Lesson 1/Learning Event 1
Wheeled vehicles contain a generating system that keeps the batteries at the proper operating point
and assists the batteries in the job they have to do. The generating system, in conjunction with the
batteries, produces the electrical current needed to operate all electrical components in the vehicle.
A generator is an electromagnetic device that changes mechanical energy (from the engine) into
electrical energy. The automotive generator restores to the battery the current that was used to
crank the engine (recharges the battery). It also supplies current to carry the electric load of lights,
ignition, radio, and so forth. Most generators are mounted on the engine block in such a way that
the engine fan belt drives the generator.
DIRECT CURRENT GENERATOR
Principles
In a previous lesson on magnetism, we learned that when a conductor (wire) is moved through a
magnetic field, current will flow in the conductor, if the two ends of the conductor are connected
to complete the circuit. This current continues to flow in some direction as long as the conductor
moves down. Current changes its direction of flow when the conductor is moved upward. This
effect is sometimes called magnetic induction, because the electricity is induced by magnetism.
To get magnetic induction, we must have three things: a magnetic field, a conductor (complete
circuit), and motion or movement between the magnetic field and the conductor.
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