Pic. 19.3. Connecting wires to the generator when checking the voltage drop on the wire connecting the battery to the generator
1. Check the following items before testing:
- generator status;
- alternator drive belt tension;
- burnable fusible link:
- no abnormal noise from the generator when the engine is running.
2. Turn off the ignition.
3. Disconnect a wire from the negative plug of the storage battery.
4. Disconnect the wire from the generator B output terminal and connect a 0-100A DC ammeter between terminal B and the disconnected generator output wire. Connect the ammeter's positive lead to terminal B and the negative lead to the disconnected output wire.
5. Connect a digital voltmeter to the B terminal of the alternator and the positive battery terminal, connect the positive voltmeter probe to terminal B and the negative probe to the positive battery terminal.
6. Connect a wire to the negative plug of the storage battery.
7. Connect a tachometer or MUT-II
8. Leave the hood open.
9. Start the engine.
10. Increase the engine speed to 2,500 min-1, turn on the headlights and other lamps and, adjust the load of the generator so that the ammeter shows a current value of a little more than 30 A.
Read the readings on the voltmeter, while it should show a voltage of no more than 0.3 V.
Note. If the alternator output current is large and the value displayed on the ammeter does not decrease to 30 A, set the current consumption to 40 A. Read the reading on the voltmeter, while it should show a voltage of no more than 0.4 V.
11. If the voltage shown by the voltmeter is more than the maximum allowable, then the wire is damaged or it is not securely connected to the terminal B of the generator and the battery. Check that the wire is securely connected to the terminals, and also make sure that the wire insulation is not melted from overheating.
12. Move the engine to idle.
13. Turn off all consumers of electrical energy and the engine.
14. Disconnect the tachometer or MUT-II.
15. Disconnect a wire from the negative plug of the storage battery.
16. Disconnect the ammeter and voltmeter.
17. Connect the generator output wire to the generator terminal B.
18. Connect a wire to the negative plug of the storage battery.