Owners Manual

© 2013 Magnum Energy, Inc.Page 49
Appe ndix B – Bat t e ry I nform at ion
B- 5 Bat t er y Ba nk Sizing W or k shee t
Complete the steps below to determine the battery bank size required to power your AC loads:
1 . D eterm ine t he daily pow e r nee de d 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 = Aver age Da ily W a t t - Hou rs Per Loa d.
Average Daily Watt-Hours Per Load
AC load Watt-Hours (x) hours per day (x) days per week
(
÷
7) = daily Wh/load
4 . D eterm ine how de eply you w a nt to discharge you r batterie s.
• Divide the St orage Am p-Hours by 0.2 or 0.5 to get the Total Am p- H our s:
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 . D eterm ine t he t ot al pow er needed e a ch day for all t he loa ds.
• Add the Average Daily Watt- Hours Per Load together = Tot a l Daily W a tt-
Hou rs.
Tot al Da ily W a tt - Hour s
Tot al Am p- H our s
3 . D eterm ine t he batter y Am p- H ou r ca pacit y n eeded t o run
all t he loa ds before rech arging.
• Divide the Tot al Daily Wat t -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) = St or age Am p- Hou rs.
x _ _ _ =
(days of storage)
÷ _ _ _ =
(inverter battery voltage)
Temperature 27C/80F 21C/70F 15C/60F 10C/50F 4C/40F -1C/30F -7C/20F
Multiplier 1.00 1.04 1.11 1.19 1.30 1.40 1.59
Addit ional com pe nsation:
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 Tot al Am p-Hours by the Mult iplier below.
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 Am p-
Hours should be multiplied by 1.2 to factor in an average 80% inverter effi ciency.