Why Did My Car’s New Alternator Fail?

by | Aug 23, 2016 | Auto Questions, Car Problems & Repairs

When people have their car alternator replaced, the expectation is that the repair will last at least as long as the expected life of the new alternator, four to five years or anywhere from 50,000 to 100,000 miles. Plus, like many auto repairs, replacing an alternator is not cheap. A quick check online shows the cost to replace an alternator in the Columbia, Maryland market on a Subaru Outback, for example, can range from $345 to $585.  It makes sense that when a new alternator fails after only a few months, any car owner would want to know why!

Unfortunately, not that long ago, a BA Auto Care customer was asking us why their car’s new alternator, that was just replaced, failed.  In this instance, the customer had replaced their alternator at another auto repair shop because they experienced problems when they were out of town.  Unfortunately, the auto shop performing the repair did not replace the failed alternator with a new one; they didn’t even use a quality remanufactured part.  Instead, the repair had been performed with a cheap, rebuilt part.  So several weeks later, here was the customer, at our shop, with a failed alternator.

We ended up replacing the alternator on our customer’s Subaru, but we also found that the battery was marginal. The alternator was running at 30 amps all the time and becoming very hot!

We have found that one of the most common things missed by technicians during alternator replacement is a careful check of the battery; this is especially important for a battery more than three years old. Additionally, as a double check, the alternator output should be tested to see that it charges the battery quickly then returns to an ‘at rest’ rate of ten amps or below.

Changing the battery fixed our customer’s problem.  The new alternator performed as expected, charging quickly then settling in and keeping the new battery fully charged.

The customer’s cheap rebuilt alternator did come with a “lifetime” warranty, but who wants the inconvenience of having a job done more than once! Plus, the warranty on this cheap, rebuilt part did not cover labor. (Sidenote:  At BA Auto Care, we use quality parts sourced from the same manufacturer that the auto maker uses. Plus our warranty on major repairs covers parts and labor.)

That’s why it’s so important to get information about any place you are having your car serviced.  Are they certified?  Do they use high-quality original equipment manufacturer parts? Will the warranty cover parts and labor? These questions should be checked into even if you are out of town or on the road.  The inclination may be to drive your car or have it towed to the nearest shop, but, whenever possible, do as much research online that you can before you have your car towed to a specific shop. Most shops have websites, and the info is usually spelled out there. Avoid the #prematurefailure #fixitagainandagain blues!

1 Comment

  1. Darin Lazzaro

    Great article. Informative


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About the Author

About Brian England

Brian England, the current president of BA Auto Care (formerly British American Auto Care), got his start with an auto apprenticeship in a small town in northwest of London. He came to the U.S. in 1972 to work for a Land Rover dealer in Rockville, MD. A few years later, he started British American Auto Care with his wife, Jennifer. Brian is a big believe in preventative maintenance, and his philosophy is to encourage and educate drivers on the benefits of a regular maintenance plan.