“Charging System of an Automobile Study 3”

= Output Current Test=
(Click here to Study 2)
* This test determines whether or not the alternator gives an output current that is equivalent to the normal output.
PREPARATION:

1. Prior to the test, check the following items and correct as necessary. Check the battery installed in the vehicle to ensure that is good condition. the battery checking method is described in the section “Battery”. The battery that is used to test the output current should be that has been partially discharged. With a fully charge battery, the test may not be conducted correctly due to an insufficient load. Check the tension of the alternator drive belt”.
2. Turn off the ignition switch.
3. Disconnect the battery ground cable.
4. Disconnect the alternator output wire from the alternator “B” terminal.
5. Connect a DC Ammeter () to 15A) in series between the “B” terminal and disconnected output wire. Be sure to connect the (-) lead wire of the Ammeter to the disconnected output wire.
   
   NOTE:
   = Tightened its connection surely, as a heavy current will flow.
   
6. Connect a volt meter(0 to 20V) between the “B” terminal and ground. Connect the (+) lead wore to the alternator “B” terminal and (-) lead wire to a good ground.
7. Attach an engine tachometer and connect the battery ground cable.
8. Lead the engine hood cable.

TEST:

1. Check to see that the voltmeter reads as the same value as the battery voltage. If the voltmeter read 0V, and the open circuit in the wire between alternator “B” terminal and battery (-) terminal or poor grounding is suspected.
2. Start the engine and turn on the headlamps.
3. Set the headlamps to high beam and the heater blower to high, quickly increase the engine speed to 2,500 rpm and read the maximum output current value indicated by the ammeter.
   
   NOTE:
   After the engine start up, the charging current quickly drops.
   Therefore, the above operation must be done quickly to read the maximum current value correctly.

RESULT:

1. The ammeter reading must be higher than the limit value. If it is lower but the alternator output wire is in good condition, remove the alternator from the vehicle and test it.
   Limit value: 91A min.(130A alternator.
   
   NOTE:
   1) The nominal output current value is shown on the nameplate affixed to the alternator body.
   2) The output current value changes with the electrical load and the temperature of the alternator itself.
   Therefore, the nominal output current may not be obtained. if such is the case, keeps the headlamps on the cause discharge of the battery, or use the lights of the another vehicle to increase the electrical load.
   The nominal current may not be obtained if the temperature of the alternator irself or ambient temperature is too high.
   In such a case, reduce the temperature before testing again.
2. Upon completion of the output current test, lower the engine speed to idle and turn off the ignition switch.
3. Disconnect the ground cable.
4. Remove the voltmeter and the ammeter  and tachometer.
5. Connect the alternator output wire to the alternator “B” terminal.
6. Connect the battery ground cable.