Home Diagnosis and TroubleshootingElectrical System and Electronics How Work Car VDC Generator – All You Need To Know!

How Work Car VDC Generator – All You Need To Know!

by Jordan Harris
How Work Car VDC Generator

Are you having problems with charging the battery on your vehicle and you are interested in learning how work car VDC generator? Well, if that is the case and you want to learn how this generator works, then you are at the right place because there will be a lot to cover on this topic.

Doing the proper research before you go to the mechanic’s shop to sort a problem out might be a really good idea. Why so? Well, mainly because a lot of mechanics will try to rip you off and take all your money on a repair that doesn’t exist and will make you pay to change a number of components that actually work well in order to squeeze as much money from you possible.

So, knowing how car VDC generator works might be a good idea since you will be able to tell what this component is and what are the costs when it comes to repairing it or replacing it. This is why we are here to help you out when it comes to this problem and explain to you everything you need to know when it comes to the charging system on your car.

First, we are going to learn what is a battery charging system and then we will cover the alternator. Then we will take a look at how work car VDC generator and understand the method of work of this component. Then we will learn the symptoms of charging system failure and we will learn how you can diagnose a bad alternator also known as a VDC generator. So, if you want to learn more, follow along.

What Is A Battery Charging System

Now before we learn how work car VDC generator in a car, let’s take a look at what is the battery charging system. Let’s cover the basics of how the battery is charged up in general. Knowing this will really help you understand more about this system and what could go wrong. So, let’s get into it.

As you probably know every internal combustion engine needs a constant power supply in order to work. Without a constant power supply, the spark plugs will not work and your engine will shut down immediately since there will be no spark to ignite the gas.

And this is why the battery is crucial when it comes to this procedure. The battery is in charge of storing the electricity and helping you start the engine. As well as keeping it afloat and making it work.

The battery as you probably know is a lead acid battery. There are lead plates that are submerged in sulfuric acid. And when the electricity is transferred to it, then this battery is storing this electricity.

This type of battery is not like your electric car batteries (it’s a part of the hidden costs of owning an electric car) which hold a lot of charge. This battery delivers only 12V of power. Which is enough to power up the accessories and also help start the vehicle over. But what creates the power to top off the lead acid battery? Well, more on that we are going to cover next when we will cover the alternator also known as the VDC generator before we learn how this generator works.

What Is An Alternator Or VDC Generator

Now before we dive into how work car VDC generator, let’s take a look at what is an alternator, also known as a VDC generator.

Well, let’s take a look first at the history. Back in the day, generating power for the auxiliaries was rather difficult. There were components called dynamos and they had some drawbacks that didn’t make them stick in the car industry.

During WW2, there was a development of another electricity generation component and this was the alternator. The alternator in simple words is a generator that generates an electric current. How it works we are going to elaborate on later in the article.

What is important for you to know right now is that this alternator started to be mass produced since the 50s and nowadays 100% of the new cars come with alternators.

But, how an alternator looks like? Well, an alternator is a component that is usually mounted on the engine block.

This alternator has a pulley on one side that is connected to the drive belt. Which is also known as the serpentine belt. The serpentine belt is a belt that basically spins the alternator and then this action helps the alternator to create electricity

But how work car VDC generator? How this magic happens behind the curtain and with the spin of the alternator you get enough power to charge the battery and also run the accessories? Well, in the following chapter, we are going to cover precisely that. So, follow along. After that, we will discuss the voltages and also the symptoms of a charging system failure. And you don’t want to miss that.

How Work Car VDC Generator

Since we learned the basics of the battery charging system in your car and learned that the car battery and alternator are the most important components that you need to be aware of. Let’s now take a look at how work car VDC generator, in other words how the alternator works. Knowing this will be really beneficial for you, in case you have problems with the alternator. So, let’s dive into it.

A car alternator as we mentioned previously is a generator. This generator generates an electric current. More precisely, AC current. So, how is this possible?

Well, the AC current is created with the help of the crankshaft of the engine. The crankshaft has a pulley that is connected to the pulley of the alternator with a belt. This belt is known as a drive belt, serpentine belt, and alternator belt.

Inside the alternator, there is a shaft that is spun by this belt and this basically moves the rotor inside of the alternator.

Inside the alternator, the rotor rotates and creates an electromagnetic field with the help of the stator. Thus, creating power in the process.

This electric current is known as AC current or alternating current. And as such, it is relatively unusable. This is why there is a component on the alternator known as a rectifier. This rectifier simply converts the AC current into DC current that the battery and all the appliances inside of the car are using.

This process is really essential when it comes to understanding how car VDC generator works since this is basically the main job of this generator to create AC current and then convert this current into DC current. But what is the right battery charging voltage? More on that next.

What Is The Right Car Battery Charging Voltage

Another thing that we would cover since we learned how work car VDC generator (alternator) is the charging voltage that this alternator produces and charges the battery.

As you probably know, the charging voltage really depends on the rotations of the shaft of the alternator. The stronger it spins, the more power it makes.

