Alternator Wiring And Charging System Explained

The Alternator charging system includes three main elements viz: the battery, the alternator and the regulator.

When the vehicle is moving the alternator operates in conjunction with the diesel engine of the vehicle to generate electricity. This electricity is used to charge the battery.

The alternator generates power in the form of AC, which further gets converted to DC before reaching the vehicle electrical.

Fundamentally, four wires are used for integrating the alternator output with the rest of the electrical charging system.


IG refers to the ignition input which switches ON the alternator/regulator circuit.

S is the output which connects with the regulator for the

required control of the charging current.

L wire connection is responsible for grounding the over charge warning lamp negative terminal.
The Main Parts of an Alternator

A standard alternator parts may be classified as:

Typically an alternator may contain the following sections:

A rotating field winding also called the rotor.

A fixed winding known as the stator.

A diode circuit which forms the AC bridge rectifier device.

A charging rate control circuit

known as voltage regulator.

A couple of internally installed fans for enhancing air circulation.

Normally the voltage regulator assemblies are built-in; however the earlier models might have them fitted externally.

Contrary to other models the shown type can be easily checked from the rear side of the device.

Dissecting open the alternator immediately reveals the rotor winding, enclosed within the stator winding. The rotr is primarily responsible for generating the magnetic flux to the stator winding.

When the assembly rotates, voltage is developed across the stator winding due to its reaction with the rotor magnetic field which is created through external small initial voltage, mostly from the battery which is being charged.

Article Written By Swagatam

Swagatam is a blogger at

Last updated on 25-07-2016 228 0

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