DIY Diaries: The Modern Alternator

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Gone are the days when dynamo generators were a common fixture on automobiles. Alternators have taken over, much to the benefit of the DIY-minded motorist. By virtue of being lighter and more affordable than traditional dynamos, DIY repairs to modern alternators are less complex and less costly. One fact remains constant. You'll need a considerable level of skill and lots of factual information before you're ready to take the DIY route for alternator repairs.

The Warning Signs

Problems with the alternator manifest themselves in different ways. You'll need to have a keen eye and ear on your alternator in order to identify these problems in their early stages of development. Common signs of alternator trouble may include but are not limited to the following:

• A low or an excessive rate of charging

• A non-charging alternator

• Failure by the car battery to hold charge

• A noisy alternator

A low charging rate may result from the corrosion or loosening of battery terminals. It may also result from excess resistance within the alternator's charging circuit. An excessive rate of charge may result from faulty regulators within the alternator while a non-charging alternator may have a broken belt or one that slips on a regular basis. An alternator may produce unusual noises if its pulleys are bent or loose or if its shaft bearings are defective.

The Voltage Test

Once you notice signs of alternator trouble, take corrective action immediately. The longer you drive around with a defective alternator, the greater the damage and the higher the cost of repairs or replacement. A voltage test is perhaps the easiest way to determine whether an alternator is defective. This test measures electric voltage output from the alternator, thereby allowing you to compare this output with the average output recommended for a functional alternator. Because many vehicles have a 12V battery, average electrical output from their alternators range between approximately 13V and 14V. A voltage reading that's either significantly higher or significantly lower should definitely raise concern. Here is a step-by-step guide to testing your alternator.

The Bench Test

You'll need to repair or replace an alternator that's proven to be defective through the voltage test. The bench tester helps to determine when an alternator must be replaced. Alternators that test bad on this piece of equipment are beyond repair, and they have to be replaced. This simple test could save you the cost of an unnecessary alternator replacement. Local auto service stores that specialize in electric motor repair are bound to have the bench tester.