But this has to be limited to a certain point in order to avoid cook-offs and destruction of the alternator.

For this purpose, each alternator has a voltage regulator that limits the voltage output of the alternator. This means that the alternator could not produce more power than a certain limit that was introduced from the factory.

Because if it does do so, it could damage the electrical system as well as the car battery. So, this is a really crucial component when it comes to this aspect. But what is the right charging voltage?

Well, the average charging voltage that is considered to be normal is between 13.8 to 14.7 volts at normal temperatures of about 77 degrees Fahrenheit.

At low temperatures at about 20 degrees Fahrenheit, this voltage can jump even high from 14.9 volts to 15.9 volts. But here the plateau kicks in and the voltages cannot get greater than this.

Later on, in the article, we are going to cover how you can measure the voltage of the battery as well as how to determine if an alternator is in good condition. So, if you want to learn more follow along. Since we covered how work car VDC generator, now we can move on to a different topic and that is the symptoms of a failing charging system.

Symptoms Of Charging System Failure

Now as we learned how work car VDC generator, let’s move on and cover some of the symptoms when this generator (alternator) fails.

Knowing the symptoms will help you to determine whether or not in reality the alternator has failed on your car or possibly there is some kind of other problem occurring. So, if you want to learn more about it, follow along.

How Work Car VDC Generator, Symptoms #1: Charging System Warning Light

When the VDC generator fails, you will notice the charging system warning light on the dash appear. Or some kind of message like for example, Service Charging System. Or something similar.

Whenever this happens and you notice a battery light. It means that the level of the battery is not at the recommended levels.

How Work Car VDC Generator

In other words, it is below the recommended threshold of 12V. This can be due to a bad battery. For example one of the cells has died and the battery only produces about 10 or 8 volts.

Or possibly the alternator also known as VDC generator has failed and the battery is constantly empty and without power.

So, when this happens. You just need to grab yourself a multimeter and start diagnosing stuff. Later on, we are going to teach you how to test a battery as well as how to test an alternator. Now let’s move on to the next symptoms since we learned how work car VDC generator.

How Work Car VDC Generator, Symptoms #2: Dead Battery

The second symptom that we are going to cover that is appearing when you have a bad VDC generator is a dead car battery. So, why is this the case?

Well, as we learned in the previous chapters when we covered how work car VDC generator, we learned that this generator is spun by the drive belt of the car and is constantly producing power in order so the engine of the car to run.

So, whenever this generator, or alternator as you would call it, does not work well, the battery will be constantly empty.

The energy produced by this faulty alternator will not be fully sufficient in order for the engine to be able to run properly. And once this is the case, the battery will run on low charge and will die.

Causing premature battery death with a bad alternator is one of the easiest things to do. Even if you purchase a new battery, a very bad alternator will kill it in a few months or even less sometimes. So, be really aware of this symptom because it is really common out there.

How Work Car VDC Generator, Symptoms #3: Engine Has Trouble Starting Or Is Stalling

Now as we learned how work car VDC generator, let’s move on to the next symptom. And this is the symptom when the engine has trouble starting. So, why is this so?

Well, this is the case as we mentioned previously, the battery is constantly on low charge because of the bad alternator and doesn’t hold enough charge to start the car from the first try. You need to keep cranking the battery so enough momentum is created and the car starts.

How Work Car VDC Generator

And this is putting an extra strain on the battery itself because your battery doesn’t want to be cranked and cranked continuously for a really long time.

Also, when the alternator is bad and the battery as well, you will also suffer from stalling issues. These issues will be attributed to the inability of the battery to supply the proper engine work. Remember that the spark plugs need electricity to keep working.

So, if there is no electricity to the spark plugs. Your engine will die. And this often happens on heavy loads because at this point there is an increase in demand for electric current to the spark plugs. So, now we know how work car VDC generator, now let’s move on to the next symptom.

How Work Car VDC Generator, Symptoms #4: Accessories Turn On And Off

Now let’s move on to the next symptom of a bad car VDC generator (alternator). And this symptom is connected to the accessories inside the car.

If you didn’t know, whenever there is no constant flow of electricity, the appliances inside of the car like the radio, and infotainment system could turn on and off.

If this happens in your car, then there is a high chance that this is caused by a bad alternator. Don’t freak out that your infotainment system is broken because the battery and the alternator can cause it to bug out and restart itself.

First, check the battery and the alternator and then move on with the diagnostics if these components are good. Later on, we are going to explain how this is done the right way. Now since we know how work car VDC generator works, let’s move on to the next symptom.

How Work Car VDC Generator, Symptoms #5: Lights Get Dim Or Flicker

Now let’s dive into the next symptom of a bad car VDC generator (alternator) and that is the situation when the lights inside of the car are starting to flicker or get dim. So, why is this the case?

Well, this is the case because as we mentioned previously, the alternator is working below the demanded threshold. And when this happens, there is not enough power to top off the battery and keep all the accessories including the lights in proper working order.

