A-6 Electrical ASE Test Preparation     

Charging System

1. The alternator brush rides on a:

slip ring.


2. The voltage regulator directly controls:

field current.
output current.
stator circuit.


3. If a conductor is moved through a magnetic field:

heat is created.
voltage is created.
the magnetic field is increased.
the magnetic field is decreased.


4. The magnetic field in an alternator is developed in the:

none of the above.


5. The rotor's field current is controlled to regulate

alternator output current.
diode voltage.
stator resistance.
none of the above.


6. When most of the electrical accessories are turned on, the electrical system will demand (need):

lower alternator output.
higher alternator output.
both A and B.
neither A nor B.


7. In an alternator, alternating current is converted to direct current by the:



8. The purpose of the alternator stator is to:

change alternating current to direct current.
have voltage induced in its windings.
build up a strong magnetic field.
conduct the field current.


9. When the input voltage to a regulator decreases, the alternator output voltage should normally:

remain the same.
turn ON the charging lamp indicator.


10. A battery that is overcharged can be due to:

loose alternator drive belt.
defective regulator.
high speed driving.
high resistance in the field circuit.


11. If the charging system is below the rated output, the technician should next test the:

ground-circuit resistance.
insulated-circuit resistance.
alternator output (full-field test).
none of the above.


12. A charging system output test for an 70 amp alternator indicates a 64 amp output. Technician A says that an alternator output (full field) test should be performed to determine what component should be replaced. Technician B say the output is sufficient and nothing needs to be done. Who is correct?

technician A.
technician B.
both A and B.
neither A nor B.


13. A vehicle failed a charging system output test. Technician A says if you supply full-fielded current to the alternator, and the charging voltage and current increases to normal levels, you usually have a bad regulator. Technician B says some alternators can be full-fielded by grounding the alternator output battery terminal. Who is correct?

Technician A only.
Technician B only.
both Technician A and Technician B.
neither Technician A and Technician B.


14. While testing an alternator with an oscilloscope and the waveform appears as shown below. What would this indicate:

normal condition.
a problem with the requlator's switching transistor.
a problem with the diodes.
a problem with the stator.


15. When performing an charging system output test using a VAT-40 load tester, the engine RPM should be:

Idle RPM.
2000 RPM
4000 RPM
Wide open throttle.


16. When performing an charging system output test using a VAT-40 load tester, to test current output the battery should be loaded:

to no less than 13.0 volts.
to no less than 12.0 volts.
to no less than 11.0 volts.
to no less than 9.6.0 volts.


17. In the test being performed in the illustration below. What is the maximum specification allowed?

0.1 volts.
0.2 volts.
0.5 volts.
1.0 volts.


18. A rectifiery Bridge is being tested with a DVOM is set to 'DIODE CHECK'. One lead is connected to a diode lead and the other lead is connected to the diode housing. The connections are then reversed and both readings noted. One reading is 'OL' and the other is 0.5v. Technician A says that the diode is shorted. Technician B says that this is a normal indication. Who is correct?

technician A.
technician B.
both A and B.
neither A nor B.


19. During an alternator output test, you find that the output is zero amps and the voltage is 12 volts. Your next step should be to:

replace the regulator.
full-field (Alternator output test) the alternator and check the readings.
remove the alternator for bench testing.
test the battery.


20. High resistance in an alternator output circuit is often caused by?

a discharged battery.
a shorted diode.
loose or corroded connections.
a bad regulator.


21. An A-type (Grounded-Regulator) charging system is full-fielded by connecting a jumper wire from the:

'F' terminal of the regulator to battery positive terminal.
alternator 'F' terminal to ground.
battery positive terminal to ground.
battery positive terminal to the alternator battery terminal.


22. Technician A says a higher than normal charging system voltage is usually caused by a defective alternator rectifier diode. Technician B says a defective battery can affect the charging system.

technician A only
technician B only
both technicians A and B
neither technicians A nor B


23. A charging system is being discussed: An engine in run at 2000 RPM, the headlights highbeams are ON and the Blower Fan is set to high speed. Current is being measured at the alternator output wire and voltage is measured at the battery.

Specifications: Alternator 70 amps max, Regulator voltage 14.1 to 14.9.

Technician A says alternator output current should be above 30 amps and the voltmeter should read between 14.1 and 14.9. Technician B says this is too low and the alternator should be 70 amps and no lower than 14.1. Who is correct?

technician A only
technician B only
both technicians A and B
neither technicians A nor B


24. A charging system has failed a system test (5 amps @ 12.7 volts). An alternator output full field test is performed. The technician finds that the alternator output is now within 10% of its rated output. Therefore:

the regulator is defective
the alternator is defective
a wiring problem exists
both regulator and the alternator are defective



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