Doosan D35S-5 Service Manual page 135

Output Current Test
This test is to check whether the alternator output
current coincides with the rated current.
1. Preparation works
When the output current is measured, use the
battery discharged a little bit. It is difficult to
perform the accurate test with the fully charged
battery because of insufficient load.
a. Turn tile Ignition switch "OFF".
b. Disconnect the battery ground cable.
c. Disconnect the alternator output wire from "B"
terminal of the alternator.
d. Connect a DC ammeter (0~150A) to "B" terminal
and the disconnected output wire.
Connect (+) lead wire and (-) lead wire to "B"
terminal and output Wire, respectively.
Since it has high voltage, make sure to tighten
the connection completely using bolts and nuts
not clips.
e. Connect the voltmeter (0~20V) between "B"
terminal and ground terminal Connect (+) lead
wire to "B" terminal and (-) lead wire to ground
terminal at the proper position.
f. Connect engine tachometer And then connect
battery ground cable.
D439E Service Manual
CAUTION
CAUTION
2. Test
1) Check to see If the voltmeter Indicates the
same voltage value with battery voltage.
If voltmeter Indicates OV It means wiring
between "B" terminal of alternator and (-)
terminal of battery may be disconnected.
Otherwise, It means fusible link is short or
ground is poor.
2) Start the engine and turn the headlight switch
"ON".
3) Set the headlight on "High" and place the
heater blower switch at " HIGH" Measure the
max output current by accelerating the engine
speed up to 2500rpm.
NOTE : Since charging current drops down rapidly
after engine is started, perform this test quickly to
get accurate max current.
3. Result
1) Measured value from the ammeter should be
greater than the limit value. Despite that the
alternator output wire is normal. If the
measured-value is low, remove the alternator
and check it.
Output current : 70% of the rated current
• Rated output current is shown on the
identification plate attached on the alternator
body.
• Since output current varies depending on the
electric load of the alternator and ambient
temperature, it is difficult to get the rated
output current if the electric load of the vehicle
is low. In that case, turn the headlight on to
result in the battery discharging or increase
the electric load by using additional light from
other vehicle.
• Since rated output current cannot be measured
when the temperature of alternator and ambient
temperatures are too high, you should lower
the temperature before the secondary test.
2) After completing the output current test, lower
the engine speed down to the idle rpm and turn
the Ignition switch "OFF".
133 3. Engine Electrical System (D439E)
CAUTION