A car alternator is an aluminum piece of equipment attached to a car engine's crankshaft by a drive belt. When the crankshaft begins turning after the engine is ignited, it rotates the drive belt, which forces the alternator to rotate in response. The movement of the alternator generates magnetic power that is transferred to the car's battery to power lights, windows, locks, air conditioning, the dashboard and the radio.
Alternators are encased in aluminum because the material cannot be affected by the internal magnetization of the alternator and is therefore able to disperse the high amounts of heat that are generated from within the alternator. Modern alternators also have vents on either side and internal cooling fans to further aid in the dissipation of heat. Alternators are connected to several electrical circuits throughout an engine to carry out functions such as sensing battery voltage. The horizontal rotor shaft that the drive belt attaches to is made of iron and runs through the middle of the alternator. It is surrounded by a coil of wires, which are encompassed by a larger outside cylinder that spins when the drive belt begins to move. This spinning action generates magnetic power between the two layers of the cylinder, which is then harnessed and sent through one of the electrical circuits to the battery.