Magnum Energy ME-G Series - Manual (Page 54)

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2015 Sensata Technologies
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 for each load (see Table B-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
e) Divide by seven = Average Daily Watt-Hours Per Load.
Average Daily Watt-Hours Per Load
AC load Watt-Hours (x) hours per day (x) days per week ( ÷ 7) = total power
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.
2. Determine the total power needed each day for all the loads.
• Add Average Daily Watt-Hours Per Load = Total Daily Watt-Hrs.
Total Daily Watt-Hours
Total Amp-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 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.
x ___ =
(days of storage)
÷ ___ =
(inverter battery voltage)
Temperature 80F/27C 70F/21C 60F/15C 50F/10C 40F/4C 30F/-1C 20F/-7C
Multiplier 1.00 1.04 1.11 1.19 1.30 1.40 1.59
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.
Inverter effi ciency: When the inverter is used in a back-up power application the inverter effi ciency
is not 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.