Home Diagnosis and TroubleshootingElectrical System and Electronics Alternator Replacement – Is It Really That Expensive?

Alternator Replacement – Is It Really That Expensive?

by Jordan Harris
Alternator Replacement

Are you facing troubles with starting your vehicle because the battery is not charging? Well, maybe you are facing some symptoms of a bad alternator and you probably want to learn what is alternator replacement and how much is the alternator replacement cost? If that is the case, then you are at the right place because there will be a lot to cover on this topic.

Having a problem like this can be a really frustrating thing to deal with. Namely, these alternators are extremely crucial when it comes to the proper work of every system in your car. Without them, we are basically left without power. This is why it is out of utmost cruciality for you to determine if the alternator is bad or not.

But how you can perform this task? Well, only by reading the symptoms. As you probably know, each component starts to develop a lot of symptoms when it is going bad. So, is the alternator. This is why you need to upgrade your knowledge and get a good grasp on the basics first and when knowing how everything works, you will be able to tell what is going on with your car. And we are going to help you out with that.

First, we will cover the basics of what is an alternator and what it does. Then we will cover how this component works and how it fails. After we will cover the symptoms of a bad alternator and then we will learn how to diagnose and sort out this issue and also the alternator replacement cost. Still, you need to know how much it will cost you to sort this out. So, if you want to learn more, follow along.

What Is An Alternator?

Now before we dive into the alternator replacement cost, let’s focus on some of the basics and learn what this component is. I bet that not a lot of people out there are familiarized with this component and want to learn more of the basic stuff concerning this component.

And we are going to cover everything when it comes to it. So, if you want to learn follow along, if you feel like you have that knowledge, you can jump to the replacement and the costs. Now let’s get into it.

So, what is an alternator? Does it alternate something? Well, not quite. More precisely, it generates electricity in the form of an alternating current. Also known as AC current.

This component basically is a generator for electricity. Similar to generators that produce power in hydroelectric plants. But in a smaller diameter.

They both take the mechanical energy and convert it into electricity. And as we all know, electricity is quite an essential thing.

These devices were firstly patented in the early years of the 20th century for generating power for mass consumption. But there was a long journey until they were introduced to cars.

The first automotive alternators were used in military equipment during WW2 because they prove that they are really good at what they do and that is creating power.

But it was up until the late 40s when cars started rolling from the production lines with alternators. The first cars in the world used a dynamo. But the invention of the alternator has brought a big change and offered a ton of advantages over dynamos. But how does the alternator work behind the curtain? Let’s explain next before we cover the alternator replacement cost.

How Does The Alternator Work?

Now before we cover the alternator replacement cost, let’s learn more about how this component works in practice. What is the method of action when it comes to this component creating electric current?

The alternator is a very compact device that is usually mounted on the side of the engine and the shaft is pointing to you when you open up the hood on a RWD car or it is pointing to the left side if you drive a FWD car.

This is the case because the shaft of this device is rotated with the help of the drive belt, which is also known as a serpentine belt or accessory belt.

This belt is rotated with the help of the crankshaft through the crankshaft pulley. And then this belt basically powers up all of the accessories in your car, like the alternator, power steering, water pump, etc.

The alternator has a pulley and this pulley is spun by the drive belt and then as the pulley spins, the alternator is creating electricity.

This power is AC but the diode of the alternator then converts it into DC because all cars use DC current. This is quite an essential task for the diode to convert these currents.

Inside this component, there is a shaft that is connected to an iron core that when spun produces power. We will not get into details. But what is important for you are the components that are inside of it.

These are the pulley, the front bracket, the rotor that is in the center and that spins to create current, the stator that is around the rotor, the rear bracket and the rectifier, and the brush holder at the rear of it. But why do these components fail? Let’s see up next.

What Makes The Alternator Fail, What Are The Causes?

Now before we covert the alternator replacement and the cost to do this replacement, let’s learn more about why the alternators fail. Knowing this stuff will be extra helpful in determining the reason why your alternator has given up on you. So, let’s dive into them.

The main reason why the alternator fails is because of the shaft that is inside of it. The bearings wear off after thousands of miles and this will cause the shaft to lose balance.

Once the balance of the shaft is lost, you will highly likely be able to have a properly working alternator. Whenever the alternator spins it will wobble and this will impair the alternator from producing power.

So, when you have a problem like this, maybe it is best to look for some rebuild options if the problem is mild.

Other components that fail are the rectifier, solenoids, as well as the brushes. Luckily, there are a ton of kits out there that will allow you to rebuild this component. But since you are looking for alternator replacement, you probably want to get this whole component replaced which is also a good idea since this component can cause you a lot of trouble if you don’t do so.

Now as we cleared the causes of why the alternator fails, let’s now focus on other things. Namely, the symptoms that this component produces are tell-tell signs that you got to replace it. Let’s cover them in detail next.

