How to Tell if You Have a Faulty Alternator

If your car has a faulty alternator, the battery will not be properly recharged when the car is in use and will eventually cause the electrical system to fail. Whereas the stored charge in the battery starts a car, once the engine is running the alternator generates electricity to recharge the battery. Because there are many components to a car’s electrical system, it can be difficult to determine what is causing electrical failure. There are, however, two ways to tell if it’s the alternator.

Headlight Test

While the car is running, turn on the headlights and have a helper stand in front to observe. With the car in neutral, hit the gas pedal to rev the motor. If the headlights brighten with the increased RPMs and dim again when you take your foot off the gas, the alternator is probably faulty.

Battery Test

Put the hood up while the car is running and remove the black cable from the battery’s negative terminal. If the car engine dies, again, the alternator is probably to blame. If this were not the case, the alternator would be generating electricity enough to run the car without the battery.

These two tests can help you determine if the alternator on your vehicle is malfunctioning and needs to be replaced.