1. Before starting the test, check:
- generator installation;
- alternator drive belt tension;
- fusible insert;
- the absence of extraneous noise from the generator when the engine is running.
2. Turn the ignition key to position «OFF» («OFF»).
3. Disconnect a wire from the negative plug of the storage battery.
Pic. 9.1. Generator output voltage drop test circuit: 1 - generator; 2 - conclusion «IN»; 3 - voltmeter; 4 - ammeter; 5 - battery
4. Disconnect the wire from the terminal «IN» generator and connect an ammeter (direct current) with a range of 0-100 A in series between output «IN» and a wire disconnected from the generator (connect wire from «+» ammeter to output «IN» generator, and then the wire from «–» ammeter to the wire disconnected from the generator) (pic. 9.1).
Attention! It is recommended to use an ammeter with an inductive sensor («current clamp»), which allows you to measure the current without disconnecting the wire from the output «IN» generator. The use of this type of ammeter allows you to reduce the possible voltage drop due to poor contact of the wire with the output «IN» generator.
5. Connect a digital voltmeter to the terminal «IN» alternator and positive battery terminal (connect wire from «+» voltmeter to output «IN» generator, and the wire from «–» voltmeter - to the terminal «+» battery).
6. Connect a tachometer.
7. Reconnect the wire to the negative battery terminal.
8. Leave the car hood open.
9. Start the engine.
10. Maintaining engine speed 2500 min-1, turn on and off the headlights and outdoor lights, thereby adjusting the load on the generator so that the output current (shown on the ammeter) was slightly above 30 A.
11. Gradually reduce the engine speed until the current on the ammeter is 30 A. At the same time, read the voltmeter.
The maximum allowable voltage drop is 0.3 V maximum.
Attention! If the generator output is high and you are unable to bring the ammeter down to 30A by turning on the load, set the current to 40A. Read the voltmeter for this case.
12. If the voltmeter readings exceed the maximum permissible value, there is probably a malfunction in the circuit coming from the output «B» generator. In this case, you should check the circuits between the output «IN» alternator and positive battery terminal (including fusible link).
13. If the fastening of the wire to the generator output is loose or the insulation of the wires in the harness has changed color due to overheating, then eliminate the malfunction and recheck.
14. After checking, let the engine idle.
15. Turn off all exterior lights and ignition.
16. Disconnect a wire from the negative plug of the storage battery.
17. Disconnect the ammeter, voltmeter and tachometer.
18. Connect the standard wire to the generator output «IN».
19. Connect a wire to the negative plug of the storage battery.