How an alternator works? Know Why Do you Need This Piece

As the sun gives power to everything on this planet earth and brings them to life, an alternator is something like that to your car. The majority of car users think all the power their car gets is from the battery.

However, this is a big misconception as the alternator of the car generates most of the electricity. All your battery does is just start your car and give power support when the engine is not on.

The way this system works is a bit complex, but don't worry we will explain everything about an alternator in this article, starting from its definition to how an alternator works? its classification, and so on.

What is an alternator?

An alternator is an essential part of your car that plays the main role in generating electricity. This generator's principal responsibility is to distribute electricity in your car and keep the battery charged. All the vehicles out there that have a standard internal combustion engine carry an alternator.

The size of an alternator is somewhere near a coconut. Usually, they are placed in the front part of your car's engine, and you will see a belt spinning around it.

Different Type of An Alternator

To understand how an alternator works? first of all you need to know type of an alternator. A vehicle's alternator is classified based on its uses and designs. In this part, we will try to give you a clear idea about the five types of alternators in a vehicle.

  • Automotive Alternators
  • Diesel Electric Locomotive Alternators
  • Marine Alternators
  • Brushless Alternators
  • Radio Alternators

Automotive Alternators

Automotive alternators are generally found in modern automobiles. It charges the battery and keeps the electrical system working when its engine is running. Before 1960 most of the automobiles used DC dynamo generators that had commutators.

At that time, silicon diode rectifiers were quite affordable. So, besides those automotive alternators were also widely used.

Diesel Electric Locomotive Alternators

The traction motor receives around 1,200 volts DC from the silicon diode rectifiers. And here, the traction alternator usually works as the incorporator. There are still many diesel locomotives are in service.

The generator also helps to supply head-end power or HEP. And this option needs the constant speed of the engine.

Marine Alternators

This type of alternator is quite similar to automotive alternators. They are quite good at adapting to the salt-water environment. What makes them special is, they are explosion-proof.

Brushless Alternators

The brushless alternator usually has fewer moving parts which means much lesser wear on the alternator. Alternators work by pulling air through from the rear side to the front in order to cool the internal parts.

The air carries a lot of dust inside. But when it comes to a brush alternator, you won't have to worry about the dust. So, it gives you more reliability than the others.

Radio Alternators

High-frequency alternators are generally used in radio transmission. They are famous for being used in morse code and some experiments of music and voice. These alternators were applied in producing radiofrequency current for transmitting radio signals, but the efficiency wasn't that good.

Components of An Alternator

First and foremost, to understand how does an alternator works?  You need to get acquainted with their different components.  Understanding those parts and how they operate will make things easier. So, here are they:


The pulley is the first part of an alternator, and the main responsibility of it is to keep the rotor assembly running while the engine is on. It's a bridge between the car's engine and rotor assembly.

You will find three different types of alternator pulley, such as one-way clutch pulleys, overrunning alternator decoupler pulley, and solid pulleys. Bu these types does not mean they have a different function.


The housing comes second; its main objective is to protect the inside part of the alternator. The housing can be different in two parts. The first one is front housing and the second rear. You will find the front housing near the pulley and the rear one at the opposite.


After the housing, you will get the bearings. It assists in rotor assembly rotation without any intervention. They work as the main-supporter of the rotator to make sure they are running seamlessly. The front bearing is connected to the front housing and the rear bearing in the rear housing.

Rotor Assembly

Now, it's time for the rotor assembly. The rotor assembly helps to generate a magnetic field. The stator coil will get disengaged when the rotor assembly is on the run.  And as the stator coil gets cut, it generates electricity.

Stator Assembly

Here we have the stator assembly whose main objective is to generate electric current when the rotor is being electromagnetic. Stator coil has two types of coil connection. One is the Y-type coil connection, and the other is Delta-type.


The rectifier works as a converter. It converts the alternating current to direct current when the charging process is going on. You know, the stator windings help to generate the alternating current. So, it's not useable to the majority of car electrical systems.

Voltage Regulator

You might easily recognize its function by the name. Yes, it regulates the voltage. It controls how much power needs to be distributed to the battery from the alternator to keep the charging process running fine.

The faster the rotator rotates, the more the electricity generates in the stator coil. And that's where the voltage regulator comes into play. When the alternator's output voltage gets below 14.5 V, the voltage regulator will automatically increase the current. And the voltage also starts to rise.

On the other hand, when the alternator's output voltage rises above 14.5 V, the voltage regulator will act this time by decreasing the supply of current and resulting in the voltage going down. In nowadays modern cars, the IC regulator type is found inside the alternator.

Protective Cap

In the end, we have found the protective cap. It works as a defense against the rectifier components. You will find it outside of the rear housing. Some manufacturers choose not to use a protective cap but just place all the parts inside the alternator.

After reading all the details, do you think your alternator needs a replacement? No worries, here you can know How to Change Your Car Alternator.

How Does an Alternator Work?

The electricity procedure gets started with the engine of your vehicle. In modern vehicles, alternators are run by the crankshaft of the engine. And in a typical car, you will find two windings. One is a stator, and the other the rotor.

The voltage passed through the regulator to the rotor winding, and that energizes the rotor and turns it into a magnet. The rotor gets rotated by the engine.

In the engine, the rotating rotor produces a magnetic field, and this persuades the AC in the stationary stator winding.

You need a diode to convert AC to DC in your car's electrical system. The voltage regulator takes care of the output voltage. If you have been thinking about getting an alternator for your car, here's have some of the Best Alternator Brands for Your Car.

Hopefully, from the above discussion, you understand How Does an Alternator Works. If you want to know better, focus on the paragraphs below.

Final Words

As you can see, the way a car's alternator works is quite difficult to understand. We have tried our level best to simplify it for you. So, how an alternator works?

Well, to summarize, the alternator is a power source for your car's electric system and recharges its battery. And in order to do that, the alternator needs to convert mechanical energy into electricity.

I hope this article has helped you to find all the information you needed. Thanks for your reading.

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