The electrical charging system in your vehicle is generally made up of three major components: the battery, voltage regulator, and alternator. The battery and alternator will work together to generate power for the electrical components of a vehicle. Alternators are generally found near the front of the engine. They are driven by the crankshaft, which converts the up and down motion of the pistons into a circular movement. When this movement turns the components of the alternator it produces power through electromagnetism.
Alternators are usually small and lightweight. Most alternators are constructed using an aluminum outer housing since lightweight metal does not magnetize. Aluminum also dissipates the tremendous heat generated by producing the electrical power. If you look closely at an alternator, you will also see vents on the front and back also for relieving heat. A pulley is attached to the rotor shaft on the front of the alternator. When the engine is running, the crankshaft turns the drive belt, which spins the pulley to turn the rotor shaft. The alternator transfers this mechanical energy from the engine into electrical power for the vehicle.
If your alternator is not functioning, the electrical components of your vehicle will quickly drain your battery. Since automobiles cannot properly function without the electrical system, this can be a big issue. Alternators have moving parts, get dirty, and are subject to stress from the drastic temperature changes. All of these causes can make the internal parts gradually wear out. The most common is bearing failure. The needle bearings allow the rotor to spin freely to produce electricity. When these fail, the alternator will not work efficiently and can completely seize up. This failure will normally cause a loud grinding noise.
Older vehicles with generators tend to require much more maintenance than newer models, but there’s no standard rule for how long an alternator will last. Generally, alternators are less expensive to replace than many other parts of the vehicle. If there are any issues you notice, make sure to bring the vehicle at the first sign of them. Any odd noises or odd smells you notice will mean at least one part will need maintenance done to it.