Symptoms of a Bad Alternator | Autance

While every part of your automobile has its role in making your vehicle work normally, some of them have bigger…

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Symptoms of a Bad Alternator | Autance © Symptoms of a Bad Alternator | Autance

While every part of your automobile has its role in making your vehicle work normally, some of them have bigger roles. The alternator is one such component because it is critical in the electrical power system of your car. When the alternator is not working well, it can lead to bigger problems. This is why diagnosing any issue with your alternator should be done as quickly as possible.

What Is An Alternator?

If you are not an expert in cars, then you might wonder exactly what an alternator do? Well, the alternator is the electricity supply of your vehicle, which actually requires quite a lot of electricity to start the engine. The other parts of the car will also need some of this power, which cannot be supplied by the battery due to its limited supply.

On the other hand, an alternator has the capability to charge the battery while the engine is running. It does so by converting mechanical energy from the spinning pulley into electrical current. Because it has to work hard, it is natural that the brushes, the rotor, and its other parts get worn out over time. Thus, they will need replacing at some point. The symptoms listed below are signs of a bad alternator and that it should be checked out by an expert.

What Causes A Bad Alternator?

There are a few reasons why your alternator is not working properly.

  • The most common reason is a loose belt.
  • Another reason is when the diodes go bad, meaning it cannot transmit the voltage needed by the car.
  • The bearings, which is where the alternator rotates, can also wear down and prevent the alternator from functioning properly.
  • A problem in the field voltage that the alternator receives will also lead to bad alternator symptoms.

Symptoms Of A Faulty Alternator

  • Flickering Headlights

One of the earliest signs of a struggling alternator is when the headlights seem dimmer than normal, or when it starts to flicker. You will notice this when you are either accelerating or decelerating. If your alternator is in optimal shape, then the headlights stay bright despite the speed you are driving at.

Another sign is when the lights look dim across the dashboard, so you might need to have an alternator test to have them checked and repaired.

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  • Weak Or Dead Battery

When your battery seems weak or is dead, it is a sign that your alternator is failing as well. While it can charge up your car’s battery, it cannot keep it from dying. However, you will need to know what the difference is between a bad alternator and a weak battery.

There are some ways to check this out. First, you can check the battery gauge (without starting the car) on your dashboard. If it continues to have a strong charge, then it means your battery is still good. However, once your alternator malfunctions, other electrical devices will try to get power from the battery, meaning it could die faster than normal.

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  • Strange Sounds

The alternator has quite a few moving parts, which should spin when it is working properly. However, when one part breaks off or starts to work ineffectively, it makes some unusual sounds. Specifically, if you hear a grinding sound, it can be a sign that you have a bad alternator. It means the bearing is worn-out and creates this grinding sound.

Your vehicle may also create a whining sound when the voltage regulator is unnecessarily sending signals to the alternator to continue charging. Thus, any of these two different sounds may be a sign of a problem with the alternator.

  • Problems Starting The Car

One of the reasons why your car takes longer to start or turns over a few times before starting is that your alternator is bad. It may also be because of a dying or weak battery, so you will need to rule this out to conclude that the alternator is no longer working.

Many cars have a warning light that will go up when there is a problem with the alternator. It either looks like a battery or has the letters ALT. When it is not working properly (meaning an output of 13 to 15 volts), the warning light goes on. When the alternator is not yet fully dysfunctional, the light may sporadically come on and off.

  • Electrical Failures

Your alternator is your vehicle’s main source of electrical power, so electrical problems can be traced directly to a bad alternator. These failures can be observed in a few ways, like the power windows operating slower than normal. You may also notice the power locks, seat heating, and windshield wipers are affected.

These can be warning signs of a dysfunctional alternator but you should make sure it is the root cause by getting your car tested. Some people who are familiar with cars will know which home tests can be done, but the best thing to do is to get it to a garage. A trained mechanic will know exactly what the problems are and how they can be fixed.

Checking What Is Wrong With Your Car

One of the biggest issues is whether it is a problem with the alternator or the battery because they work hand-in-hand. If you want to find out on your own, you can try these out.

  • Leave the engine running and remove the negative cable of the car’s battery. When the vehicle stalls, then it means the problem is the alternator. If not, then you have a battery issue.
  • Ask someone to check the headlights and start your automobile. Keep the car in park mode and step on the accelerator. If the headlights look dimmer or switch off altogether, then it means your alternator is not working properly. Otherwise, your alternator is functioning well.

A bad alternator can be ignored in the beginning but once these symptoms show up, you need to have it fixed as quickly as possible. Only then can you be sure that your automobile has the energy it needs to run properly.


  1. Symptoms of A Damaged Or Failing Alternator – Buy Auto Parts
  2. How to Check an Alternator – Wiki How
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