The generator is driven by the crankshaft through a V-belt. In diesel engines, in addition to the generator, a vacuum pump is attached to enhance the brake. The generator rotor has an excitation winding and rotates inside the fixed stator winding at a speed twice that of the engine.
The excitation current enters the rotor through carbon brushes and slip rings. Thus, a magnetic field is created in the rotor.
The position of the magnetic field in relation to the stator winding is constantly changing due to the rotation of the rotor. Due to this, an electric current is generated in the stator.
Since the battery is charged only with direct current, the alternating current of the generator is converted into direct current by a diode rectifier. The voltage regulator changes the charging current by turning the excitation current on and off according to the condition of the battery. At the same time, the regulator maintains a constant voltage of about 14 V, regardless of the engine speed.
Attention: Depending on the type, the alternator may be a replacement part. This means that when buying a repaired or new generator, the old generator can be returned and its cost will be taken into account when paying.