Start the engine. The voltage during the starting process may drop to 8 V (at an ambient temperature of +20°C).
Accelerate the engine to 3000 rpm. The voltage should reach 13.5 to 14.5 V. This indicates that the generator and voltage regulator are working properly. The generator voltage should be higher than the battery voltage so that the battery is charged while the vehicle is moving.
Check the stability of the adjustment. To do this, turn on the high beam and repeat the measurement at 3000 rpm. The voltage should not decrease by more than 0.4 V compared to the previous value.
If the generator voltage is too low
Check the generator electrical connections for tightness and contact quality. To do this, disconnect the wires and inspect the contact surfaces. Secure the wires to the generator.
Check all connections of the thick B+ wire from the generator to the positive terminal of the battery for tightness and quality of contact.
Check the tightness of the fit and the quality of the connection of the negative battery cable to the body, removing any traces of corrosion if necessary.
Check the wire connections on the battery.
If no defects are found, check the contact brushes or repair the generator in a workshop.