So, if you notice how the lights of the car at night get dimmer and dimmer. Or the interior lights get dim or flicker when the car is running, you just know that there are problems with the alternator and these problems need to be solved as soon as possible.

Because if you don’t try to solve this problem. You risk yourself ending up with a broken car in the middle of nowhere because you didn’t learn how work car VDC generator on time. Now let’s move on to the next symptom.

How Work Car VDC Generator, Symptoms #6: Whining Or Growling Noises

Now let’s move on to the next symptom of a bad car VDC generator and that is the whining or growling noises that could come from the engine bay. So, why is this the case?

Well, this is the case because there is a shaft inside of the alternator that is rotating. And when this shaft loses balance because some of the bearings inside fail, the alternator will start to develop a ton of different noises that will be really unpleasant to hear and will indicate that there is a problem with the car.

So, in these situations, it is best for you to sort this problem out as soon as possible. Now let’s move on to the next symptom.

How Work Car VDC Generator, Symptoms #7: Smell Of Something Burnt

And the last symptom on our list is the burning smell. If you didn’t know, bad alternators are one of the most common reasons for an engine fire.

Especially if the voltage regulator fails the alternator will be pushed to its limits and will eventually fail. And when it fails, it could melt the wires and also cause a big fire in the process.

So, whenever you notice something smoking from under the hood, you need to investigate and if the smoke is coming from the alternator you need to immediately fix the issue before it is too late. So, we learned how work car VDC generator and the symptoms, now let’s move on to how to diagnose this component.

How To Diagnose A Bad Alternator?

Now since we covered how work car VDC generator (alternator), let’s now move on and learn how you can diagnose a bad alternator.

As we mentioned, you can stick to the symptoms like the flickering lights, appliances restarting, and so on. But the most precise way to diagnose a bad alternator is with a multimeter. A multimeter is a tool that you can use to measure voltage and other properties. But for our purpose, you only need to measure voltage.

Turn the multimeter on to voltage and place the black probe to the negative terminal of the battery and the red probe to the positive terminal. A good reading should be around 12.6V. If the level is lower than this, you probably have a bad battery or a bad alternator.

To test the alternator, just leave the probes on and start the engine. Leave the engine to run. The voltage should rise between 13.9 and 14.8 volts. 14.2v is the optimum voltage. Anything below 13 volts can indicate a weak VDC Generator (alternator) that needs to be replaced.

Facts about Vehicle Dynamic Control (VDC) and Electronic Stability Control (ESC):

  1. VDC stands for Vehicle Dynamic Control or Vehicle Dynamics Control, which is the same as electronic stability control (ESC).
  2. ESC has been mandatory on vehicles sold in the United States since 2012.
  3. VDC uses computerized technology to detect wheel slippage before it is evident to the driver and applies countermeasures that the driver cannot.
  4. VDC applies the brakes to individual wheels to counteract slipping and forces the car to turn if it begins to understeer.
  5. VDC continuously monitors steering and vehicle direction to mitigate problems caused by wheel slippage and a loss of traction.
  6. Subaru VDC is a form of electronic stability control that uses a network of sensors to monitor wheel speed, steering-wheel position, yaw rate, and lateral acceleration.
  7. Subaru VDC uses all-wheel-drive to maximize traction and restore vehicle stability.
  8. Nissan and Infiniti’s VDC systems control brake pressure to individual wheels and regulate engine output to help the driver maintain control of the vehicle in both understeer and oversteer situations.
  9. The VDC feature helps a car maintain proper traction when driving in adverse conditions, but it cannot prevent loss of vehicle control in all driving situations.
  10. The driver is always responsible for the vehicle’s safe operation and should adjust speed and driving inputs for the road and weather conditions encountered.


In this article, we have covered quite a bit when it comes to how work car VDC generator. First, we learned what is the battery charging system and how does it work.

Then we covered the VDC generator also known as an alternator and learned its method of action as well. After that, we covered the symptoms of a bad alternator as well as the diagnostics process and how this is done on a car.


Now let’s answer some frequently asked questions.

What Is An Alternator

The alternator is a device that is installed on cars with internal combustion engines. This device is a kind of electric generator built for generating electricity.

What Does An Alternator Do

The alternator is generating electricity. It charges the battery and then this electricity is used to power the ignition system of the engine as well as the internal accessories inside of the car.

Does The Alternator Charge The Battery

Yes, the alternator is charging the battery constantly while the car is running. It always makes sure that the battery voltage is above 12.6V and that the battery is in good health.

What Does An Alternator Look Like

The alternator is a round shape object. Not like a circle but rather cylindrical in shape. It has small holes and through them, you will be able to see some copper wires. Also, the pulley on which the drive belt is attached is clearly visible.

What Is A Dynamo

A dynamo is a special component that is designed for creating electricity. Dynamos were very common back in the day but they were replaced by better components known as alternators.

What Does VDC Off Mean

VDC is light on Nissan vehicles that indicate issues with the Vehicle Dynamic Control system. This is the stability system on Nissan cars. This is basically a traction control system but Nissan branded it as VDC.

You may also like

Leave a Comment