What is an Alternator?

An alternator is the part of a car that produces the electricity required to charge the battery and provide power for all the vehicle electrical components. The rotation of the engine is used by the alternator to generate electricity. The electricity that is generated by the alternator is an alternating current (AC). This alternating current is then transformed to a direct current (DC) for use by the vehicles electrical system.

Sometimes alternators are called generators. Alternators are the relatively modern replacement to the dynamo which was used in much earlier vehicles.

What comes with an alternator?

Alternators are generally provided with the additional parts included. These additional parts are the pulley (freewheel clutch) and the voltage regulator. This is a general statement and we would advise that you check the stock image and the parts notes to make sure.

How do I choose the correct alternator?

One of the best ways to choose the correct replacement alternator is to obtain the part number from the part that you need to replace. The part number for the alternator is generally on the side of the part while the voltage regulator on the rear of the alternator may have a different part number.

If you are unable to obtain the part number from the alternator that you need to replace then here are some factors to consider:

  • Engine code

  • ngine has start / stop function

  • Vehicle manufacture date (this is not the date the vehicle was registered but the date it was made

  • Engine number sequence (up to or after as specific number/letter

  • VIN (chassis number) sequence (up to or after as specific number/letter

What brand of alternator should I choose?

Alternators are available as either brand new parts or they can be remanufactured. Bosch are a brand that make new alternators for the original car brands and they also remake alternators to as-new quality too. Remade parts have the same warranty cover and stamp of quality as a new part does. Other brands such as Apec, HC Cargo and Napa offer long warranties which show they have confidence in their products. There can be sizeable differences in the cost for alternators so the choice of which brand to choose is often down to budget and the correct parts availability.

How can I tell my alternator needs replacing?

There are several symptoms of a failing or faulty alternator. If you are not sure if your vehicle has a faulty alternator we would suggest you speak to a qualified mechanic to receive an accurate diagnosis.

Here are some symptoms of a bad alternator:

  • Dead battery / battery will not charge

  • Battery warning light is illuminated while the engine is running

  • Electrical accessories not working properly

  • Engine will not start or stalls frequently

  • Electrical burning smell

  • Dim lights

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