Do you need a new Alternator? How to tell if yours is bad

alternator in a vehicle

Your alternator is a central component on any engine. The alternator is responsible for powering anything electronic on your vehicle, including the coils that fire your spark plugs (unless it’s a diesel). At Performance Automotive, Inc in San Diego, CA, we know a bad alternator when we see one - here’s how you can spot one too.

What the alternator does

The alternator takes over for powering the vehicle as soon as the vehicle starts. When the engine isn’t running, the battery is responsible for delivering electricity - once the engine starts, the alternator takes its place. A battery would run dead fairly quickly if it were solely responsible for powering everything, starting the vehicle, and running the engine. The alternator spins as the engine runs, generating power as long as the engine is going, and charging the battery in the process.

What happens when it fails

Most of the time, an alternator will either work or it won’t. Sometimes it can fail intermittently, but any time it fails to charge the battery you’ll start noticing an issue. If the alternator isn’t producing enough voltage to keep up with the demands of the vehicle, the engine and electronics will start drawing power from the battery instead. Eventually, since the battery isn’t being charged, it’ll run out of juice. Problems will manifest in a few different ways. You may notice that once the engine is shut down, there’s not enough power to start it again - if the battery is in good shape, the alternator is a likely culprit. If you notice the headlights are dim, especially when at idle or running multiple electronic components, that’s another symptom of a failing alternator. You might notice the radio or other electronics begin acting erratically, or the engine itself runs poorly, especially when you turn on high current components like the headlights or heater fan. Try turning all the electronics off and see if the vehicle performs better, especially if you need to make it off the road before the battery dies completely.

What to do about it

Diagnosing a bad alternator can be tricky without the right equipment and knowledge. Sometimes problems appear intermittently, or if it’s barely beginning to fail, it may take a long time between moments where the vehicle is running long enough to kill the battery. The best way to diagnose a bad alternator is with a multimeter - if you test across the battery leads or to the back of the alternator with the engine running, and it’s not reading well over 12v, the alternator isn’t doing its job.

Specialized equipment for testing and diagnosing an alternator makes the job even more simple and concise - a professional technician with the right tools can often tell you what’s wrong in just a minute or two. At Performance Automotive, Inc, we can diagnose and replace a bad alternator in no time, and get you reliably back on the road. Our crew wants to ensure your safety on the road, so we make sure our repairs and service guarantee reliability and quality.

No matter your repair or maintenance needs, we’ve got you covered. For the repair and service shop in San Diego, CA, call or stop by Performance Automotive, Inc today.




Thank you for visiting Performance Automotive, Inc in San Diego, CA. Count on our automotive repair technicians to keep your car, truck, suv, or van on the roads longer and safer. Schedule your appointment today (858) 695-9644 or schedule here.

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Performance Automotive, Inc

location small7629 Carroll Rd
San Diego, CA 92121

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CALL:  (858) 695-9644

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Saturdays: 9:00 AM - 1:00 PM

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