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 the electrical accessories work and keeps your battery well and alive.

Consequently, a bad alternator will show many signs – from being unable to start the car to burning smells and whining noises.

Whatever the symptom may be, 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 its function is vital for almost every type of process that depends on electricity.

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 may be present 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

Down below, we will cover each of these signs and symptoms so you can differentiate if the problem lies in the alternator, or the culprit may lie somewhere else.

Dead Battery

mechanic changing car battery

As mentioned previously, one of the most important tasks of the alternator is to charge the battery.

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

Whenever you have a dead battery, it is important to rule out if the alternator is the culprit or not. A bad alternator will empty a new battery in a short period.

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

If the car keeps running after the jumpstart, the battery is the more probable culprit. A car with a bad alternator will in most cases shut down shortly after.

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

Flickering Lights

car headlights

It is no secret that light needs constant electricity for them to work properly.

A bad alternator will produce little electricity or do so inconstantly which may show as the lights flicker.

This may apply to any type of light but is usually best observed in the headlights.

The light does not necessarily have to flicker, some may be brighter than usual, while another will be more dim than usual. This is all due to an inconsistent voltage produced by the alternator.

Burning Smell

man and bad smell inside car

A symptom that may be perceived as more serious is a burning smell of rubber or electric wires.

The burning smell can be due to a myriad of reasons, including a faulty serpentine belt, overheating alternator, or even an electrical fire.

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

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

Possible culprits of bad smells include the air condition, 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, but also knocking noises depending on the specific problem.

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

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

Therefore, you should always consider other symptoms that may show up together with these symptoms to have a more accurate problem where the problem lies.

Warning Light

battery warning light

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

An alternator in a very bad condition may make the dashboard blink or flicker for the same reasons headlights do.

If you are on the road and this light illuminates, you may turn off all the non-essential electronics to get a few more miles and stop at a safe location and 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 most definitely show in one way or another.

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

For example, a drained battery may either be due to a faulty battery or a faulty alternator. Therefore, it is important to exclude either one of those before replacing a battery.

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

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

Always take into consideration all the symptoms and signs to get the bigger picture as many signs and symptoms overlap with other problems.

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Bajro Muric

Bajro is a big car enthusiast with a love for writing and teaching. He writes about anything regarding cars - from common problems and fixes to racing.