What Is An Alternator And Why Is It Important?

The alternator is the heart of a vehicle's electrical system. It provides the voltage necessary to charge the battery and keep everything powered while the vehicle is running. The engine can’t start without a charged battery to turn the starter motor. The engine can’t run without air, fuel, and spark required for combustion. Electricity is needed to deliver fuel into the engine through a fuel pump and fuel injectors and to fire the spark plugs. Are you looking for a new Alternator? Let us help you find the correct new or remanufactured OEM alternator for your vehicle.

How An Alternator Works

Ford alternator removal

Image Credit: FordTechMakuloco

The alternator generates electricity by converting mechanical energy from the engine into electrical energy. It’s attached to the engine and operates with a belt-driven pulley. A rubber serpentine belt connects the engine crankshaft pulley to the alternator pulley. While the engine is running, the crankshaft pulley rotates the belt and turns the alternator pulley. As the alternator pulley turns, it spins a rotor with magnets around a coil that generates an electrical field.

The alternator generates AC current, but vehicle electrical systems require DC current. The AC current passes through a rectifier where it is converted to DC current before it is sent to the battery. The battery stores electricity needed to start the vehicle and operate accessories when the engine is not running. On-board computers also need a low-level current to maintain a sleep state while the vehicle is off. When the ignition key is turned on, the computers must wake quickly and communicate with each other over a datalink network called a Controller Area Network (CAN).

Symptoms Of An Alternator Failure

There are several indications that an alternator is not working properly:

  • Difficulty starting the vehicle
  • Stalling vehicle
  • Malfunctioning accessories
  • Noises from the alternator
  • Battery warning light

Some symptoms may be caused only by the battery failing to hold a charge. Incorrect drive belt tension can also cause an alternator not to operate properly. It’s important to have a complete charging system test performed. This will determine if the alternator is not charging correctly, or if the battery is not holding a charge. Sometimes a malfunctioning alternator can damage the battery cells. A voltage regulator inside the alternator maintains the required voltage to charge the battery and operate the vehicle’s electrical system. If the alternator overcharges the battery, the battery cells can quickly overheat and deteriorate. In this situation, both the alternator and the battery would need to be replaced.

Buying The Right Alternator

OEM ford alternator

A replacement alternator must be of the same design and specifications as the original unit. Alternators vary in design and voltage output ratings. The wrong alternator may fit correctly but could have the incorrect voltage output, the wrong sized pulley, or the wrong type of connector. Do you have more questions about alternators? Can’t find what you need? Feel free to contact us so we can help.

Not sure if an OEM alternator is right for you? Learn more about OEM vs. aftermarket alternators here.