Connect a voltmeter to the AB contacts.
Start the engine. Voltage may drop to 8V during startup (at +20°C).
Increase engine speed to 3000 rpm. The voltage should be between 13.5 and 14.2 V. This indicates that the alternator and voltage regulator are working properly. Generator voltage (circuit voltage) must be higher than the battery voltage so that the battery ignites while the car is moving.
Check the stability of the adjustment. To do this, turn on the high beam and repeat the measurement at 3000 rpm. The measured voltage should not differ by more than 0.4 V from the previously measured value.
If the measurement results differ from the indicated values, the generator must be checked in a workshop.