Attention! When working with the generator, observe the following requirements:
- do not remove the battery, generator and voltage regulator with the ignition key inserted;
- mark the wires to avoid mixing them up during installation;
- do not remove the generator when installed (connected) AB;
- turn off the battery when carrying out welding work.
The model of the generator used in the BMW X5 series with the E53 body depends on its engine configuration. All generators are three-phase alternating current with a built-in rectifier block on nine valves (six main rectifier diodes and three additional), rated output current of 75 A or 150 A and an electronic voltage regulator with an adjustment range of 13.5–14.1 V. The design features of the generator and its power depend on the engine model (Fig. 16.2).
The generator is driven by a crankshaft using a belt. The rotor with the excitation winding rotates inside the stationary stator winding. Excitation current passes through the excitation winding using carbon brushes and slip rings. This creates a magnetic field. The magnetic field constantly changes its position relative to the stator winding in accordance with the rotor speed. Two slip rings are pressed onto the rotor shaft. The generator is cooled through the holes in the covers, air is supplied by a blade fan mounted on the drive pulley, or has liquid cooling ("M57" and "M62"). The rotation frequency of the generator rotor is twice the rotation frequency of the engine crankshaft. However, since the AB is charged only by direct current, the generator has a built-in rectifier and voltage regulator.
The generators are equipped with electronic voltage regulators of type 5 PK 1815 or 5K 1592 with an output voltage of about 14.3 V. The voltage regulator changes the charging current by switching on / off the excitation current, in accordance with the degree of charge of the battery.
The charging current supply to the battery (M54) begins at a terminal voltage of 14 V and a steady state of 1000 min⁻¹. The charging current of the generator, at a terminal voltage of 14 V and a rotor shaft rotation frequency of:
- at 1400 min⁻¹ –20 A;
- at 2100 min⁻¹ – 50 A;
- at 6000 min⁻¹