Bad Alternator VS Bad Battery

Bad Alternator VS Bad Battery – Where To Start Diagnosing?

Are you experiencing no start issues with your car and you are thinking about a bad alternator vs bad battery? What could fail and cause this problem to you? 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 no-start issue with your car can be a really frustrating thing because you will basically be lacking the ability to start your car. You will not be able to run the engine and could be left out stranded in the middle of nowhere with no help around.

This is why having these two components always in check should be your top priority if you want to avoid something like this happening to you and drive safe on the road. And for this, you need to learn how to think critically and understand what these two components do in reality and how they fail and what could cause when they fail. So, this is your top priority for now. That’s why we are going to help you out.

First, we will learn what is a car battery and what is an alternator. Then we will cover the bad battery symptoms and bad alternator symptoms. Then we will compare the signs of bad alternator vs bad battery and then we will learn how to diagnose and fix this problem and we will cover the costs involved in this work. So, if you want to learn more, follow along.

What Is A Car Battery? – Bad Alternator VS Bad Battery

Now before we dive into more complex topics such as bad alternator vs bad battery. Let’s first cover some of the basics and learn what is a car battery in general. First, we are going to cover the battery and then we will discuss the alternator. This will be extra useful for beginners who do not understand how these two components work. Now let’s begin discussing.

A car battery in simple words is a component that stores electricity to allow you to start your vehicle. Not to confuse this car battery with the batteries on hybrid or electric cars. Those are lithium-ion batteries and are a completely different thing.

The car battery on the other hand is a lead-acid design. This means that this battery is working with the help of lead and acid. But how do they work behind the curtain?

Well, in each battery there are about six cells on average. In each cell, there are lead plates that are submerged in sulfuric acid. The average lead-acid battery is able to store 12V of power. About 2V per cell. Enough to allow you to start your car.

This type of battery was invented back in 1859 by Gaston Plante, a French physicist. And even after more than 100 years, it hasn’t changed a lot. It is still an irreplaceable component in each internal combustion engine. Why I’m telling you this?

Well, because this type of battery is able to supply high surging currents. Only a really strong current can spin the starter and start the engine. This is why this design is still widely used and is the battery of choice. Now before we cover bad alternator vs bad battery. Let’s learn more about alternators.

What Is An Alternator?

Now as we cleared the basics of car batteries and we understood how they work and their goal. Let’s now focus more on the alternator before we cover bad alternator vs bad battery. Knowing how the alternator works is another important thing for you if you want to determine if you are dealing with a bad alternator or a bad battery.

The important thing when it comes to alternators is to understand their method of action. Alternators are generators of electrical current.

They generate AC current which is converted into DC. Then this electric current is used to top off the car battery and also power up the engine.

You need a stable alternator if you want to have a good battery and a good working engine. If the alternator is bad, the engine will struggle to run because there will be no more constant electrical current to the spark plugs.

If the spark plugs don’t work, then there will be no ignition of the fuel inside of the cylinders. So, the engine will simply stop working and you will not be able to drive your car.

Another thing that is worth noting is how this alternator works. This component basically is a generator as we mentioned. This component generates power with the help of the serpentine belt that is spun by the crankshaft and then this belt powers all the accessories in your car like the alternator, AC, power steering, etc.

So, this serpentine belt helps rotate the shaft of the alternator, and then inside of the alternator magic happens and creates electricity. But you are still confused probably when it comes to bad alternator vs bad battery. This is why we need to learn the difference and compare the two.

Bad Alternator VS Bad Battery

Now as we covered the basics and learned more about both the car battery and alternator and what is their role. Let’s now focus more on a bad alternator vs bad battery. Let’s compare these two components and help you understand better their use.

Well, the main difference between the two components is that one of them helps to start the car which is the car battery. While the second component helps keep the battery charged and also supplies the engine with electrical current in order to run well.

Bad Alternator VS Bad Battery

Let’s say that if you have a bad alternator, you might be able to start the car. But this alternator will not be able to charge up the battery and deliver the necessary power to it. So, you will face bad alternator symptoms and the car will shut off since the battery will be drained really fast since the alternator is not producing power to charge this battery.

On the other hand, if you have a completely dead battery you will be able to jump the car and drive off because your alternator is working. So, even if the battery is dead, the alternator is still producing power and until the alternator is working, the car will run well until you turn off the engine. Simple as that. Now as we cleared off a bad alternator vs bad battery. Let’s focus more on the bad battery symptoms.

