Session 6: Circuit Diagram of Charging System of Automobile and Checking of Charging System
Module 5: Auto Electrical System
Textual Question-Answers
Check Your Progress
Fill in the blanks
1. Routine maintenance of the alternator involves checking the……………. and ensuring the tightness of connecting bolts.
Ans: driving belt
2. During the alternator testing on the vehicle, if the ignition warninglamp remains illuminated while the engine is running, it could be dueto a………………
Ans: defective alternator
3. Diodes can be tested individually using a 12-V battery and awarning lamp with test prods of ……………. V and W, respectively.
Ans: terminals
4. If the ignition warning lamp fails to illuminate when the ignitionis switched on, a possible cause could be a ………………or………….
connection.
Ans: blown bulb or open
Multiple Choice Questions (MCQs)
1. What is the purpose of using alternators in modern vehicles insteadof dynamos?
a) To increase generator speed
b) To decrease generator size
c) To overcome brush and commutation limitations
d) To reduce electrical load
Ans: c) To overcome brush and commutation limitations
2. What precautions should be taken before checking the charging system?
a) Disconnect the battery
b) Flash the alternator output leads
c) Use a slave battery to start the engine
d) Ensure all connections are secure and clean
Ans: d) Ensure all connections are secure and clean
3. What should be the belt deflection when checking the drivingbelt’s condition?
a) 5-10mm
b) 10-15mm
c) 15-20mm
d) 20-25mm
Ans: b) 10-15mm
4. In the alternator checking procedure, if the warning lamp doesnot go off when the engine starts, what could be the issue?
a) Loose belt
b) Faulty ignition switch
c) Defective alternator
d) Disconnected battery
Ans: c) Defective alternator
5. What is the purpose of inserting an ammeter and a voltmeterduring alternator testing?
a) To measure engine speed
b) To measure battery voltage
c) To measure field current and alternator voltage
d) To measure fuel consumption
Ans: c) To measure field current and alternator voltage
6. If the voltage during engine speed of 50 km/h falls below 13.5V orabove 14.4V, what might be the issue?
a) Faulty regulator
b) Loose battery terminal
c) Worn bearings
d) Shorted phase in the stator
Ans: a) Faulty regulator
Answer the following questions
1. Name the importance of circuit diagram of charging system ofautomobile and checking of charging system in a vehicle.
Ans: The circuit diagram of the charging system helps in understandingthe flow of current and connection of components such as alternator, battery,
regulator, and warning lamp. It assists technicians in locating faults easily.
Checking the charging system ensures proper battery charging, reliableelectrical supply, and prevents battery discharge or overcharging, therebyimproving vehicle performance and safety.
2. Draw the charging circuit of a modern car.
Ans: The charging circuit of a modern car includes the battery, alternator,
voltage regulator, ignition switch, warning lamp, fuse, and connecting wiresarranged to charge the battery while supplying electrical power to vehiclesystems.
3. Explain the procedure of testing the charging circuit step by step.
Ans: First, inspect the driving belt for condition and correct tension. Checkbattery terminals and wiring connections for tightness and cleanliness. Start
the engine and observe the ignition warning lamp. Measure battery voltagewith the engine running using a voltmeter. Insert an ammeter to check chargingcurrent. Compare readings with standard values to confirm proper operationof the charging circuit.
4. Explain the procedure of testing the following.
a. Alternator Stator
Ans: Disconnect the stator leads and use an ohmmeter to check continuitybetween stator windings. Ensure there is no continuity between winding andbody, indicating no short to ground.
b. Alternator Rotor
Ans: Check the rotor winding resistance using an ohmmeter across theslip rings. Also check for insulation between the rotor winding and shaft toensure there is no grounding.
c. Rectifier
Ans: Test rectifier diodes using a test lamp or multimeter. Current shouldflow in one direction only. If current flows in both directions or not at all, thediode is faulty.
5. Write different faults that may occur in the charging circuit,
their causes and remedies.
Ans: Common faults include low charging due to loose belt or faultyregulator, overcharging caused by defective regulator, no charging due to opencircuit or faulty alternator, and warning lamp remaining on due to diode orstator faults. Remedies include tightening or replacing belts, repairing wiring,
replacing faulty regulators, alternators, or rectifier units.
Activity
1. Prepare a poster showing the charging system of any vehicle.
Ans: The poster should show the battery, alternator, voltage regulator,ignition switch, warning lamp, and wiring connections clearly labeled toexplain the working of the charging system.
Try yourself.
2. Prepare a poster showing the testing of the alternator and regulatorof the vehicle.
Ans: The poster should illustrate alternator and regulator testing using avoltmeter and ammeter, showing connection points, test steps, and normal voltage and current values. Try yourself,
