Signs Of A Bad Alternator

Does your car have symptoms of a bad alternator? You need to fix it right away. Here's the ultimate guide to help you troubleshoot if you have a bad alternator.

The alternator of your car is what makes all its electrical accessories work and keeps your battery alive and functional.

There are many signs of a bad alternator, from being unable to start the car to burning smells and whining noises.

Whatever symptom you notice, we will cover it and help you determine if the alternator is the cause of your automotive troubles.

The alternator is a relatively simple part of the car, but it is vital for almost every process that requires electricity.

Let’s get started right away!

Related:What Does An Alternator Do?How To Test An AlternatorAlternator Repair And Cost

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Bad Alternator Symptoms

alternator repair cost

As the alternator is responsible for charging the battery and powering the electronic accessories in the car, many electrical issues can arise if an alternator is bad.

The most common signs and symptoms of a bad alternator are the following:

  • Dead battery
  • Flickering lights
  • Burning smell
  • Whining noises
  • Warning light

In the following sections, we will cover each of these signs and symptoms so you can determine whether the problem lies in the alternator or if the culprit is elsewhere.

Dead Battery

mechanic changing car battery

As mentioned previously, perhaps the most important task of the alternator is to charge the battery.

As a result, a bad alternator will not charge the car sufficiently, which will soon result in a dead battery.

Whenever your car has a dead battery, it is important to determine whether or not the alternator is the culprit. A bad alternator will empty a new battery very quickly.

A good way to test if the battery or alternator is responsible is to jumpstart the car.

The battery is the likeliest culprit if the car keeps running after the jumpstart. A car with a bad alternator will usually shut down shortly after.

There is also a relatively simple way to test an alternator.

Flickering Lights

car headlights

It is no secret that your car’s lights need constant electricity to work properly.

A bad alternator will produce little electricity or do so inconsistently, making the lights flicker.

This can apply to any type of light but is usually easiest to notice in the headlights.

The light will not necessarily flicker. Some might be brighter than usual, while others will be dimmer. This is all due to the inconsistent voltage produced by the alternator.

Burning Smell

man and bad smell inside car

A more serious symptom that you might notice is a burning smell of rubber or electric wires.

The burning smell can be caused by various reasons, including a faulty serpentine belt, overheating alternator, or even an electrical fire.

These symptoms can have serious consequences. Therefore, the best thing to do is stop the car and investigate where the smell is coming from.

Bad smells are not exclusive to bad alternators, but, whatever the cause might be, it should be investigated as soon as possible.

Possible culprits of bad smells include the air conditioner, brake pads, coolant, exhaust leaks, and much more.

Whining Noises

noise while driving

A bad alternator may produce a variety of noises, including high-pitched sounds or knocking, depending on the specific problem.

In most cases, a bad alternator will produce a whining noise unless the bearings are deteriorating, which will create a knocking sound.

Much like the smell, noises are not exclusive to alternators.

This is why you should always consider other symptoms that may show up alongside these signs to have a more accurate sense of where the problem lies.

Warning Light

battery warning light

In most cars, a warning light will indicate if there is something wrong with the alternator or battery.

An alternator in poor condition could make the dashboard blink or flicker for the same reasons that headlights do.

If you are on the road and this light illuminates, you should turn off all the non-essential electronics to get a few more miles and stop at a safe location to address the problem.  


Car Alternator
A car alternator – Converting mechanical energy to electrical energy inside a car

An alternator that does not work properly will definitely reveal itself in one way or another.

In most cases, there will be a few signs, such as flickering lights, that are almost exclusive to alternators. However, there are also more general signs and symptoms.

For example, a drained battery could be due to a faulty battery or a faulty alternator. It is important to eliminate one of those possibilities before replacing a battery.

Other bad alternator symptoms include whining noises, a burning smell, or a warning light illuminating on the dashboard.

Whatever the symptoms and signs that appear, you should check and resolve the problem as soon as possible, especially if you notice a burning smell.

Always consider all the symptoms and signs to see the bigger picture, as many of them will overlap with other problems.

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Bajro Muric

Bajro is an ASE-certified master technician and car enthusiast with a love for writing and teaching. He writes about anything regarding cars, from common problems and fixes to racing.