Bad Battery Symptoms (Compared To An Alternator)

Now let’s cover the bad battery symptoms. This will help you quite a bit when it comes to a bad alternator vs bad battery because when you know the symptoms, it will be really easy for you to diagnose a problem whether it is the battery or the alternator. Now let’s begin covering the symptoms

1. Battery Light

Now let’s cover the first of our bad battery symptoms which is the battery light. Whenever you have a bad battery, you will experience this battery light on the cluster.

Bad Alternator VS Bad Battery

This is a clear indication that you have a problem with either the battery or the alternator. It could be triggered in both cases of a bad alternator vs bad battery. Mainly because if you have a bad alternator, you will not be able to get a proper charge of the battery. So, you get where we are going. This symptom can be a bit misleading. Now let’s cover the rest.

2. Car Won’t Start

The second in our list of bad battery symptoms that we would like to cover when it comes to bad alternator vs bad battery is when the car doesn’t want to start.

When you have a problem with a completely dead battery, the car won’t start will be the case. The only thing that you will hear will be a click-click sound that will be produced and that’s it. This is a clear indication that your battery is empty or possibly there is a starter or a starter solenoid issue. But in most cases, when this happens there is no problem with the alternator.

3. Car Struggles To Start But Runs Fine

The second bad battery symptom that we are going to cover is when the car struggles to start but runs fine. When it comes to a bad alternator vs bad battery, it is worth mentioning that this situation is mostly caused by a bad battery.

More precisely a weak battery. If one cell of the battery is dead, you will highly likely end up with a low charge. So, this low charge will mean that you will not have enough power to crank and start the engine from the first try.

The car might struggle to start at first but after it starts it will not have trouble running and the car should drive fine. So, when you have a situation like this, the best bet would be to check the battery and see if it’s any good. Now let’s move on to the next symptom of a bad battery and then we will learn how to diagnose a bad alternator vs bad battery.

4. Car Won’t Start In Cold

The last in our list of bad battery symptoms that we are going to cover is the situation when the car won’t start in cold.

This is a situation that is often caused by a weak or bad battery. What happens is that in winter, temperatures are getting really low and this affects the battery to deliver electrical current.

So, in these situations, you will notice how the car won’t start in cold. When this happens, the battery is probably near failure. So, it might be best to replace it with a new one. But first, you will need to diagnose it. But more on that later on when we will cover bad alternator vs bad battery. Now let’s cover the bad alternator symptoms.

Bad Alternator Symptoms (Compared To A Battery)

Now as we covered the bad battery symptoms before we learn how to diagnose bad alternator vs bad battery, let’s cover the bad alternator symptoms as well. Knowing these symptoms will help you diagnose the problem and determine if you have a bad battery or a bad alternator.

What is worth noting is that you can also expect to have the battery light when you are experiencing issues with the alternator as well. So, we are not going to include it in this list in order not to repeat ourselves. Now let’s begin with the symptoms.

1. Whining Or Grinding Noises In The Engine Bay

The first in our list of bad alternator symptoms is the symptom when you experience grinding or whining noises from the engine bay. At first glance, you will think that it’s just a pulley.

But this isn’t always the case. If you dive deeper you will notice how the shaft of the alternator has play in it and doesn’t rotate the right way. It will soon start grinding and there will be internal damage to the alternator.

All this is often caused by a bad bearing inside of the alternator. So, when it comes to bad alternator vs bad battery. This symptom is often connected with a bad alternator. Now let’s move on to the next symptom.

2. Lights Flicker Inside Of The Car

The second in our list of bad alternator symptoms is the situation when you have flickering lights inside of the car.

When the alternator is not producing enough power which is about 15V, the accessories inside of the car will malfunction and cause you a ton of trouble.

So, if you notice how when the car starts there is some dimming in the lights or the radio turns on and off, or even possibly the lights on your cluster turn off as well as the headlights. Then you are probably dealing with a bad alternator. This is worth noting when we compare a bad alternator vs bad battery.

When you have a bad battery, you will not experience these issues when the car is running, only when the car engine is not started you could notice an instance like this that will be caused by the low battery level. But if the lights flicker when the car is running, it is definitely a bad alternator that’s for sure.

3. Car Won’t Start With Jump

Another in our list of bad alternator symptoms is the situation when the car won’t start with a jump. If the alternator is dead and not working, you will not be able to jump-start the car at all. So, why is this the case?

Well, this is the case because the alternator needs to be producing power so your spark plugs work. If there is not a properly working alternator, it doesn’t matter how many times you jump the car, the car will simply not want to start at all.

There will be no power source to generate enough electricity to keep everything afloat. So, when you have a symptom like this and you think about bad alternator vs bad battery, then you should turn your attention to the alternator because this component is probably the one that causes this trouble to you.

