Wagan ProLine 2007-2 User Manual page 9

User's Manual—Read before using this equipment
The left vertical numbers of the curve represents percentage of the battery capacity at the
20 hour rate. In this example, the user needs a one hour run time. If the example battery is
220AH (20 hour rate), and the load is 220 amps that is 100 percent (horizontal number)
of the AH (20 hour rate). Starting at the 100 percent horizontal point and looking up to
the curve the results are that only 56 the percent of the battery capacity is available. This
means that a higher battery capacity is required to get the desired run time, one hour. The
curve also shows that a load of 200 percent of the 20 hour rate yields only 31 percent of
the battery capacity. The installer must carefully plan the capacity of battery bank or the run
time may be seriously affected. To the inexperienced installer, several trial battery capacities
may be required to make sure the large enough battery capacity is available to achieve the
desired run time.
The curve can be applied to any lead acid battery under load providing that it has an AH
rating at the 20 hour rate.
Continuing with the previous example: The 150 amp load will need to run for 10 hours, so
we begin configuration with a 1,500 AH battery. If the vertical is 1,500 and the horizontal
is 150 amps, the percentage of load on the battery is 10 percent. The curve shows that the
1,500 AH is derated to 90 % of maximum. This means that the battery will have to be 1,650
AH for the full 10 hour run time. It is important to add some extra battery capacity, because
as the batteries age, they will lose AH capacity.
CONFIGURATING THE BATTERY BANK
Twelve volt, 220 AH batteries were selected for these illustrations because they are generally
readily available and relatively inexpensive. They are deep-cycle type and with regular
recharging they have a relatively long life. These batteries are "flooded" type; they freely
vent hydrogen and oxygen while under charging and heavy discharge. They must be vented
to outside air to prevent accumulation of explosive gases.
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