By

Automotive Electrical Systems

Automotive electrical systems are the life-blood of vehicles. Anyone who has ever experienced the frustration of a dead battery understands how important electricity is to automobile operation. As automotive technology has evolved, the systems that utilize electricity have become more complex. Because so many automotive components are dependent on electricity, the demand for specialized electrical skills has also been on the rise. All technicians should have a basic understanding of the components of automotive electrical systems.


There are numerous details involved in the technical and practical aspects of an electrical system. In order to develop a comprehensive understanding of this system, it is important to start with the basics and gradually learn about how other systems utilize the electrical current. The foundational components of the electrical system include the battery, alternator, starter, and connectors. Once we have developed a general understanding of these core components, it will be much easier to conceptualize their role in the overall functioning of a vehicle.

The Battery

The heart of all automotive electrical systems is the battery. This component is responsible for storing the electricity that will be used to start the engine and operate all of the electrical accessories contained within the vehicle. Batteries are commonly referred to as SLI because they are designed to provide electricity to the starter, lighting, and ignition systems. The standard battery is made up of six galvanic cells that produce 2.1 volts each for a total of 12.6 volts.

Most batteries contain lead plates that have been submerged in a mixture of sulfuric acid and water. The chemical reaction that results from this design emits electrons that produce an electrical current. The battery can be recharged by reversing the chemical reaction, but all batteries lose their charge over time due to normal breakdown. When the battery dies, it is important to check its voltage using a Volt Ohm Meter. This will give you a better idea of whether or not the battery is the source of the problem or if you need to investigate the possibility that either the starter or alternator have stopped working.

The Alternator

Automotive Electrical Systems #1Automotive electrical systems require an alternator in order to maintain the charge in the battery and run the electrical system while the vehicle is in operation. An alternator is an electromechanical device that transforms mechanical energy into alternating electrical current. The concept behind the alternator is also used in power stations to convert a wide variety of mechanical forces into electricity. Some common examples include wind and water energy that is converted through the use of turbines.

In the automotive industry, the alternator utilizes a belt system to convert the mechanical energy produced by the engine into electrical current. Because the alternating current produced cannot be stored in the battery, it is converted to direct current by a diode bridge or rectifier. It is worth noting that the alternator is not in constant operation while the engine is running. In fact, its operation fluctuates to meet the demands of the vehicle. The primary purpose of the alternator is to maintain the voltage level of the automobile and it should really only be operating about half of the time. It is important to understand that the alternator is stressed by many of the electrical components of a vehicle and a dead battery may actually be an indication that the alternator is no longer working.

The Starter

This component is one of the most important pieces of automotive electrical systems because it initiates the combustion process within the cylinders. The starter is a motor that uses the flywheel to turn the crankshaft. This process creates compression in the cylinders which in turn allows the engine to operate. Since the starter is the largest consumer of electricity, it receives current directly from the battery. This current is regulated by the key-operated switch within the cab of the vehicle. Starters tend to last for awhile and are usually not the source of a malfunction.

The Connectors


Cables and connectors are a vital part of all automotive electrical systems because they allow the electrical current to flow from one component to the next. While most people are quick to attribute a malfunction to one of the primary electrical components mentioned above, they often fail to realize that the problem could just as easily be the result of a bad connection. In fact, many problems start as the result of a poor electrical connection. This can be the result of a connection becoming loose or because corrosion has built-up on the battery.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>