PREVOST LE MIRAGE XLII BUS SHELLS, Maintenance Manual

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EFGGHI EFGGHI
Incorporated
Testing and Trouble Shooting
BATTERY EQUALIZER OWNER’S MANUAL 14
5. Subtract Battery A voltage from Battery B voltage and compare readings.
Voltage Comparison
Indicator
Light
Equalizer Status
a.
Battery A is lower than Battery B but
within 0.05 volt.
OFF OFF
Stand-by Mode.
The equalizer will not turn ON until Battery A is
lower than Battery B by more than 0.05 volts.
b.
Battery A is lower than Battery B by
0.05 to 0.10 volts.
ON ON Normal Operating Mode
c.
Battery A is lower than Battery B by
more than 0.10 volts
ON ON
Self-Protection Mode due to Overload
Condition. See below.
d.
Battery A is lower than Battery B by
more than 0.10 volts
OFF OFF
The Equalizer is not functioning
properly.
e. Battery A is higher than Battery B
Abnormal condition. Suspect Battery B is defective or a 12 volt load
is connected to Battery B.
Overload Condition on Family 3, Family 4 and Family 5 Equalizers
An overload condition exists when the 12 volt loads exceed the equalizer’s rated capacity. The overload
condition will not damage the equalizer but may cause damage to the batteries.
During the overload, the equalizer output is limited by internal protection circuits to its Rated Output
Amps. The 12 volt amps exceeding the equalizer output are drawn from Battery A which will begin to
draw the batteries out of balance. The equalizer full Rated Output Amps are maintained as long as
Battery A and Battery B remain balanced within 0.10 volt. The internal protection circuits will reduce
equalizer output as the batteries become further out-of-balance. If Battery A voltage falls below
approximately 8 volts the equalizer will shut itself OFF.
To correct the overload condition the 12 volt load must be reduced or the equalizer capacity must be
increased.
Trouble Shooting an Engine No-Start Situation
Situation:
A coach has dead batteries and won’t start while jump starting. The coach is equipped with a 24 volt
starting and charging system, a 12 volt electronic diesel engine control, a Family 3, 4 or 5 Equalizer, and
a moderate 12 volt load which cannot be turned OFF. The coach sits for several days and the batteries
run completely dead. During jump starting the engine cranks but does not start due to low voltage on the
12 volt supply. Electrical testing reveals there is no 12 volt output from the equalizer while jump starting
even though the equalizer separately tests OK.
Cause:
The 12 volt load which could not be turned OFF first ran both batteries down until the equalizer shut itself
OFF due to low voltage. (Family 3, 4 and 5 Equalizers will shut OFF if system voltage falls below 16 volts
or if voltage on either battery falls below 8 volts.) Then Battery A alone was drained to near zero volts.
As the bus is being jumped, 12 volt loads hold Battery A voltage too low for the equalizer to turn ON and
Battery A is too weak to support the 12 volt electronic engine control.
Solution:
Turn OFF all 12 volt loads (turning the battery disconnect switch OFF may accomplish this). Connect the
jumper cables but do not crank the engine for two or three minutes or until the equalizer indicator light has
turned ON which means the equalizer is ON. (Both batteries must rise above 8 volts.) The battery
disconnect switch can then be turned ON and the bus should have adequate 12 volt power to start.