Check A Car Alternator

The alternator has replaced the generator in modern cars. Most people know of it, but don’t really understand what it does. So, how do you check a car alternator to see if it is working correctly?

What is a car alternator? Well, have you ever given thought to the question of how the lights, radio and other electrical components in your car work? Most people would say the battery runs this stuff. That is true to an extent, but the alternator actually does most of the heavy lifting. This is because the alternator turns the kinetic energy produced by the engine into usable electrical charges.

The alternator works in a simple way. It sits off the side of the engine in most cars. A belt then runs from the crankshaft on the bottom of the car to alternator. This is often called a serpentine belt in modern vehicles. Regardless, the belt starts rotating when the crankshaft does. This spins the internal components of the alternator and creates an electrical charge. The current is used to charge the battery and run various electrical components.

So, how do we check a car alternator? Well, the first thing to look at is performance. The old eyeball test if you will. Alternators tend to fail slowly, not all at once. As a result, do you notice the headlights are a bit dim or you have other electrical issues? If so, the battery or alternator are usually the problem with the alternator being the prime culprit in most cases.

A more technological approach is to use a voltmeter. As the name suggests, it measure the volts of something. In this case, we want to test the alternator by check the voltage being delivered to the car battery. You can pick up a voltmeter for under $20 and often much less. You just hook it up to the battery terminals and then have somebody rev the car up. The voltmeter should show a 13.5 to 14.5 reading. If it is less, the alternator is going bad.

Noise is often another method for identifying a failing alternator. An alternator is more or less a bunch of turning parts. When the bearings that allow the turning to occur fail, a grinding noise can easily be heard. It can be hard to isolate such noises since and engine is inherently noisy. Try removing the serpentine belt. If the grinding noise goes away, you have an alternator that is failing.

How often do you need to check a car alternator? There really isn’t any scheduled check up. It is more or less one of those parts you only look at when it starts to become a problem. 

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