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While fuel is necessary to run your car, without electricity, it would be stuck in its tracks. Luckily, every modern vehicle is equipped with an electrical system, which provides the necessary power to get you rolling.
The electrical system is responsible for multiple applications from starting your car to powering accessories like locks, windows, and headlights. This is done using circuits that are opened and closed by switches or relays. Two of the most important components in your electrical system are the battery and the alternator. Although they serve different functions, both play an important role in keeping your system running.

So how does your battery and alternator work? What makes these components so important?


When your car is off, it's the battery that runs its electrical system. Anything you use—interior lights, power locks, stereo in auxiliary mode—is being powered by the battery while the car isn't running. Of course, the main function we think of when it comes to the battery is its role in starting the vehicle. The starter, fuel, and ignition systems receive electrical current from the battery when the vehicle is started so that those systems can create the combustion that powers the engine. If your battery fails, your car won't be able to start.

Signs of a failing battery include a dashboard indicator light illuminating, your car starting slowly, a swollen battery case, and/or smelling of sulfur. If you suspect your car's battery is failing or just want to check it as a precaution, bring it to your local Pep Boys for a full diagnosis.



Once the engine is running, it's the alternator that indirectly begins powering the car's electrical system by continuously recharging the battery. Using electromagnetism, alternators produce AC power, which then feeds through diodes that convert it to DC before sending it through a voltage regulator and to the battery. If your alternator fails, your battery can't recharge, which could eventually drain your battery completely.

Symptoms of a failing alternator include dashboard warning lights, dimming headlights, a weak battery, burnt smell, loud grinding noise, and/or malfunctioning electrical components. Those symptoms, however, are not always signs of alternator failure. If you notice any of them, bring your car to Pep Boys for a full diagnosis.

Your car's electrical system plays a large role in its ability to function properly. And it's something worth maintaining to help you prevent unexpected problems.