Learning the basics of the automotive starting and charging systems is good for both the service consultant standpoint and also just basic general knowledge for yourself. A lot of your customers will have these basic understandings so interpretation is not as important. Automotive systems operate on DC (Direct Current). The starting & charging system consists of the generator, voltage regulator, starter, battery and associated cables and harnesses.
The battery is a 12-volt lead-acid type. The electrolyte (the liquid in the battery) is composed of sulfuric acid and distilled water. The electrolyte reacts with the plates in the battery to produce an electrical current when a circuit is complete. Battery electrolyte can produce serious burns. When charging, batteries give off hydrogen and oxygen gas, a very explosive combination. Batteries should always be handled with care. Batteries are available in different physical sizes with terminal posts in different locations; they also come with different cranking amp ratings, as different vehicles have different battery requirements.
The generator’s function is to keep the battery charged and to provide electrical current for the various systems throughout the vehicle. Most of today’s generators are compact, self-contained units with built in voltage regulators and rectifiers. A generator produces alternating current that has to be rectified and regulated to as much as 14.6 volts DC for the vehicle’s electrical system. It is usually bolted to the front of the engine and driven by a belt.
The starter’s function is to crank the engine over so it can be started. It is powered by the car’s battery and consists of the solenoid switch, drive unit armature and housing. The starter is usually located on the underside of the engine. The starter’s pinion gear is engaged with the gear around the outside of the flywheel. The starter must turn the engine over fast enough for it to start. As soon as the engine is turning faster than the starter, the starter gear is pulled out of the way.