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What Parts Make Up a Car’s Electrical System?

Technical  ·  July 8, 2020

What Parts Make Up a Car’s Electrical System?

Whenever you read about a car's 'electrical system', do you ever wonder what that term means exactly? Well, you should. For a modern vehicle to function correctly, it needs an efficient electrical system. 

The system itself is spread throughout your entire car. It enables your engine to run while also powering everything from your lights to your radio and even your USB ports (if your vehicle has them). 

Yes, a car's mechanical parts are undoubtedly crucial. Nonetheless, they still need a working electrical system to function.

In this article, we'll cover the essential parts that make up a car's electrical system. First, we'll look at the components of traditional combustion engine vehicles. Then we'll check out what modern electric and hybrid cars have that conventional cars don't. Finally, we'll list a few electrical components that both types of vehicles rely on to function efficiently.

In Combusting-Engine Vehicles


At the center of any automotive electrical system lies the battery. It is where electrical power is stored before it is distributed to wherever it's needed. One of the essential functions of the battery is to power the starter and spark plugs. Doing so allows the starter to crank the engine as the spark plugs ignite the fuel mixture in the engine to produce power.

Spark Plugs

Spark plugs are attached to the engine itself. As the name suggests, its role is to produce a spark that will start the combustion process in the combustion chamber.


A car battery doesn't hold an infinite amount of electrical power. So, it needs an alternator to keep it recharged. The alternator converts mechanical energy (powered by the car engine) back into electrical energy to be stored in the car's battery while the car engine is running.

In Electric/Hybrid Vehicles

Battery Pack

Electric and hybrid vehicles also have batteries, but their function is slightly different. Instead of just providing power to start the car, batteries are required to energise the car's electric motor throughout the entire drive. To power the motor for long periods, these vehicles need what is called 'high-traction battery packs' which can hold more power and supply it for much longer.

Electrical Motor

These vehicles also carry an electric motor. Electric cars rely only on this motor, while hybrid cars use it alongside a traditional combustion engine. Unlike combustion engines, these motors are quieter and produce little or no emissions.

Onboard Charger

When it comes to plug-in electric or hybrid vehicles, an essential component is the onboard charger. When these vehicles are connected to an external power source to recharge, the power is usually in alternating current (AC) form. This power needs to be converted to direct current (DC) power by the onboard charger so that the car's batteries can store it.


Now, let's take a quick look at the electrical components that both combustion-engine and electric/hybrid vehicles share in common.

Fuse Box

The purpose of an electrical fuse is to protect equipment from being damaged by surges in the power supply. The fuses in your home are the same as the ones in your car. Since the electrical system is connected to so many things, a lot of fuses are needed. Usually, they're all arranged in one part of the car called a fuse box. Inside the box or the car owner's manual, there's typically a diagram that tells you which fuse is connected to which electrical device.


Hidden behind all the panelling and running throughout the entire car are electrical wires. Some estimates show that a car has almost a mile worth of wiring inside it! Typically, these wires are made of copper which is a great conductor of electricity. They deliver power from the car battery to your lights, radio, and any other car part that requires electricity.

Light (Interior & Exterior)

Modern cars have lots of lights. On the exterior, there are the headlights and taillights, not to mention the indicator lights as well. Inside, however, are the cabin lights and the lights on your instrument panel. Each one of them is connected to the electrical system through the wiring mentioned earlier!

Entertainment System

I've mentioned the radio in your car quite a few times in this article already. However, let's break it down into more detail. The main radio unit at the front of the cabin isn't the only part of the entertainment system. You also have the speakers and things like a subwoofer, if your audio system is slightly more complicated. 

These days, some newer vehicles have built-in screens instead of simple radios like before. Some of these systems not only provide in-car entertainment, but they also offer things like navigation and internet surfing. Some systems also allow you to control other electrical devices through that touchscreen!


Last but not least, let's not forget about all the smaller motors that exist throughout your car. Car windows, windscreen wipers, and even trunks that automatically open and close all rely on small motors. Each of those motors is connected to the car's electrical system to function.

Final Thoughts

As you can see, the car's electrical system is connected to almost every car part imaginable. While maintaining a vehicle's mechanical parts is essential, you need to take good care of the electrical system as well. Be sure to pay very close attention to the parts that generate and store electrical power, like your battery and alternator, or onboard charger (for electric cars). 

If some of these parts fail, your vehicle might not be able to start at all. You may want to read about the common electrical problems in cars and how to troubleshooting them. Feel free to visit our website, browse its content, and give its free Parts Request tool a try!

By Ray Hasbollah

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