Function of an Alternator
The alternator converts the mechanical energy of the engine into the electrical energy required to power the automobile. It is powered by the crankshaft which is driven by the engine. The alternator is located in the front of the engine. It generates an electric voltage between 13.5 and 14.8 volts. Most of the vehicle's electrical components take their necessary power from the alternator. The alternator also recharges the automobile's battery. A voltage regulator is included between the battery and the alternator to prevent the former from getting overcharged. The regulator shuts off once the alternator voltage goes beyond a certain level. Newer vehicles have the regulator and the alternator as a single unit, whereas in older vehicles the parts are available separately.
Understanding the Various Terminals on the Alternator
The different terminals on the back on the alternator are each meant for a specific purpose explained below:
S terminal - This terminal senses the battery voltage.
IG terminal - It switches on the voltage regulator.
L terminal - This terminal closes the circuit to the charging system warning lamp.
B terminal - This is the alternator's output terminal. It is connected to the battery.
F terminal - This terminal is the full-field bypass for the regulator. (For testing purposes only.)