subject: Understanding The Job Of Your Vehicle's Alternator [print this page] Despite what many people assume, their car's battery receives plenty of help in providing the power needed to crank their engine, and operate their vehicle. Much of this help comes from the alternator. Often billed as the hardest-working part in your car, this component is responsible for making sure the battery maintains a sufficient charge while you're on the road. In its absence, the battery would quickly die.
We'll describe the alternator's operation below. We'll begin by explaining its job in more detail, and introducing you to the key pieces inside the assembly. You'll also learn about common problems people experience with this component as well as how to make it last as long as possible.
Maintaining A Proper Range Of Volts
Not only is it important that your alternator generate voltage for your battery, but it must do so within a limited range. That range is between 13.5 and 14.5 volts. An area of confusion for many people is that the charging system of automobiles is known as a 12-volt system. This reflects the voltage required to operate the headlights, defroster, windshield wipers, and other electrical components. Given this, why does your alternator need to generate more than 12 volts? The reason is due to the battery's resistance.
When your engine is on, your battery does not supply power to the electrical systems. All of the current is produced by the alternator, which simultaneously charges the battery. When you turn your engine off, the opposite effect occurs. All of the current flows from the battery to systems that retain memory; none comes from the alternator.
Individual Components Of An Alternator
Inside your alternator, you'll find a rotor and stator. The rotor is equipped with electrical coils on its ends. It spins on an axis, its rotation driven by a belt connected to your engine. Stator windings (groups of copper coils) line the inside of the alternator, remaining stationary as the rotor spins. The rotor's rotation brings its coils in line with the stator windings.
As the coils of the rotor approach the coils of the stator, they trigger a current. This current is AC voltage that travels toward your battery. The problem here is that your battery needs DC voltage. Diodes convert the current from AC to DC.
Before the current reaches the battery, it must be within the range mentioned earlier: between 13.5 and 14.5 volts. Moreover, it needs to vary depending on the battery's charge. This is the responsibility of your voltage regulator. It regulates the current that arrives at the battery, and modifies it according to the battery's charge. This helps ensure the battery maintains sufficient voltage to crank the engine, and power the electrical components that retain memory.
Potential Problems
The most common problem people experience with their cars' alternators is that they undercharge the battery. When this happens, you might notice your headlights dimming, and other electrical components behaving oddly. You may also hear your alternator making a distinct ticking sound, similar to the sound a woodpecker might make tapping on a tree. The only solution at this point is to replace the component.
Another problem is that the alternator may overcharge the system. Here, too, components that rely on the voltage may act strangely, or stop working. For example, both of your headlights might burn out simultaneously. As before, the solution is to install a replacement.
The most effective way to prolong the life of your alternator is to periodically check the connections between the battery posts and cables. If you notice corrosion on the posts, clean it off. If the cables are positioned loosely, tighten them.
Assuming your charging system is working properly, your alternator may last over 100,000 miles. You may never need to replace it. If the component fails, however, install an OEM-certified replacement to avoid problems down the road.
