Always check the following before testing:
- installation of the generator and connection of wires;
- battery;
- alternator drive belt tension;
- fusible insert;
- the absence of extraneous noise from the generator when the engine is running.
Note. The battery used for this test should be slightly discharged. The load generated by a fully charged battery is not suitable for this test to be carried out accurately.
Turn the ignition key to position «OFF».
Disconnect the wire from (-) battery terminals.
Pic. 7.23. Generator output current test circuit
Disconnect the standard wire from the output «IN» generator. Connect ammeter (DC, with a range of 0-100 A) in series between output «IN» and a regular wire disconnected from the generator. Connect (+) ammeter wire to terminal «IN» generator and then wire (–) ammeter to the standard wire disconnected from the generator (pic. 7.23).
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») serious malfunction may occur (or even an accident), caused by high current.
Note. We recommend using an ammeter with an inductive type sensor («current clamp»), which allows you to measure the current without disconnecting the standard wire from the generator.
Connect Voltmeter (with a scale of 0–20 V) between output «IN» generator and «weight». (Connect (+) voltmeter lead to terminal «IN» generator and then (–) voltmeter wire to «mass».)
Connect a control tachometer or tester.
Connect the wire to (–) battery terminal.
Leave the engine hood open.
Check that the voltage shown by the voltmeter is equal to the battery voltage.
Note. If the voltmeter shows 0 V, then either an open has occurred or the fusible link has burned out in the circuit between the output «IN» generator and (+) battery terminal.
Start the engine and turn on the headlights.
Turn on the high beam headlights and set the heater fan switch to the position «HIGH», then sharply increase the engine speed to 2500 min-1 and read the maximum value of the generator output current (indicated by an ammeter).
Limit value: 70% of the rated output current.
Note. The rated output current is specified in table 7.1.
Since after starting the engine, the current generated by the battery drops rapidly, the procedure for increasing the engine speed must be performed as quickly as possible in order to have time to measure the maximum value of the generator output current.
The value of the recoil current will depend on the electrical load and the temperature of the generator housing.
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 (in order to discharge the battery) turn on the high beam headlights for a while with the engine off and then check again.
The indicated value of the generator output current may also not be obtained as a result of overheating of the generator case or at too high an ambient temperature. In such cases, let the generator cool down and retest.
The ammeter reading must be above the limit value. If the ammeter reading is below the limit value, and the output circuit «B» generator is serviceable, then remove the generator from the car and check it on the stand.
After checking, let the engine idle.
Turn the ignition key to position «OFF».
Disconnect the control tachometer or tester.
Disconnect the wire from (–) battery terminals.
Remove the ammeter and voltmeter.
Connect the standard wire to the output «IN» generator.
Connect the wire to (–) battery terminal.