Alternators : Similar to a generator, the alternator is the part or the car that generates the voltage that runs the automobile. Basically recharging a 12 volt battery, but also capable of the amperage nessesary for the need of the car’s electrical parts. If failure occurs, the vehicle will run out of power and eventually shut down with a dead battery. The alternator creates AC current and uses a rectifier (diodes) to change the voltage from AC to DC. A voltage regulator is required to regulate the voltage in most cases at 14.5 volts.