Installation Manual

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 Tot a l Am p-

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 con-

sidered a realistic trade-off between battery cost and battery life.

Tot al Am p- H our s

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

output current 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 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.

C.2 Ba t t e ry Bank Sizing W orksheet

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 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 = Avera ge D aily W at t - H ours Per Loa d.

Average Daily Watt-Hours Per Load

AC load watt-hours (x) hours per day (x) days per week

(

7) = total power

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 Wat t- Hours Per Load together = Tot al D aily W at t -

Hours.

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 recharging.

• Divide the Total Daily Watt-Hours by the nominal battery volt-

age of the inverter (i.e. 12, 24 or 48 volts); and

• Multiply this by how many days the loads will need to

run without having power to recharge the batteries (typi-

cally 3 to 5 days of storage) = St or age Am p- H ours.

x _ _ _ =

Tot al Da ily W a tt - Hour s

(days of storage)

÷ _ _ _ =

(inverter battery voltage)

Appe ndix C - Bat t e ry I nfor m at ion