The Charging System

How does the VW charging system work?

A VW charging system consists of three major components:

• Generator or Alternator - A mechanical device driven by the engine belt. It produces a steady flow of electrical current on a continuing basis while the engine is running.
• Voltage Regulator - A device that monitors the state-of-charge in the battery to determine when and if more current should flow from the alternator into the battery to replace used electricity. When a battery is returned to full capacity, the regulator shuts off the flow of current from the alternator. This action occurs several times per minute.
• Battery - An electrical reservoir used to store current until it is needed to power the engine's starter motor. It provides sufficient electrical power so that the engine can reach starting RPMs. Once the engine is running, the electrical demand is supplied by the alternator alone to the coil, which continues to supply fire to the spark plugs.

A brief discussion is given at Charging.

A simple analogy for a charging system would be to compare it to a garden hose with a spray nozzle and a bucket/receptacle. Water flows through a garden hose as does the electrical current to the alternator. As long as the water/current is flowing, the hose/alternator is producing electrical current to charge the battery. The regulator, compared to the spray nozzle at the end of the hose, determines the amount of the electrical current released into the battery. The battery becomes the bucket/receptacle already filled with water. When water is removed from the bucket, the spray nozzle/regulator will open to allow water/electrical current to refill the bucket, or recharge the battery. Once the battery is completely recharged, the regulator will shut off the flow.

The system is shown schematically in the following (ignore plugs #5 and #6 :-).

Disclaimer stuff: Rob and Dave have prepared this information from their own experiences. We have not assumed any specialised mechanical knowledge, but we DO assume that anyone using these procedures has at least some basic mechanical ability.

We hope you find this information useful, but we don't take any responsibility for anything which happens to you, other people, your VW or any other property or goods resulting from your use of these procedures.

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Have fun fixing your VW - just keep them fweeming, OK?

Last revised 4 May 2004.