Alternator 101: Everything You Need to Know

From the headlights, the power seats, and the radio to the battery itself, the alternator in your vehicle is essential to powering everything you need to safely and comfortably navigate the road. So, what happens when this component fails? What does an alternator replacement at our service center entail?

As your automotive partner, our technicians can handle every alternator-related repair and service need. However, we also believe in giving our customers the knowledge and tools to recognize potential alternator issues. With these insights, you can proactively protect your vehicle and know the signs of alternator trouble long before you’re stranded on the side of the road.

So, what exactly is an alternator, and how does it work? What’s the difference between the alternator and the battery? Join us as we answer these questions and more, because class is officially in session!

The Alternator: What Is It? How Does It Work?

Your vehicle relies on three sources of electric power: the battery, alternator, and voltage regulator. The alternator is one of the most critical components because it acts as a generator by converting mechanical energy into electrical energy. Roughly the size of a coconut and typically mounted at the front of the engine, the alternator is small but mighty. It’s comprised of a rotor, stator, voltage regulator, diode rectifier, and cooling fan. But what do these parts do to help power your vehicle?

When you start the engine, the movement of the crankshaft drives the belt to power the alternator’s rotor. The rotor—which is surrounded by magnets—moves at an incredibly high speed within the stator, which is lined with copper wiring. This movement creates a magnetic field that generates high voltage (electric power) that the stator captures and sends to the voltage regulator to regulate and disperse to the components throughout your vehicle that rely on electrical power.

Behind the scenes, the diode rectifier converts the alternator’s voltage into energy the battery needs to recharge as you drive down the road. Why is this such a critical step? Your car battery relies on DC (direct current) electricity, but the alternator produces AC (alternating current); the diode rectifier converts the AC into DC, which the car battery can use.

Alternator vs Battery: What’s the Difference?

While the battery and alternator supply your vehicle with electrical energy, these components have two distinct purposes. The battery gives your vehicle the initial jolt of energy it needs to start the engine, similar to how a cup of coffee or an energy drink gives you an extra jolt of energy in the morning. When you start the engine, the battery wakes your vehicle, sending power to the starter, ignition coil, and other essential components.

The battery’s initial jolt is critical, which most of us know from dealing with a dead car battery that’s left us stranded. However, the battery isn’t powerful enough to handle all the electrical demands of your vehicle—and this is where your alternator takes over, powering the major electrical components and recharging the battery as you drive.

The alternator’s role in replenishing the battery’s power is critical to the relationship between these two components. For example, a failing alternator can cause the battery to die prematurely. The battery cannot carry all the demands of powering your vehicle’s electrical components, so a bad alternator can slowly drain the battery or lead to a string of dead batteries.

How Long Should an Alternator Last?

The lifespan of a car battery is a few years, but is the same true for the lifespan of the alternator? Fortunately, alternators are built to be nearly indestructible, given their pivotal role in powering your vehicle’s electrical components and their proximity to the engine. Because of this, alternators have much longer lifespans.

Depending on the conditions, you can expect an alternator to last anywhere from 60,000 to 100,000 miles or roughly seven years or more. There’s no set rule on how long an alternator can perform, with some instances of alternators failing prematurely due to worn components, excessive demands, and corrosion. Luckily, most drivers rarely have to replace the alternator, particularly with car owners trading their vehicles more frequently.

Symptoms: Is It a Bad Battery or a Bad Alternator?

With the battery and alternator responsible for powering your vehicle’s electrical components, it’s easy to mistake alternator trouble for a bad battery. Luckily, our team can diagnose the cause and repair the issue. But what are the symptoms that would determine the likely culprit?

Dashboard Light: Battery Alert

An alert on the dashboard is the most obvious sign of a problem with the alternator. The battery alert can signify issues with the battery, alternator, or another electrical component. Once you see this light, it’s time to bring your vehicle in for service and, in the meantime, look for other symptoms to determine the cause.

Dim Lighting & Slow Accessories

When you go to move the driver’s seat, is it slow to respond? Do you notice your headlights are brighter or dimmer than usual? These are indications that your alternator is struggling to keep up with the demands of your vehicle.

Stalling Engine & Multiple Dead Batteries

As a generator, the alternator is a critical source of power for your vehicle. When it starts to fail, you may experience more dead batteries than usual. A bad alternator can’t meet the demands of your vehicle or recharge the battery, forcing the battery to do most of the work and prematurely decline. Likewise, if your engine stalls frequently, this is a sign of a bad alternator since there’s not enough voltage to keep your engine and its components running.

Strange Smells and Sounds

Lastly, rely on your senses to alert you to alternator trouble. For example, you may hear growling or whining noises under the hood, which indicates the alternator is struggling to keep up with your demands. In other instances, you may notice a strange odor, like burning rubber or wires.

Proactive Steps: Can You Prolong the Life of the Alternator?

An alternator is designed to last 100,000 miles, but there are still a few steps you can take to proactively extend its longevity and overall operability. For starters, be mindful of who you trust to handle your vehicle’s repairs, especially when it comes to its electrical components. Our technicians use genuine OEM parts and high-quality electrical components, ensuring your alternator has the same caliber of parts used on the manufacturer’s production line.

You can also be more mindful of the alternator’s workload, especially when the engine is off. For example, your vehicle’s electrical system will power off a few minutes after you turn off the ignition. Still, many drivers reengage the system to listen to the radio, charge their phones, or enjoy the air conditioner or heater while they wait in the car. Powering off these electrical components when the engine is off can lighten the demands on your alternator and keep your battery from draining.

Powering the Road Ahead

Now that you know more about your car’s alternator, can you recognize the signs of failure? We certainly hope so because awareness is essential when behind the wheel. Knowing what to look for as you drive—from strange sounds and smells to slow-responding accessories—can save you the hassle of being stranded on the side of the road with a dead battery and a failed alternator.

Even then, you can rest easy knowing our team is always here to lend a hand and get you back on the road quickly and safely.