chapter, you will understand how these circuits work
and the adjustments and repairs required to maintain
the electrical systems in peak condition.
Learning Objective: Identify charging-circuit
components, their functions, and maintenance
The charging system performs several functions,
which are as follows:
It recharges the battery after engine cranking or
after the use of electrical accessories with the
engine turned off.
It supplies all the electricity for the vehicle when
the engine is running.
It must change output to meet different electrical
It provides a voltage output that is slightly higher
than battery voltage.
A typical charging circuit consists of the
BATTERYprovides current to energize or
excite the alternator and assists in stabilizing
initial alternator output.
ALTERNATOR or GENERATORuses
mechanical (engine) power to produce
ALTERNATOR BELTlinks the engine
crankshaft pulley with alternator/generator
pulley to drive the alternator/generator.
V O L T A G E R E G U L A T O R a m m e t e r ,
voltmeter, or warning light to inform the
operator of charging system condition.
The storage battery is the heart of the charging
circuit (fig. 2-2). It is an electrochemical device for
producing and storing electricity. A vehicle battery
has several important functions, which are as
It must operate the starting motor, ignition
system, electronic fuel injection system, and
other electrical devices for the engine during
engine cranking and starting.
It must supply ALL of the electrical power for
the vehicle when the engine is not running.
It must help the charging system provide
electricity when current demands are above the
output limit of the charging system.
Figure 2-2.Gross section of a typical storage battery.