheet

Complete the steps below to determine the battery bank size required to power your AC loads:
1. Determine the daily power needed for each load.
a) List all AC loads required to run; and
b) List the Watt-Hours (Wh) for each load (see Table C-1 for common loads/wattage); and
c) Multiply by how many hours per day (or a fraction of an hour) each load will be used; and
d) Multiply by how many days per week you will use the listed loads; and then
e) Divide by seven = Average Daily Watt-Hours Per Load.
AC load
2. Determine the total power needed each day for all the loads.
• Add the Average Daily Watt-Hours Per Load together = Total Daily Watt-
Hours.
3. Determine the battery Amp-Hour capacity needed to run
all the loads before recharging.
• Divide the Total Daily Watt-Hours by the nominal battery voltage of
the inverter (i.e., 12, 24 volts); and
• Multiply this by how many days the loads will need to run without
having power to recharge the batteries (typically 3 to 5 days of
storage) = Storage Amp-Hours.
4. Determine how deeply you want to discharge your batteries.
• Divide the Storage Amp-Hours by 0.2 or 0.5 to get the Total Amp-Hours:
a) 0.2 = Discharges the batteries by 20% (80% remaining), this is considered the
optimal level for long battery life; or
b) 0.5 = Discharges the batteries by 50% (50% remaining), this is considered
a realistic trade-off between battery cost and battery life.
Additional compensation:
Low battery temperature: If the batteries are installed in a location that will be exposed to low temperatures,
the available output will be less. In these instances, you will need to determine the lowest temperature the
battery bank will experience and multiply the Total Amp-Hours by the Multiplier below.
Temperature 27C/80F
Multiplier 1.00
Inverter effi ciency: When the inverter is used in a back-up power application the inverter effi ciency will not
be a large concern. However, if the inverter is the primary AC source for the calculated load, the Total Amp-
Hours should be multiplied by 1.2 to factor in an average 80% inverter effi ciency.
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Average Daily Watt-Hours Per Load
Watt-Hours (x) hours per day
21C/70F 15C/60F
1.04 1.11
(x) days per week
(inverter battery voltage)
÷ ___ =
(days of storage)
x ___ =
10C/50F 4C/40F
1.19 1.30
© 2013 Magnum Energy, Inc.
( 7) = daily Wh/load
÷
Total Daily Watt-Hours
Total Amp-Hours
-1C/30F -7C/20F
1.40 1.59