Wheaton BP
(301) 949-0308



When the automotive industry was in its infancy, it used electricity only to ignite the fuel inside the engine. By the late 1920's, the electric starter replaced the hand crank, electric headlights made acetylene lamps obsolete and the sound of the electric horn drowned out the toot of the hand operated air horn. Today, a car uses an extensive electrical system just to produce, store, and distribute all the electricity it requires to allow it to run smoothly and offer the driver the comfort now expected in a vehicle.

The Electrical System

Electrical System

The first major component in the car electrical system is the battery. The battery is used to store power for starting, and for running auxiliary devices such as clocks, radios and alarms when the engine is off. Another major component is the starter motor, which is used to start the engine. The third component is a charging device powered by the engine, known as the car alternator. This devices powers the electrical system , and charges the battery, but only when the car is running. With these basic components, the car maintains its supply of electricity. The alternator produces electricity using the rotation of the engine and delivers this electricity to the battery and maintains a full charge at all times. If the voltage produced by the alternator goes above 13.5 - 14.5 volts, the battery will be ruined very quickly. It's the job of the voltage regulator to keep the output voltage between the 13.5 - 14.5 volt range. The voltage regulator keeps the voltage at the correct level and the power level stabilized, and the fuses ensure that any minor electrical faults do not develop into major problems such as damaged components, or even worse, an electrical fire.

Many different auxiliary electrical devices are used in modern cars, such as: radios, cellular phones, rear window defrosters and electric door locks, as well as a vast array of motors powering everything from the moon roof on down.

There are some signs you can look for that will indicate a problem with the charging system. If the headlights brighten or the blower motor picks up speed when you rev the engine, you may have a weak battery. This indicates the battery may not be holding enough current to run the car and is working off the alternator. If the charge light is on dimly at idle, this could indicate a weak alternator. If all the warning lights come on while driving, this could indicate a bad diode pack in the alternator. It may or may not still be charging, but you don't know unless you have it checked. At any rate, it will need to be replaced.

If you notice a strong sulfur smell, it could indicate a bad voltage regulator. The battery acid boiling inside the battery is causing the smell. This could lead to a battery explosion so be very careful when checking it.

More about the battery

Click here to go back to our parts list.