Most people expect modern cars to be reliable, but even dependable automobiles still suffer failures from time to time. Some components tend to fail more than others, and these repairs are often necessary on even the most reliable cars beyond a certain age. Common failure points include water pumps, ignition coils, and alternators.

A failing alternator can be an incredibly frustrating problem to deal with, but it doesn't have to leave you stranded. Learning a bit about how your alternator works and when you should consider a repair can help you avoid some of the costliest and most annoying outcomes.

What Does Your Alternator Do?

Energy comes in many forms. If you drive an internal combustion engine vehicle, your car's motor uses controlled combustion to create mechanical energy. Explosions in your car's combustion chambers move pistons, which in turn rotate a crankshaft. Although plenty more happens along the way, the motion of the driveshaft ultimately provides the force needed to turn your wheels.

Of course, there's an obvious problem with this situation: your car also contains accessories which rely on electric energy. Everything from your radio to the electronic control unit (ECU) draws on a 12-volt direct current (DC) from your car's battery. Without electricity, your car wouldn't be able to function at all.

Your alternator provides the critical bridge between your car's engine and its electrical systems. In most vehicles, a belt connected to the crankshaft pulley transfers energy to components such as the alternator. The alternator's rotation produces alternating current (hence the name), which gets converted to DC energy to charge the battery.

What Happens When Your Alternator Fails?

Your car's accessories use your battery as a large capacitor. The current delivered by the battery is smooth and consistent, whereas your engine speed affects the alternator's output. Unfortunately, your battery can't run your car for long by itself. The battery relies on constant input from the alternator to remain charged, and fully discharging a car battery may even damage it.

A failing alternator typically cannot maintain a charge at the battery. As a result, you may notice lights that dim in time with engine speed, or you may require frequent jump-starts. Eventually, the alternator won't be able to charge the battery at all, and your car will stall, usually after a few minutes of various electrical systems behaving oddly or stopping altogether.

Since a faulty alternator can leave you stranded, you should never ignore the signs of trouble. If you begin to experience any unusual electrical behavior, take your vehicle to a trusted mechanic as soon as you can. Testing an alternator is relatively simple, so most shops should be able to diagnose and repair a problem before a dead alternator leaves you on the side of the road.

For more information about auto repair, contact a local auto shop.