How a Car Alternator Works

You may think it’s not important to understand the mechanics of your vehicle, but part of being a responsible driver is knowing how your car functions. Together with the battery and the voltage regulator, your car alternator plays a crucial role in your vehicle’s charging system. By converting chemical energy to electrical energy, the alternator powers your car’s electrical system and charges the battery. Some electric components that get energy from the alternator include the interior and exterior lights and the car’s instrument panel. At Infinity Insurance Agency, Inc. (IIA) we may not be experts in alternators, but we understand that along with insurance, proper car care and maintenance are integral parts of car ownership. Follow along as we walk you through the critical role of the alternator in keeping your battery charged and how to stay on top of alternator maintenance.  

What is an alternator?  

What is an alternator? Simply put, an alternator is a generator that is used for the sole purpose of distributing electricity to the car and recharging the battery. (RealPars) While many people mistakenly believe the car’s battery is responsible for powering its electrical systems it is the alternator that provides energy while the vehicle is running. The alternator’s name is coined from the phrase ‘alternating current’ or AC. Usually, an alternator is around the size of a coconut and can be found mounted to the front of the car’s engine by a rubber belt.  

The alternator parts are as follows:  

• Rotor - this is a cylindrical piece of the alternator which is surrounded by magnets. It spins inside of the stator, which holds a fixed set of conductive copper wiring. This movement of the magnets over the wiring is what ultimately creates electricity in your vehicle.  
• Stator - the rotor and stator work together to create electricity. The stator is attached to the alternator’s shell and is immobile. It consists of an outer frame, core, and winding.  
• Diode rectifier - this part is responsible for converting the voltage from the alternator into a form of energy that can be used by the battery to recharge.  
• Voltage regulator - this piece of the alternator oversees the power made and monitors the level of voltage that is output to the battery and delivers power to the rest of the car.  
• Cooling fan - alternators give off a lot of heat, so the fan is crucial in aiding in the cooling process. Please note newer alternators tend to have internal cooling fans, whereas older versions usually have external fan blades.  

How does an alternator function?  

An alternator’s main purpose is to turn mechanical energy into electrical energy. This process begins in the engine, where in most vehicles’ alternators are driven by the engine’s crankshaft through a serpentine belt. The movement from the drive belt spins the alternator’s rotor at a high speed within the stator. Through this movement, electrical energy is made. Thanks to the placement of magnets surrounding the rotor, as they pass over the copper wiring in the stator a magnetic field is created. This field then produces voltage which can be captured by the stator and eventually reaches the voltage regulator. Finally, the regulator can disperse electricity to the vehicle and manage the amount of energy delivered to the battery. (RealPars)

Charging the car battery  

Before your car can utilize the energy coming from the alternator it must be converted into a usable format. Since alternators output alternating currents (AC electricity) and car batteries operate on a one-way direct current (DC electricity), before the energy can be used, the power intended for the car battery must go through the diode rectifier. (HowStuffWorks.com) Here the power is transformed into DC and then can go on to be used by the battery to charge.  

What does the alternator power?  

In addition to providing invaluable support to your car’s battery, the alternator also provides power to your vehicle’s electrical systems including:  

• Headlights and interior lights  
• Electric steering  
• Power windows and seats  
• AC and heating  
• Windshield wipers  
• Heated seats  
• Dashboard instruments  
• Radio and entertainment systems  

Making sure all of these components are functioning properly and keeping up with regular vehicle maintenance can be an essential factor in the longevity of your vehicle.  

Signs of a failing alternator  

You can detect signs of a failing alternator by observing a plethora of symptoms, according to HowStuffWorks.com. If you suspect your alternator may be malfunctioning, your first stop should be to check your car’s dashboard. If you see your car’s battery warning light turn on, this could be a sign of a failing alternator. Try to shut off all unnecessary electrical components and call for help.  

Other signs of a malfunctioning alternator can include:  

• Dimming lights - this can include both the dimming of your car’s headlights and dashboard  
• Grinding noises - alternators utilize various parts to keep moving, such as belts and pulleys. When these parts start to wear down, they can produce odd whining or grinding noises.  
• Weird smells - the smell of burning rubber may mean there is an alternator issue as this smell can occur when a misaligned component causes friction and heats the belt.  
• Electrical failures - since your alternator powers electrical functions in your car, slow power windows or other electrical malfunctions could be signs of alternator failure.  

Please note that this is not an exhaustive list of failing alternator symptoms, and IIA is not an expert in alternator issues. If you believe your car’s battery is dead or suspect alternator issues, bring your car to a trusted mechanic for a full electrical system inspection.  

Causes of alternator failure  

Throughout its life, an alternator will sustain a certain amount of natural wear and tear. However, additional factors such as an excess of heat, vibration, or surges in electrical energy can shorten an alternator’s shelf life. While an alternator should last the lifetime of your car, a loose or broken belt, overuse, exposure to water, or frayed wires can all contribute to a shorter alternator lifespan, according to HowStuffWorks.com. IIA encourages the use of a licensed mechanic when dealing with alternator repairs or issues.

Your car’s electrical system paves the way for smooth, comfortable driving. Without a properly functioning alternator, things can easily go awry. Stick to a regular maintenance schedule and always be on the lookout for symptoms of a failing alternator. If you suspect an issue, see your trusted mechanic and wait for a professional diagnosis.  

Besides regular car maintenance, make sure your coverage is up to date! Call IIA at 1-855-478-3705 and explore our options for quality auto insurance today!