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Everything you need to know about a vehicle electrical system

In automobiles, especially the modern ones, varieties of parts are electronics and operates electrically. Well, charging systems are the basic electrical system in a vehicle which include an alternator, battery, and voltage regulator. These components are a source of power to other electrical components in the vehicle. Although voltage regulators are included in the alternator which serves as energy converters. There are tons of electrical components that rely on the electrical system of the vehicle. I guess that is our purpose here, so let dive in!

Today you’ll get to know the definition, applications, components, diagram, and working of the electrical system of a vehicle. you’ll also get to know its advantages and disadvantages.

Read more: understanding charging system in automobile engine

Definition of vehicle electrical system

car electrical systems are electrically controlled devices in a vehicle, they receive energy from the battery and return it back to the battery through the hearth. The charging system comprises of alternator and battery. This battery is used to power the starter motor helps the engine to start running while the alternator is used to charge the battery and other electrical components in the vehicle.

Apart from this charging, some automotive vehicles are designed with magneto ignition which generates power that powers a spark plug in the combustion chambers. It’s also used to power some electrical components, which help to save the battery power. Although some ignition system depends on the battery’s power.

All electrical circuits in vehicles are opened and closed either by switches or relays and fuse are used to prevent them from overloads.

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The primary use of the electrical system is to power all electrical and electronic devices in a vehicle. starting from the electrical motor, sensors, gauges, heating element, headlights, brake and trafficator lights, radio, television, air conditioning system, blowers, interior lights, refrigerator system, ignition system, etc. all these components receive power from a battery and the battery is charged by the alternator.

Note, when the engine is running all electrical devices are power with the alternator regulator’s power. This is because the alternator output is greater than the battery current when the engine is running.


Below are the functions of the vehicle electrical system:

  • The primary function of a vehicle electrical system is to generate, store, and supply electrical current to the various electrical devices in a car.
  • It operates all electrical parts/components of a vehicle.
  • Again, the vehicle electrical systems help to keep devices in good working condition as they can achieve some features.

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Components of vehicle electrical system

With the above-listed components, the major electrical parts of a vehicle include an alternator, battery, and regulator.


A magneto ignition system or high-tension magneto is an ignition system that uses magneto to create high voltage for the generation of electricity. The electricity generated is further used to run vehicles and other electrical components in the system.

The magneto is a combination of a distributor and generator built as one unit, making it different from the conventional distributor that creates spark energy without external voltage. There is a series of rotating magnets that break an electrical field, causing an electrical current in the coil’s primary windings. The current charge will then multiply when it transfers to the coil’s secondary windings. This is because there are many more times the number of windings in the secondary circuit compared with the one in the primary circuit, which then causes the multiplied charge magneto to produce a spark at a higher voltage than was created in the primary windings.

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An alternator is one of the major and inevitable parts of a vehicle charging system as it plays the best role. The electrical power that charges the battery is from the alternator, but the current produced is alternating current (AC). This AC power is immediately converted to direct current (DC) because automobiles use a 12-volt DC electrical system. A dead battery does not mean there is something wrong with it. it just that being deprive of charge, this is why alternator is also checked if a car is not starting.

Voltage Regulator:

The voltage regulator controls the alternator’s power output. Though this device is often located in the alternator, as it regulates the charging voltage that the alternator produces. It keeps the voltage between 13.5 and 14.5 volts to protect the electrical parts in the vehicle. in modern vehicles that use ECU to sense when the battery needs to be charged as controls the volt supplied. The warning lamp in the dashboard indicates something is wrong with the charging system. Often time the warning lamp is indicating a faulty alternator, resulting in an uncharged battery.


A battery is another essential component in a vehicle charging system, as it serves as a reservoir of electrical power. An engine starter motor is directly connected to the positive terminal. It helps to crank the component making the engine to start. As the engine is running, the alternator directly charges the battery. The battery can also supply power to the electrical components when the engine isn’t running.

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Diagram of a vehicle electrical system:

vehicle electrical system parts

Working principle

The working of a car electrical system is less complex and can be easily understood. All electrical devices in a vehicle are designed with switches or relay system, with the major source of energy (battery) they all receive power. So, immediately is the engine is starting the starter motor, which is an electrical device that receives power from the battery. The combustion process keeps the engine running and the alternator is used to charge the battery. This alternator’s voltage is less than the battery voltage when the engine is not running. This is because the current from the battery is used to power the vehicle loads and not the alternator. Alternators are designed with diodes that prevent current from flowing into it.

In a situation where the engine is running, the alternator’s current output is greater than the battery voltage. The current flow from the alternator to the electrical load in the vehicle and the battery to charge it up. Conventionally, an alternator’s output voltage is above the battery voltage when the engine is working.

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Now you can see vehicles electrical load are still powered even the engine is not running, as far the battery is charged enough. Though a large amount of energy is needed to power the various electrical system contained in a vehicle. Batteries can still meet reasonable electrical demands depending on their strength.

Read more: Understanding an automotive relay

Watch the video below to learn more about how a vehicle electrical system works:


Vehicle electrical systems comprise many components that include generators to electric wire harnesses to connectors and many more. In this article, we’ve seen the definition, functions, applications, components, and working of a car electrical system.

I hope you enjoyed the reading, if so, kindly comment on your fav section of this post. And please don’t forget to share. Thanks!

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