1. Before starting the test, check:
- generator installation;
- battery;
- alternator drive belt tension;
- fusible insert;
- the absence of extraneous noise from the generator when the engine is running.
2. Turn off the ignition.
Attention! The battery should be slightly discharged. The load generated by a fully charged battery is insufficient to accurately perform this test.
3. Disconnect a wire from the negative plug of the storage battery.
Pic. 9.2. Generator recoil current test circuit: 1 - rechargeable battery; 2 - ignition switch; 3 – a control lamp of a discharge of the accumulator battery; 4 - generator relay; 5 - voltmeter; 6 - ammeter; 7 - load
4. Disconnect the wire from the terminal «IN» generator. Connect wire from «+» ammeter (direct current) with measuring range 0–100 A to output «IN» generator, and then the wire from «–» ammeter to the wire disconnected from the output «IN» generator (pic. 9.2).
Attention! Do not use clips (type «crocodile») when connected to an electrical circuit. Tighten the connections with bolts and nuts. Otherwise, if the connection is bad (when using clamps of the type «crocodile») a serious malfunction or accident may occur due to high current.
Attention! It is recommended to use an ammeter with an inductive type sensor («current clamp»), which allows you to measure the current without disconnecting the wire from the output «B» generator.
5. Connect the wire from «+» voltmeter with a scale of 0-20 V to the output «IN» generator, and the wire from «–» voltmeter to «mass».
6. Connect a tachometer.
7. Connect the wire disconnected earlier to the negative plug of the storage battery.
8. Leave the hood open.
9. Check up the pressure shown by the voltmeter. It must be equal to the battery voltage.
Attention! If the voltmeter shows 0 V, then the probable cause is an open circuit (including fusible insert) between output «B» alternator and positive battery terminal.
10. Under the steering light switch, turn on the headlights and then start the engine.
11. Immediately after turning on the high beam headlights and turning on the heater fan at maximum speed, increase the engine speed to 2500 min-1 and read the maximum value of the generator output current (indicated by an ammeter).
The maximum allowable value is 70% of the rated output current.
Since, after starting the engine, the current generated by the generator drops rapidly, the test must be performed as soon as possible in order to have time to measure the maximum value of the recoil current.
The value of the recoil current will depend on the electrical load and the temperature of the generator case.
If during the test the electrical load is small, then the specified value of the generator output current will not be reached, despite the fact that the generator is in good condition. In such cases, to increase the electrical load (to discharge the battery) turn on the high beam headlights for a while or connect the exterior lighting of another car, then recheck.
The indicated value of the generator output current may also not be obtained as a result of overheating of the generator case or too high ambient temperature. In such cases, let the generator cool down and retest.
The ammeter reading must be above the maximum allowable value. If the ammeter reading is below the limit value and the output circuit «B» generator is working, then remove the generator from the car and test it on the stand.
12. After checking, let the engine idle.
13. Turn off the ignition.
14. Disconnect a wire from the negative plug of the storage battery.
15. Disconnect the ammeter, voltmeter and tachometer.
16. Connect the standard wire to the generator output «B».
17. Connect a negative wire to the storage battery.