Checking the generator voltage (Mercedes-Benz A-Class W168)

1. Connect the voltmeter to the battery terminals.

2. Start the engine. When starting, the voltage may drop to 8 volts (at an ambient temperature of +20°C).

3. Increase the engine speed to 3000 rpm. The voltage should be between 13 and 14.5 volts. This proves that the generator and voltage regulator are working.

Generator voltage (on-board voltage) must be higher than the battery voltage so that it can be recharged while the vehicle is in use.

4. Check the stability of the voltage regulator. To do this, turn on the high beam and repeat the measurement at an engine speed of 3000 rpm. The obtained voltage value should not exceed the previous value by more than 0.4 V.

If the values obtained during measurement are outside the nominal values, check the generator in a workshop.