Audi A4

since 1994 release

Manual of the car

Audi A4
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ System of an exhaust
+ Cooling system
+ Fuel tank and fuel pump
+ Air filter and channels of absorption
+ System of injection
+ Coupling
+ Transmission and main transfer
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tires
- Electrotechnical equipment
   Minus is connected to weight
   The help for orientation in the electrotechnical equipment of the car
   Connections of wires
   Central switching knot
   Support of additional relays
   Box for electronics
   Relay and control units
   Switching relay
   H-contact of the relay of unloading
   Table of the relay and control units
   Safety locks
   Table of safety locks
   + Electric circuits
   + Accumulator
   - Generator
      Generator of alternating current
      Control bulb of charging
      Tension regulator
      Self-help in work with the generator and regulator of tension
      The movement with the defective generator
      Maple and poliklinovy belt
      Check of a condition of a maple and poliklinovy belt
      Replacement of a maple and poliklinovy belt
      The belt torn maple
      Review: maple and poliklinovy belt
      The help at malfunctions
   + Starter
+ System of ignition
+ Lighting
+ Alarm equipment
+ Tools and devices
+ Heating and ventilation
+ Body details
+ Salon
Search of malfunctions
Technical characteristics


Generator of alternating current


Depending on the engine and a complete set we see the 70, 90 and 120 generators in Audi A4 And. the 70-ampere generator is serially put on cars with four-cylinder engines, the 90-ampere generator is included in the serial package of cars with six-cylinder engines and the 120-ampere generator enters a special complete set.

To determine generator power, it is necessary to multiply the specified maximum current by rated voltage in 14 V. Naprimer, 90A X 14 of V = 1260 W.

You already noticed: the generator really delivers 14 V at 12 V in onboard network. I.e. only at such small distinction in tension current can flow to the accumulator in order that to load it.

Transfer from a belt pulley of the crankshaft to a belt pulley of the generator is so chosen that on single turns about 2/3 capacities of the generator can already be made.

Handling of the generator and precautionary measures

The generator of alternating current along with the quite high power has decisive advantage: it gives current already on single turns of the engine. Besides, its graphite brushes maintain the run considerably exceeding 80 000 km. As it is clear according to the name, it makes alternating current which we cannot use in the car as the accumulator can keep only a direct current, of course. Therefore in the generator three diode rectifiers which will transform alternating current to the pulsing direct current are built in. These diodes are sensitive to the high tension and therefore you have to consider the next moments:


  1. At the working engine it is impossible neither to remove, nor to connect any wire between the accumulator and the generator. At the expense of it tension (tension peaks) can sharply increase and "to overheat" the diode.
  2. The generator of alternating current should not work without correctly connected and serviceable accumulator. The accumulator serves for the generator somewhat as the buffer at tension peaks.
  3. All connections of wires between the generator of alternating current, the accumulator and metal of a body or the block of the engine (weight) have to be strong. Even the shaking contact can lead to power surges.
  4. At the accelerated accumulator charging (it is impossible to use for charging in house conditions) and during the welding works on a body both wires have to be disconnected from the accumulator not to damage generator diodes.

In models with four-cylinder engines the generator (2) settles down at the left ahead near the engine and is available from above. Figure "1" showed the top fixing bolt.

Type of the six-cylinder engine from below. The generator (2) is placed on the right below about the engine. For cooling of the generator the air channel (1) is connected (here it is dismantled for the sake of presentation of the image).