Main Components of an Alternator

by Richard Ludwig
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An engine's alternator maintains the voltage to the car's battery, which powers the lights, heater and other accessories. It is analogous to a generator as it produces electricity through a turbine-like system. The 12-volt battery carries only enough charge to initially start the car. Without an alternator, the battery would have to be recharged manually every time you needed to restart the car. An alternator has three main components, each playing a specific role to keep the car's battery fully charged.

Rotor and Stator

The rotor and stator of an alternator are a belt-driven group of magnets inside copper wiring that creates a magnetic field. The belt is driven by a pulley connecting to the engine, allowing the rotor to spin at a high speed, creating a magnetic field. The stator then creates voltage and electricity to flow to the diode assembly. The electricity created is alternate current, or AC.

Diode Assembly

An alternator's diode assembly converts AC electricity to direct current, or DC, which is the current type used by car batteries. The diode assembly, a two-terminal system, works by only allowing the electricity created in the stator to flow in one direction.

Voltage Regulator

The voltage regulator is an alternator's surge protector. Modern voltage regulators, which are internal systems, monitor both alternator and battery voltage, adjusting the current when necessary. Older voltage regulators were externally mounted.

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