Symptoms Of A Bad Alternator For Replacement

The causes of why the alternator tends to fail are clear, now we can move to other things before we cover the alternator replacement cost. And that are the symptoms that will be present when this component fails.

Frankly, there are a ton of symptoms whenever a component fails. And same is for this component. You will start to feel them sooner or later. Luckily for you, we are going to cover them in depth in the following chapters. So, if you want to learn more, follow along.

1. Battery Light On The Dash

The first symptom that could indicate the need for alternator replacement is the battery light on the dashboard. But why this is the case?

Well, when this component doesn’t work well, it will leave your car battery constantly empty and the light for the battery will work non-stop.

Alternator Replacement

The charge this faulty alternator will deliver will be insufficient for the battery to be filled up to the max. Resulting in damage to the battery in the process.

Yes, that’s right, the battery could get damaged if you run your car like this for a long time. This type of work will be really detrimental to battery health in general. So, whenever you replace the alternator, you will also have to replace the battery as well in most cases. Now let’s move to the next symptom.

2. Car Doesn’t Want To Start

The second very common symptom of a bad alternator is the situation when the car doesn’t want to start. It will keep cranking because of the low voltage of the battery or will not produce any noise. Only a clicking sound from the starter.

In these situations, it is rather difficult to determine whether this is a starter, solenoid, relay, battery, or alternator problem.

This is why you need to investigate the matter further. You need to bench test basically all of the components to be sure what could be causing the issue.

And one of them is that the battery doesn’t get the charge needed to run and eventually it gave up and you are not able to start the car. This is why you need to become a good troubleshooter and know the method of action of each of these components to determine what is wrong.

3. Grinding Or Squealing Noises From The Engine Bay

The third symptom that indicates a need for alternator replacement is the situation when there are noises produced by this component.

As we said, the inner bearing can fail and the shaft that is spinning will lose balance. Whenever there is a loss of balance there will be symptoms like this one.

These noises can be squealing at first because the belt will wobble around. But soon after they could turn into more pronounced noises. The rotor will start to grind against the stator and this will create these unbearable noises.

Whenever you have grinding noises, the best would be to replace the whole unit and not rebuild it. Doing this will guarantee that there are no problems in the near future with this component. Now let’s move to the other symptoms.

4. Dome Lights Start To Flicker

The next symptom that could indicate a need for an alternator replacement is the situation when the dome lights are flickering.

These dome lights are usually on whenever you open the door. But if they start to flicker like in a horror movie when you open the door, then it means that there is an issue with the power generator which is the alternator.

This component will not produce enough electric current to keep these lights on and they will constantly flicker and cause you trouble.

What is important for you is to note this issue and sort it out quickly. The faster you solve it, the less the chance for you to end up with a car that is unable to start because of a bad power-generating component.

5. Radio And Other Accessories Bug Down Frequently

The last symptom that could indicate a need for alternator replacement is the situation with the accessories inside of the cabin that are starting to show bugs.

I mean not real bugs, but bugs in their operation. They turn on and off all the time, they flicker. You lose the cluster lights or the car shuts down completely.

All these things indicate a problem with the power in your car. So, whenever you notice something like this, it is really important to see the condition of the battery first and then check the condition of the alternator.

You need to learn how to diagnose this component. And in the following chapter, we are going to cover precisely that and help you overcome your problem.

How To Diagnose A Bad Alternator?

So, how you can tell if you need to perform an alternator replacement? Well, it is a relatively easy thing to do. You will need a multimeter for this work just to know since you will be working with electricity. But there are also other symptoms that are a tell-tell sign that there is a problem with this component even without bench testing it. We will go through them first and then we will learn how to bench test them.

The first symptoms of a bad alternator are the things we have covered, the loss of power in the cabin, and the components losing power frequently.

In addition to this, there will be noises from the belt or the component itself. It will love to grind and cause issues.

You can also observe the pulley and see if it wobbles around. If it does, it means that the bearing inside is done and needs to be replaced or the whole component replaced on the vehicle if you want to charge the battery as it should.

But if you want you can take things even further and bench test the component. For this, you will need a multimeter tool. You can grab these on Amazon very cheaply or at your local parts store.

Then you will need to test if the alternator is charging the battery. You will need to attach the positive probe to the positive terminal and the negative to the negative terminal and adjust the multimeter to measure volts. Then start the car and leave it running like that. Observe the values that you get. And if you get values in the range of 14.2 and 14.7 volts it means that you are good. If not, the alternator is not charging well.

Alternator Replacement

Now let’s assume that you performed diagnostics of your alternator and you deemed the alternator bad. So, this component has to be replaced right? Let’s see how this is done.

Replacing the alternator is a really easy job that anyone can do it. The important factor when it comes to this work is the position of this component. Some manufacturers tuck these components away and is a pain to get them.

So, you need to locate it first and make a plan for attack. You need to get this job done in a weekend at most. Watch a ton of YouTube videos of how this is done and get focused on the job.

