Your car’s alternator acts like an onboard power generator that converts mechanical engine power into electrical energy that the rest of your car can use. If your alternator starts to malfunction, it can cause lots of problems ranging from blinking and flashing lights to your car stalling out while you drive.

The cost to replace an alternator ranges from $100 to $1,000, depending on your car, where you live, and other factors. Most insurance coverage won’t cover the cost of an alternator replacement, with a few exceptions.^[1] 

Here’s what you need to know about alternators and what to do if they stop working.

What is an alternator?

An alternator is essentially a car-powered electrical generator for vehicles powered by fuel.^[2] Electric and hybrid vehicles don’t have an alternator.

Most people own vehicles powered by gasoline or diesel fuel. Yet, many features in your car rely on electricity — not liquid fuel — to power them, including your headlights, taillights, the vehicle’s on-board computer, heated seats, and even your windshield wipers.

When you drive your car, your internal combustion engine uses fuel to create mechanical power. That mechanical power goes to your wheels and helps spin a rotor inside of the alternator to generate power.

Hydroelectric dams work in a similar way: Falling water spins a rotor, which generates electrical power.

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Key elements of an alternator

When your car is running, the engine spins your serpentine belt, or drive belt, which spins your alternator pulley and a couple more elements in your engine compartment. That pulley, on the outside of the alternator, connects to a magnetic rotor inside the unit.

The rotor spins freely in place on ball bearings inside the alternator, surrounded by a series of coiled metal wires called the stator. The spinning action between the magnetic rotor and stator is what creates an alternating current (AC).

From there, the newly created electricity flows to a regulator, which controls how much electricity goes to the rest of your car to avoid frying it. Finally, the bridge rectifier converts the AC power into direct current (DC) power, which is what most electronics actually use.

Check Out: What is Mechanical Breakdown Insurance and Do You Need It?

Alternator types

As with any mechanical car part, a few different types of alternators exist. If your car uses diesel fuel, for example, you might have an alternator that offers more electrical output because diesel engines pack more punch than the same amount of fuel in a gasoline engine.^[3] Your car manufacturer will specify what type of alternator your car uses if you ask.

Can you drive with a faulty alternator?

Yes, it’s technically possible to drive with a faulty alternator, but you shouldn’t. Alternator replacement is one of those vehicle repairs that you need to tend to immediately. With a faulty alternator, your car can stall and shut off right as you’re driving down the road, which poses a huge safety hazard.

That’s an extreme case, but even if that doesn’t happen, a faulty alternator can cause all sorts of other troublesome electrical problems. If your defroster or windshield wipers don’t work to keep your field of vision clear in cold weather and rainstorms, for example, you might not be able to see the road.

Indicators of alternator failure

Luckily, plenty of warning signs usually indicate you have a faulty alternator before a worst-case scenario happens. Here are the most common signs your alternator might be failing:

• Dim or flickering headlights: Try revving your engine or turning different electrical features like the radio or climate control systems on and off. This challenges the alternator to produce more electricity and may cause your headlights to dim or flicker.

• Dead battery: If your car’s battery dies long before it’s time to replace it, your alternator may not be working correctly to recharge the battery as you drive.

• Unusual sounds: A bad alternator can cause whining, ringing, humming, or squealing sounds from your engine. This particular indicator can be hard to diagnose because the alternator and the engine have lots of moving parts.

• Stalling issues: Your engine powers the alternator, but the alternator also powers the very computer that runs the engine, including the fuel injection system and spark plugs. Without solid control over these, the engine stalls out.

• Burning smells: Alternators have a lot of moving parts that can cause friction and smells of burning when the alternator isn’t working right. If the electrical regulator isn’t working properly, power surges to the rest of the car may also cause burning smells.

• Other electrical issues: If your radio turns on and off every time your windshield wipers activate or your dashboard lights blink frequently — especially when you’re using a lot of your car’s electrical components — you may have a bad alternator.

Keep Reading: Are Extended Car Warranties Worth It?

Cost of alternator replacement

In general, you can spend anywhere from $100 to $1,000 to replace your alternator, but the cost likely falls between $350 and $900, according to J.D. Power. That’s quite a wide range, so here are a few factors that might influence an alternator’s replacement cost:

• Where you live: The cost of living in different parts of the country generally affects how much mechanics charge.

• What car you drive: Different cars require different sizes of alternators. And the configuration of  your car’s engine compartment can affect the amount of time it takes a mechanic to access your alternator, which increases labor costs.

• If your alternator fried anything else: A faulty alternator can fry other electrical equipment in your car if it sent out too much voltage, which requires additional repairs and a higher bill.

Does your auto insurer provide any coverage for an alternator?

Unless you filed a claim for a covered car accident that damaged your alternator, your car insurance generally won’t cover the cost to replace your alternator. Instead, it’s generally considered a normal and routine cost of car ownership.

One exception to this, however, is mechanical breakdown insurance. The lines between mechanical breakdown insurance and car warranties can be unclear. If you purchase this type of coverage, it’s important to know exactly what your policy covers and if you need to meet any requirements for keeping up with your car maintenance.^[4]

See More: Auto Body Repair Costs and Car Insurance Coverage

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How often should you replace your vehicle’s alternator?

Like any mechanical part, alternators do wear out over time. This usually happens every 150,000 miles or so.

The more electrical parts your car has, the more wear and tear your alternator can experience. Today’s cars have a lot more electrical components than older vehicles, so you have a shorter amount of time before you need to replace your alternator if it starts going bad. Again, this doesn’t apply to electric or hybrid vehicles because those vehicles don’t have an alternator.

Alternator cost FAQs