Checking the voltage regulator (BMW 5 Series E34)

Connect a voltmeter to the positive and negative terminals of the battery.

Start the engine. During the starting process, the voltage may drop to 9.5 volts.

Increase the speed to 3000 rpm. The voltage should be between 13.5 and 14.5 volts. This is proof that the generator and voltage regulator are functioning properly.

Check the stability of regulation. To do this, turn on the high beam and repeat the measurement at 3000 rpm. The measured voltage should not drop by more than 0.4 volts compared to the previous measurement.

If the measurement results deviate from the specified values, take the generator to the workshop for inspection.