Purchase a new component from the shop that is specific to your engine. Get some basic tools like a socket wrench and start working.

The first thing you will need to do is to remove the battery cable and make sure that there is no power. Then loosen up the drive belt. And you can do this by adjusting the tensioner. Just unbolt the bolt and the tension will disappear.

Then remove the electrical connection as well as the bolts that are holding the alternator to the bracket. Then the component should come off.

Installing the component is the same thing in reverse order. Then you will be good to go.

Alternator Replacement Cost

So what does the alternator replacement cost? Well, it is not cheap. A good quality alternator is somewhere between $300 and $600. It is expensive.

Alternator Replacement

The labor is also expensive and could cost you a few hundred dollars if you do this at a shop. So, the total could end up to $900 in the worst cases. But if you do this at home, you will only pay for the component.

How To Rebuild An Alternator?

Now let’s see how you can rebuild an alternator. What you will need to rebuild one of these components?

The short answer is that you will need to get a rebuild kit that is specific to your application. The kits really depend much on the extent you want to take this rebuild to. Whether you want to replace the bearings, the diode, and other components on it. And in the following chapters, we are going to explain these processes.

Alternator Bearing Replacement

In order to perform an alternator bearing replacement, you will need to remove the component from the vehicle and place it on a bench.

Then disassemble the component into bits. The bearing is located on the shaft of the rotor. You will have to remove the old one and install the new one. Then assemble everything well and you will be good to go.

Alternator Diode Replacement

But what about alternator diode replacement? For this work, you will need a kit that includes the diode.

This diode is mounted on the rear of the component and it is really easy to remove it. There are only a few bolts that are holding it.

Remove the bolts and it will pop off. Then bolt the new diode in and mount the component back in its place and connect the wires. A very simple job.

Alternator Belt Replacement

Now let’s see what we can do about the alternator belt replacement. It is often advised for you to replace this component as well when you do the alternator. Since you are already there and replacing it will be really easy.

Before you do anything, take a lot of pictures. Make sure that you know the layout so you don’t have trouble routing the belt.

You will also be needing a new tensioner for this job. Start the replacement process by loosening up the tensioner and then just removing the belt.

After you remove the belt, install the new tensioner and route the new belt. Lastly, tighten up the tensioner and you will be good to go.

Alternator Belt Replacement Cost

The alternator belt replacement cost is fairly low. If you do this job at a shop, you will highly likely end up paying more than $350.

Alternator Replacement

Or if you decide to do this work at home, you will end up paying only for the belt and the tensioner. And this cost is about $100 more or less.

Cost Of Alternator And Battery Replacement

So, what is the cost of an alternator and battery replacement? The cost of battery and alternator replacement is more than $500 for the parts alone.

If you decide to replace the parts as well as to do this at a shop, you will end up somewhere shy of $1,000.

Alternators: How Long They Last, Signs of Failure, & Replacement Costs

  1. The alternator is responsible for supplying power to all of a vehicle’s electrical components and recharging the car battery at the same time.
  2. Alternators typically last between 40,000 to 100,000 miles and are affected by factors such as driving habits and climate.
  3. Warning signs of a bad alternator include unusual engine noises, difficulty starting the car, dimmed headlights, illuminated dashboard warning lights, and malfunctioning electrical systems.
  4. The average cost for alternator replacement is between $350-$400, with labor costs averaging around $120-$200.
  5. Aftermarket alternators can save money, but buyers should beware of lower-quality parts and opt for a new OEM alternator if possible.
  6. Replacing the serpentine belt, wiring harness plug, and the battery may also be necessary during alternator replacement.
  7. Minor repairs, such as replacing the belt or cleaning electrical connections, may be an option instead of full alternator replacement.
  8. Used alternators are not recommended due to the risk and lack of warranty, while remanufactured alternators are a better option than rebuilt ones.
  9. The total cost of alternator replacement can vary based on geographic location, vehicle make and model, and other factors.
  10. Understanding the importance and function of the alternator, as well as the potential costs of replacement, can help vehicle owners prepare for necessary repairs.


In this article, we covered a lot about when it comes to alternators and their work. We learned how they function and what is the method of action.

Then we have covered the causes of why they fail as well as the symptoms they produce. Then we learned how you can replace on and the cost you will have to pay to do so.


Now let’s answer some frequently asked questions.

What Is An Alternator?

An alternator is a device that serves the purpose of generating electric power in your car. It powers up the accessories as well as charges up the car battery.

How Much Does An Alternator Replacement Cost

The average alternator replacement cost is about $600. About $300 for the part alone and about $300 for the labor. There are cheaper deals. Namely, rebuilding the alternator and replacing the faulty components.

How Much Is A Alternator Replacement

The average cost to replace an alternator is about $300 for the part alone. Some though can be even more expensive. The labor is about $300. But if you replace it by yourself it will be really cheap.

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