Until about the end of 1991, some AUDI 80 models were equipped with a 65-A alternator. They were replaced by 90-A alternators. With special equipment, 110 and 120-A alternators can be installed. The alternator produces a voltage of 14 V when the on-board network needs 12 V. Due to this difference, the battery is charged.
The generator drive by a V-belt or V-belt from the crankshaft belt pulley is designed so that even when the engine is idling, the generator can generate current at ⅔ of its maximum capacity (see illustrations 4.0a).
Illustration 4.0b shows a newer model Bosch generator, which differs from the previous ones by the cover 1.2-terminal B+ (to the battery).
Since the battery can only be charged with direct current, the alternating current generated by the generator is converted into direct current by a corresponding diode rectifier. The rectifier diodes are very sensitive to high voltages. For this reason, it is necessary to observe certain precautions:
- do not disconnect or connect the wires between the battery and the generator while the generator is running. The resulting voltage peaks may damage the diodes.
- the generator must not operate with the battery disconnected.
- all connections from the generator, including the ground (-) wire, must have good contact.
- disconnect the battery when performing welding work on the body.
The crankshaft, which drives the generator, rotates depending on the road situation with a lower or higher number of revolutions. Accordingly, the crankshaft rotation, the generator produces a lower or higher current, which is unacceptable for consumers of the on-board network. For this reason, the generator is equipped with a voltage regulator that maintains the voltage from the generator within 14 V regardless of the generator rotation frequency.
There is a battery charge indicator light on the instrument panel. It has two positive contacts (+). One of them receives power from the D+ terminal of the generator (blue insulated wire), and on the second one - from terminal 15 through the multi-pin plug of the ignition switch (wire with black and blue insulation).
When the ignition is switched on, power is supplied to the indicator lamp from terminal 15. However, the generator has not yet switched on, so terminal D+ acts as "ground" (-). The indicator lamp lights up. When the engine starts, power also starts to flow from terminal D+ on the generator, and the indicator lamp goes out. An extinguished battery charge indicator lamp does not prove that the battery is being recharged. It may happen that the on-board network consumers take more from the battery than is supplied to it by the generator. This is possible if the generator is weak and is not able to recharge the battery. In such cases, the battery charge indicator lamp will not light up.
The generator requires virtually no maintenance, except for the occasional replacement of carbon contact brushes. Repairing a damaged generator at home is impossible.