As a vehicle owner, you’ve probably heard of the “alternator” before. However, besides recognizing that it’s a crucial part of your car, you might not know what it actually does.

In the simplest terms, your alternator is an electrical generator mounted on your car’s engine to convert kinetic energy into electrical energy. While your vehicle is running, the alternator powers the car’s electrical systems and keeps the battery charged.

If you’re experiencing alternator problems, you may find that your car struggles to start or only stays on for just a short period. But before it gets to this point, there are some key signs that your alternator might be failing.

Here, we’ll cover everything you need to know, including the top things to watch out for and why an extended warranty (more accurately called an auto protection plan or vehicle service contract) is the best way to protect yourself from the cost of unexpected component failure.

Top Warning Signs of a Failing Car Alternator

An alternator is considered a “wear and tear” component of your vehicle, which means it’ll need to be replaced with use. More specifically, it’s the rotor and brushes within that can wear down as you drive or as they’re exposed to the elements. This isn’t to say that alternators can’t last a long time — they absolutely can — but if your vehicle is a little older, chances are you’ll need to replace your alternator in the near future.

When an alternator is beginning to reach the end of its lifecycle, you may experience some issues that signal it’s on the brink of failure. Let’s take a look at some of the most common symptoms of a bad alternator so you can get to a mechanic before things break down completely:

1. Dimming or Flickering Lights

Your alternator is the power supply for your vehicle’s electrical systems and battery, so when it starts to become less efficient, it makes sense that it’d affect the things it powers. One thing you might notice early on is erratic light behavior, such as extremely bright or dimming headlights and dashboard or battery lights, or your speedometer/tachometer may completely stop working. Lights may also flicker, going from bright to dull to bright again. This flickering could be rhythmic or seemingly random.

If you want to pinpoint whether this is definitely something to do with your alternator, a bad battery, or just another electrical issue, make sure to look for a pattern. Do the lights flicker when you do something else that draws electricity, like turning on the radio or adjusting the A/C? If the answer is yes, you can be almost certain your alternator is the problem.

2. Dead Battery

Batteries in gas-powered cars aren’t designed to power the vehicle themselves. They’re just supposed to deliver the juice needed to help the starter motor kick the rest of the engine into motion. So, if your alternator is struggling, your battery’s health will be affected.

Of course, a dead battery may just be a problem with the battery itself, but there’s a real possibility that your alternator is the root cause. When an alternator begins to fail, the car’s battery is forced to make up for it, but the charge it uses to get your vehicle running isn’t sufficiently replaced. This will run down completely eventually, resulting in a dead battery and a car that no longer comes to life no matter how many times you turn the key.

3. Electrical Malfunctions

An alternator that doesn’t efficiently produce power will affect other electrical systems in your vehicle, too. Especially in modern cars that are packed full of cutting-edge technology, as energy becomes less available, malfunctions are bound to happen. Noticing one electrical quirk could just be an isolated issue, like a worn-out motor or corroded wires. But if you experience several electrical problems at once, something bigger is almost certainly at play.

Your alternator is one of the most likely sources of electrical issues, and you may not even realize you’re experiencing lower power levels until you put more demand on your car’s systems — like turning on an interior light or using your power windows.

4. Unusual Noises

While other signs of a failing alternator might be less obvious until they become severe, strange noises coming from under your hood are a little harder to miss. Some drivers will complain of a growling/whining noise when they switch on their engine, which can be a clue that your alternator is struggling.

Alternators are driven by an accessory belt or serpentine belt that works together with a crankshaft pulley. The pulley spins on a shaft supported by bearings or bushings. If anything causes the pulley to no longer be in alignment with the belt correctly, if it is canted on the shaft, or if the bearings or bushings are worn out, some sort of noise will let you know.

5. Warning Indicator Light

Every driver hates the sight of a dreaded dashboard light, but they’re great for helping you tackle a problem before it gets out of hand. Most cars built in the last decade will have a warning light dedicated to alternator issues, usually shaped like a battery, or sometimes they might say “ALT” (alternator) or “GEN” (generator) instead.

That’s right. The little battery warning light isn’t for the battery itself but the alternator attached to it. Most alternators have an output of 13 and 14.5 volts that try to maintain a constant level. Computer systems in your car will monitor your alternator’s output, and if it drops below a preset limit, the light will trigger.

