Major Components of Your Car's Electrical System
Battery
Everything in your car's electrical system starts and ends with the battery. The battery performs the crucial function of turning on your car as well as powering a few accessories such as the radio or windows when the engine is off. And in order to perform all of these functions, batteries must generate electricity. This electricity is generated by lead-acid chemical reactions in the batteries' cells, giving them the name lead-acid batteries.
How do batteries work?
Lead-acid batteries consist of a hard plastic outer shell with six inner cells. Each cell generates approximately two volts, meaning most car batteries have an output of 12 volts. Each cell contains two thin metal plates, one made of lead and the other made of lead dioxide. These plates are submerged in a water-sulfuric acid solution.
The hydrogen and sulfate ions in the solution are polarized due to their attraction to the separate lead plates. While the hydrogen ions bond with the lead dioxide plate, the sulfate ions bond with the lead plate. In effect, this creates a positive and a negative side of the battery.
The electrons on the negative side of the battery can then be channeled — via the battery's negative terminal — through the car's wiring harness. The battery then powers the starter, onboard computer, and other key components in the electrical system and then completes the circuit at the positive terminal.
While the battery is efficient at providing electricity throughout your vehicle, it isn't meant to power your car's accessories for long all by itself. If you leave on your high-powered LED headlights with just battery power, for example, you'll quickly end up with a drained battery. Instead, your car relies on the alternator to keep everything powered after the engine starts.
Alternator
The alternator is the main power source for your car's electronic components while the engine is running. The radio, headlights, power windows, dashboard instruments, various sensors, and all other electrical parts of a car function because the alternator supplies them with direct current (DC) power. The alternator also performs the crucial function of charging your car battery while driving.
The alternator works by turning mechanical energy into electrical energy. When your engine is on, its crankshaft rotates and powers a drive belt connected to a pulley on the alternator. This pulley turns the alternator's rotor shaft, which spins a set of magnets around conductive coils. These spinning magnets generate alternating current (AC) around the coils — thus the name “alternator” — which is then channeled to a set of diodes in the rectifier assembly. The rectifier converts that AC power into the DC power necessary to operate your car's electrical systems and charge the battery.
While it is recommended to change out your car battery about every three years, alternators typically last much longer — anywhere between 80k and 150k miles. However, they may occasionally wear out earlier than expected. General wear and tear, heat damage, overuse, exposure to water, or frayed wires can all prematurely impair your alternator.
Starter
As its name suggests, the starter is the electrical system used to start your car when you turn your keys in the ignition switch. The starter's main function is to crank the engine just enough to turn it over. When the engine turns over, it sucks in air and fuel that is then compressed and ignited by the spark plugs to create combustion.
In essence, the starter is simply an electric motor powered by your car's battery. It works by turning electrical energy from the battery into the mechanical energy required to turn over the engine.
The starter's main components are the solenoid, starter motor, and pinion, with a few connecting elements such as return springs and an actuating arm. The solenoid is an electromagnetic device responsible for activating the starter motor and moving the pinion gear. The starter motor features a rotating shaft that spins the pinion. The pinion is a small gear used to turn the flywheel — a larger gear connected to the engine's crankshaft.
When you turn your key in the ignition, several things happen in the span of a few seconds before your INFINITI roars to life. Here's how it works:
- Turning the ignition switch completes a small circuit between the car battery and the solenoid. This allows the battery to send a low amperage electrical current to activate the solenoid.
- A current flows through the solenoid, and an electromagnet pushes an iron rod into position with two heavy contacts — completing a secondary, high-amperage current between the battery and the starter motor.
- The movement of the solenoid's electromagnet causes an actuating arm to slide the pinion into place with the engine's flywheel.
- With the secondary circuit complete, the starter motor shaft spins and creates torque on the pinion.
- The pinion, which is now meshed with the flywheel, rotates with enough torque to turn the larger flywheel gear and crank the engine. As the engine ramps up in speed and turns over, the pinion withdraws contact and the starter's job is done.
At this point, it is critically important that a driver takes the pressure off the ignition switch so as to disengage the starter motor. This is because once the engine starts, it rotates at a much higher speed than the starter motor. Maintaining contact between the engine and the starter can cause severe damage to the starter's components.
How It All Fits Together
Now that you're familiar with the three major components of your INFINITI electrical system, you can probably see how everything fits together to power your vehicle.
- When you turn your key in the ignition, the battery sends electricity to the starter.
- The starter converts that electrical power into mechanical energy to crank the engine and start combustion.
- While the engine is on, the drive belt activates the alternator's pulley system to rotate the rotor shaft and generate electricity.
- The direct current from the alternator simultaneously charges the battery and powers all of the electronic components onboard until the engine is turned off.
- Finally, with the battery topped up by the alternator, you're able to start your engine the next time you get in the car.
When one component of your electrical system is out of sync or not functioning properly, the effects can ripple throughout your entire vehicle! Help avoid an electrical system catastrophe by keeping everything maintained properly and serviced on time. Find genuine INFINITI electrical parts online or you may head to your nearest INFINITI service center for help from the experts.