Airpax Dimensions MIL-24X26UVQ Owner's Manual - page 23
23
Chart E:
Battery Configuration:
Batteries interconnect in two ways: Series or parallel.
a) Series configuration: Increases voltage while keeping the Ampere Hour (AH) capacity
constant. For example: Two deep cycle 12 Volt batteries @ 105 AH each connected
in series, results in a total output of 24 Volts (12 Volts + 12 Volts) @ 105 AH
b) Parallel configuration: Increases capacity while keeping the voltage constant. For
example: Two deep cycle batteries 12 Volt @ 105 AH each connected in parallel,
results in a total output of 12 Volt @ 210 AH (105 AH + 105 AH).
Note: The amount of electrical energy in these two configurations is identical.
Chart F:
Useful Formulas
Ohm’s Law
Voltage (Volts) = Current (Amps) x Resistance (Ohms)
Power (Watts) = Voltage (Volts) x Current (Amps)
Chart G:
Sizing the Battery Bank
The first step is to estimate the total watts of load and how long the load is to
operate. Look at the input electrical nameplate for each appliance (see chart D, page
22) and adding up the total requirement can determine the total load wattage. Some
loads are not constant, so estimations must be made. An example is a full-size
refrigerator (750 watt compressor) running 1/3 of the time would be 250 watts per
hour. Also, the amount of time these loads are to operate from the inverter must be
decided.
After the load and running time are decided, the battery bank size can be
calculated. For a 24-volt inverter system, each 100 watts of load on the inverter
requires 5 amps DC from the battery, a 20 to 1 ratio.
An example of this calculation is:
1. Total = 1000 watts per hour
2. Watts from 24 volt battery = 1000 / 20 = 50 AH
Next the number of ampere hours (AH) must be multiplied by the time in hours that
the load is to operate. For example, the load is to operate 3 hours:
For a 24 volt system: 50 amps DC x 3 hours = 150 amp hour (AH).
During periods of heavy DC current draw, less than 100% of stored battery energy is
usable. A safe assumption is 50% usable energy. Therefore, to provide 150 AH of usable
energy a 300 AH capacity battery bank is required.
a) Series Configuration:
Each battery is 12V – 105 AH
b) Parallel Configuration:
Each battery is 12V – 105 AH
+
12VDC, 210 AH
-
+
24VDC, 105 AH
-