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Planning for AC Loads
975-0337-01-01 2–7
Running the Alternator While Operating AC and DC Loads
Recharging Running the alternator does not guarantee that the battery is being fully
recharged by the alternator if you are running a combination of large AC
and DC loads.
The alternator must provide more power than the draw of the combined
DC and AC loads for your battery to fully recharge.
Example This example for a 12 volt battery shows what happens if the alternator is
overloaded.
The alternator is charging at 130 amps while the engine is running and
there is a 1000 W (AC) load.
The efficiency of the inverter/charger is approximately 90%, which
means it is drawing about 1100 W (DC) from the battery or 92 amps. This
leaves 38 amps for all DC loads. If the DC loads require more than 38
amps, the battery will actually discharge even though the alternator is
running.
Figure 2-2
AC and DC loads powered by the alternator
12 Volt Battery
Alternator
(130 A)
IP1012 AL
DC Loads
AC Loads
(1000 W)
Owner Installed
Loads
Factory
Installed
92 A
1100 W (DC)
38 A
IP1012_AL.book Page 7 Tuesday, May 1, 2007 12:18 PM