Understanding Your Car's Electrical System | Scott's Fort Collins Auto

Understanding Your Car’s Electrical System

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The electrical system in your car is a complex system that is made up of more than just the battery. While some parts in this system are less vital, others are extremely important to ensure functionality and the safety of you and your passengers. 

The Common Electrical System

The car’s electrical system is made up of the battery, starter, alternator, and ignition. Our cars today are made up of different systems that all work together to keep your car running and on the road. NAPA Know How explains that it would be impossible to take any one of these systems out and still have a car that drives. While you can’t specifically say the electrical system is the most important part of the car, it’s not far behind. They briefly describe how the electrical system components work:


“Electricity” refers to electron flow through a circuit where one end is positive and the other negative. To be able to power something like the car’s motor, the battery was developed using man-made chemical cells with high electric potential. Batteries, in turn, give power to:

  • Starting
  • Charging
  • Security systems
  • Lights
  • ABS
  • Computers
  • Sensors
  • Climate control
  • Onboard accessories

While the battery is usually the first thing people think about when considering how these systems work, they don’t work alone in running the system. 


Further, there are two types of electricity: 

  1. Alternating current (AC)
  2. Direct current (DC)

When batteries discharge they emit a constant direct current power in one direction, giving electricity through the positive terminal to the negative. Most car parts require this DC charge to work correctly, but it is limited because batteries will eventually give out altogether meaning there’s no power left to give. Due to this, cars also have alternators. The alternator is a small generator that can turn mechanical into electrical energy. It is driven by the engine belt and uses a small signal from the battery to energize a field current that turns a rotor inside a set of stators. Since this energy is driven by the polarity of magnetic fields, the current made as a result switches direction as the rotor spins, producing current in opposite directions, which is the AC. Alternators produce higher currents than initially supplied by the battery, so they are used to recharge the battery itself and supply power to the other electrical components. 


Most parts within the electrical system require the direct current to run. The solution to this is a set of diodes that have the job of being an electrical check valve for current leaving the alternator. Diodes only allow current to flow in one direction, so when AC goes through one side, DC comes out on the other. 

Another issue within the car’s electrical system is the fact that not all components tolerate the same amount of current strength. Therefore, the system needs voltage regulators and fuses to moderate flow and protect components that can’t handle the strength that comes from the alternator. The fuses protect circuits when placed in front of the load. 

Do I Need to Have My Car’s Electrical System Checked?

The alternator powers your air conditioner, which you might not think is the most important thing, but it also provides energy to the engine fan. It’s important to have your electrical system checked because there’s not always a clear indicator that the alternator is close to needing to be replaced. However, if you notice any of these signs, come in right away to have your alternator checked:

  • Warning light
  • Dim headlights
  • Flickering lights
  • A dead battery
  • Broken or loose connections
  • Bad belts
  • Strange sounds
  • Odd smells
  • Slow accessories
  • Regular stalling
  • Difficulty starting

Stop by Scott’s Auto & Repair

At Scott’s Auto & Repair, our techs are experts with engines of every kind. If you do need a replacement, we will talk you through what parts we recommend — all of which we carry right here in our shop! Call us to let us know you’re coming or just stop on by one of our two locations! Fort Collins: (970)-682-4202 or Loveland: (970)-541-4404.


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