If you have a car, it would certainly have an alternator. It is a generator that keeps producing regular current to keep the battery charged when the engine is running. Without Alternators, the battery would die out in a few minutes, as it has to provide the current required for generating the spark needed for running the engine. So, it is the car alternator that keeps that engine running, even if you think that fuel and air are most important.
The typical output of a car alternator is 14 V, even if your car battery has an output of 12V. This is required so that the alternator provides more than necessary voltage to keep the battery fully charged. The mechanism used inside the alternator is the rotation of magnetic field for producing alternating current (AC). Then, a diode bridge converts the AC into direct current (DC), which is used by the battery. The voltage is stabilized by using a voltage regulator. Even if the engine is on and the vehicle not moving, the alternator would keep producing current.
There are 3 main parts of the Alternators. They are the Stator, the Rotor and the Diode plus Voltage Regulator. The alternator belt rotates the pulley, which further puts the rotor into motion at an extremely fast speed. There are one or more magnets in the rotor, enveloped in a twine of copper wire, inside with it keeps spinning. The copper wires are called the Stator. As already mentioned, the job of the diode is to convert the AC into DC.
It is the voltage regulator, another component inside the alternators that would do the job of transforming the irregular voltage into a constant stream. It is only in the new Alternators that these regulators are found built-in. But, in the older models, the voltage regulators were fixed somewhere under the hood and connected with the system. The main function of this component is to protect the battery. It would cut-off the current to the battery if the voltage crosses 14.5 volts or when the battery is charged. The current is supplied again to the battery when it starts getting used.
Alternators require regulate maintenance because the internal components are constantly in a state of friction. However, the alternator is easy to maintain. You can consider it to be an issue with the alternator if the headlights turn dim and the electrical accessories also have problems. If any such problem occurs, the first thing to do would be to check the 'ALT' light on the front panel. If it is lighted, it would be a clear signal that the alternator's output voltage is declined.
Before you test the alternator further, it would be best to check the output voltage from the battery terminals. Use a digital multi-meter for this task, and you would be able to find whether it is working or dead. If it is delivering its normal 12 volt output, then check the output from the alternator. If it is 14 volts, then check for consistency by putting some load on it. If the voltage drops, and doesn't remain constant, then it needs repair. If the voltage is below 14 volts, then it is a clear sign that one of the alternator's internal stages has some problem.
Loose wiring is one of the most common problems that hinders the working of electrical components. Make sure that you have also checked for any type of loose connections that may hamper the working of the car alternator. Chances are that fixing such loose ends is all that is required for restoring the function of this device. The component may even be generating low voltage because of a loose or worn out belt. You can check it by opening the hood and looking at the condition of the belt. Make sure that it is neither worn out or it has lost its tension. If it has any such problems, it must be replaced.
If it is not possible for your to find out the real cause of the problem, you must seek the assistance of a mechanic. They can check the alternator and find out the main reason for the fault. However, at the same time, a car owner must always have a clear understanding of the different problems associated with his vehicle. If you know the right solutions to different problems, you can do the necessary when the mechanic is not available.