The only way around this problem unfortunately would be to replace the alternator and mount a new alternator in the car. Now let’s cover the next bad alternator symptom.

4. Battery Is Constantly Empty

And the last in our list of bad alternator symptoms is the situation when the car battery is constantly low on charge. So, why is this the case?

Well, this most often is the case because the alternator is malfunctioning and is producing a relatively low current that is not enough to charge the battery and also power the engine. So, you will constantly have a battery that is running on a low charge.

This situation can also be detrimental to the battery itself. So, when you notice that your battery is constantly getting empty even though it is fairly new. You need to focus on the alternator and diagnose the problem. Next in this article, we are going to cover precisely that when it comes to the bad alternator vs bad battery.

Another thing to add before we are done with the symptoms and focus on bad alternator vs bad battery and how to diagnose the problem is that there could be other symptoms as well. If you notice smoke coming from the alternator, you need to turn off your engine and not run your car like this.

Because in some cases, the alternator could catch fire, and the whole car could burn to the ground. So, be really aware of this issue. Now let’s see how you can diagnose the problem when it comes to bad alternator vs bad battery.

How To Diagnose And Fix Bad Alternator VS Bad Battery?

Now let’s move on to testing things out when it comes to a bad alternator vs bad battery. How you can diagnose if one of these components is bad or not? Well, it’s quite simple actually.

For this purpose, you will need a multimeter tool. With this multimeter, you can measure, continuity, resistance, voltage, and other specs. But we are interested only in the voltage in this case.

For this, you will need to set the measurement tool to volts and place the red probe on the positive terminal and the black probe on the negative terminal. For a good battery, you should get around 12V on average more or less 1V. If the reading is lower, you are probably having a bad battery.

Then the next thing you will want to test is if the alternator is charging the battery. For this purpose, you will need to start the engine and repeat the procedure. If the alternator is charging well, the voltage will fluctuate and will range on average between 13 and 15V.

If the voltage is higher, then you probably have a bad alternator that has a bad voltage regulator. Should the voltage be lower, then you probably also are dealing with alternator issues. So, you get the point about how easy is to diagnose when it comes to bad alternator vs bad battery. But have you asked yourself how much money can you expect to pay in order to sort out this problem? Well, that’s what we are going to cover in the following chapter.

Cost To Fix Bad Alternator VS Bad Battery

So, what is the cost to fix bad alternator vs bad battery? How much you can expect to pay in order to sort out this problem with your car?

Well, the cost depends on what could be the problem, the alternator or the battery.

If we are talking about a dead battery, you can expect to pay about $100 to replace the battery. Overall, that is the cost of a good battery.

Bad Alternator VS Bad Battery

On the other hand, if you have a bad alternator, you can expect to pay around $200 if you want to repair it. Or between $350 to $900 if you want to replace the alternator. We are talking about parts only. The cost for the labor will also cost you about $200.

Repairing or replacing an alternator is not cheap and you should be aware of this. Now let’s conclude this article about bad alternator vs bad battery.

Conclusion In Bad Alternator Vs Bad Battery

In this article, we have covered quite a bit when it comes to the bad alternator vs bad battery. We first learned what is an alternator and what is a battery. We covered the basics and then we compared them in the bad alternator vs bad battery chapter.

Then we covered the symptoms for both bad alternator and bad battery and we learned what symptoms these two components produce. Lastly, we covered the diagnostics as well as the costs involved in this work

F.A.Q To Bad Alternator VS Bad Battery

Now let’s answer some frequently asked questions.

What Does An Alternator Do

The alternator is a generator that generates electricity. This electricity then is used to power the ignition as well as other accessories in the car such as the stereo, dome lights, and infotainment.

How Long Do Alternators Last

On average an alternator lasts about 100,000 miles or so. Sometimes, even more, depending much on the manufacturing quality. Usually, the bearings are the first that fails in an alternator from the long use.

How To Tell If Alternator Is Bad

You can tell if an alternator is bad if the shaft is wiggling around when the engine is running. If you start to hear grinding noises. Or if the battery is constantly empty and not charged well enough.

How To Test Alternator

You can test an alternator with a multimeter tool. Just start the engine and turn the multimeter to volts. Then place the red probe on the positive and the black on the negative terminal. You should get on average about 13 to 15V if you have a good alternator.

How Much Is An Alternator

On average a good alternator is about $450. There are cheaper and also more expensive ones. It really depends on the make and model that you have.

Approved Tools

These tools have been tried and tested by our team, they are ideal for fixing your car at home.

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