6. Stalling or Difficulty Starting

Any number of mechanical issues can cause stalling or hard starts, but your alternator may be the culprit, too. If a faulty alternator isn’t recharging a car battery properly, the battery won’t have enough power to start your engine as it should. Trouble starting or stalling after the car has started up could be a sign that the spark plugs aren’t getting enough energy from the alternator to keep the engine running.

7. Burning Smell

An overworked alternator may begin to smell like an electrical fire or even burning rubber. As wires and belts start to overheat, your nose will probably pick it up. These smells are distinctly different from the smoky smell of burning oil, for example, or the sweeter scent of overflowing coolant. Just because you can’t smell anything doesn’t mean all is well. However, while odors can help you narrow down what might be wrong with your vehicle, the alternator can still fail without them.

Extended Warranties: Protecting Against Alternator Failure

No matter how well you maintain your vehicle, it’s an unfortunate reality that all auto parts fail eventually. When they do, you can bet your bottom dollar it’ll happen at the worst possible moment, leaving you stranded hundreds of miles from home and faced with an auto repair bill you couldn’t possibly afford. To protect yourself against the cost of unexpected alternator failure, it’s highly recommended that you invest in an extended auto warranty. And Endurance is America’s most trusted provider.

Since 2006, we’ve helped thousands of drivers save some serious money on the rising cost of car ownership. We offer a wide range of auto protection plans aimed to cater to almost anyone, from casual commuters to rideshare drivers to high-mileage car owners and even select luxury vehicles. And if our base plans don’t quite meet your individual needs and budget, we can customize one that works for you.

On top of market-leading coverage, we also throw in some of the best benefits around. All Endurance plans come with 24/7 roadside assistance (including towing, fuel delivery, and lockout services), rental car reimbursement, and trip interruption costs as standard. If that wasn’t enough, every Endurance customer can also choose to activate an amazing Elite Benefits package, adding on up to four tire repairs or replacements annually, key fob replacement, up to $500 in collision discounts, and up to $1,000 in total loss protection.*

We’re also the direct administrator of all our plans, so there are no pesky middlemen to deal with when you come to make a claim. Our award-winning customer service team is available to answer queries via phone or email or download the Endurance app to put all of the most important information right in the palm of your hand. Better yet, all Endurance plans are fully transferable to subsequent owners — giving you extra selling power and potentially increasing the value of your vehicle should you decide to part ways with it.

Alternator FAQs

Do you still have some questions about alternators and signs of alternator failure? You might find the answers right here:

How do I know if my alternator is on its way out?

There are a number of ways you can tell that your alternator is beginning to fail. Strange smells, noises, and dashboard warning lights or check engine lights are often the first signs, as are electrical component malfunctions in your vehicle. Eventually, your battery will be so depleted that your car will begin to stall when driving or won’t start up at all.

Will a bad alternator drain a battery when the car is off?

A bad alternator rarely drains a battery when the car is off, but it’s certainly possible. This is usually due to a faulty component within the alternator itself or connections to it. For example, a failed diode in the alternator will create a closed circuit that drains your battery even when the engine is switched off.

Can AutoZone test an alternator?

If you have concerns about your alternator’s efficiency, AutoZone offers fast, free testing. Just head to your local AutoZone location and ask about their part testing and diagnostic services.

Do alternators fail suddenly?

Unfortunately, alternators generally fail suddenly without much warning. If you’re lucky enough to spot any of the signs before the worst happens, head to a mechanic immediately, as your car won’t run for long without a healthy alternator. Keep an eye out for electrical malfunctions, strange smells/noises, and related dashboard lights.

Drive With Total Confidence

AAA statistics estimate that the annual cost of car ownership has reached over $12,000. So, it’s safe to say that driving any vehicle, new or used, is becoming increasingly expensive. The only way to drive with total confidence is with an auto protection plan watching out for you and any unexpected breakdowns.

Call an Endurance plan advisor at (800) 253-8203 or request a FREE quote. If you’re still interested in shopping around, see your price now to compare against other providers!

Visit our extended warranty blog for more helpful articles from auto experts, including provider comparisons against CarShield and CARCHEX, vehicle ownership tips, and more.