User’s Manual—Please read before using this equipment.
11
(fully charged) then drops to 10.6 volts (discharged). If the load on the battery causes
the battery to discharge faster than the 20 hour rate, the capacity (Ah) of the battery is
measurably reduced (derated). Derating is a major run time factor. The curve below can help
to determine what the battery bank can deliver under load. The results are used to estimate
how much additional battery capacity is needed to achieve the desired run time.
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% (horizontal number) of the Ah
(20 hour rate). Starting at the 100% horizontal point and looking up to the curve the results
are that only 56% 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% of the 20 hour rate yields only 31% 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 a 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.
© 2008 Wagan Corporation.
All Rights Reserved.
Wagan and wagan.com are trademarks used by Wagan Corporation.
Summary of Contents for 2007-2
Page 1: ...Item no 20072 User s Manual 3000 Watt AC Inverter R ...
Page 19: ......