How to Test Alternator by Disconnecting Battery? [Step by Step]

A leaky diode can result in alternator failure. And whenever you see the warning light or the CHARGE icon popping up, we are sad to tell you that your alternator might be faulty! But if you are having trouble and yet to find if the alternator is defective or not, there are ways to ensure it!

One of the easiest ways to learn about it is by disconnecting the battery. Have you ever learned how to test the alternator by disconnecting the battery? No worries, we will discuss it here!

Make sure you use the process only when you do not have a voltmeter. This method is a bit risky and so, you have to go through the safety section first! 

How to Test Alternator by Disconnecting Battery?

Testing the Defective Alternator: Disconnecting the Battery

Here are some easy steps to help you check your car’s backup! Have a look and make your life easier!

Step 1: The Perfect Parking

To test the alternator of your vehicle, in this process, you have to disconnect the battery. The first step for the process is to take the part to a safe place. Make sure that the parking place is even. It is better to get it in a public place but certify that the place is safe.

If you want, you can settle for a driveway to park your car. Keep everyone away from the car. Take a look at your pets. Don’t let them come near as you are going to work with the battery here.

Step 2: Open the Hood

Once you have placed your car in an even place, you have to deal with the car hood. Get your hands on the hood and open it up. While doing this, you have to ensure that the car is standing in a safe and stable position. If the car is not stable, there can be possible accidents happen. So, double-check it for your own safety.

Step 3: Start the Engine

When you have already opened the hood, it is time for you to get inside the car. Precisely, you have to go through the driver’s seat in this step. Your work here is to start the engine so that you can test the alternator. For checking it, start the engine carefully. We already guess that your alternator is damaged or there are some issues with your alternator.

Otherwise, we won’t be having this conversation! As the alternator is damaged or has issues, starting the car engine won’t be as smooth as it always is. Try harder to start the car engine here.

Step 4: Clean the Battery

Once you can start the engine, you can leave the driver’s seat. Make sure that the engine doesn’t stop after starting. When the car has started running, you have to run back to the battery of your car. This is where you have to work now!

In most cases, if you are checking the battery after so long, there will surely be corrosion or debris around the battery. You cannot go on with your work without cleaning up that space. So, first, get a brush and clean up the mess and dirt that you see around your battery. And if the battery is not in the right condition, check out the best battery and pick up one for your vehicle!

Step 5: Disconnect the Positive Terminal

When the battery is cleaned, you are prepared for checking the alternator. In this process, we will learn how to test the alternator by disconnecting battery positive or negative. So, all you need to do here is search for the positive terminal there. Once you have found the positive terminal of the battery of your car.

You have to get your hands there and disconnect the terminal you found. While doing it, you must ensure that the car battery should keep running. In this running situation, you have to disconnect the car battery’s positive terminal.

Step 6: Test the Alternator

Now, your only work is to check if the car engine is running like before or not! This is how you check the alternator by disconnecting the battery! When you have unplugged the battery, you have to check if the car is running or not.

If it is running then you have finished checking the alternator. It is in perfect condition! So, whatever the problem you are facing is not related to the alternator.

On the other hand, if the car doesn’t run or stops running then you have to understand that there are issues with the configuration of the alternator. And when there are issues with the alternator’s configurations only then it cannot provide the necessary power to the engine.

Testing Alternator by Battery Disconnection: Is it safe?

Yes, you have learned how you can test the alternator by disconnecting the battery but there are some other factors to keep in mind. First of all, you must learn about the alternator. This works for powering the engine when the matter is out from your running car engine.

In short, it works as a generator. Your car battery helps in maintaining the motor system by working with the electricity flow. But while doing this, if you disconnect the battery, the alternator will be the backup generator for your car. And it works for producing high power electricity for your vehicle. And after the high voltage energy is produced, it starts flowing to all the electrical compartments of your car.

When this happens, the temperature of your car and the compartments will increase. If the temperature increases a lot, there is a chance of overheating. Overheating can anytime result in damage to the electrical compartments and the tools of your car.

On the other hand, if there is too much additional power generated, the components of the vehicle can burst too! Eventually, you have to replace a lot of electrical parts of your car if any accidents occur. We are not telling you that assuredly there will be accidents. But there is always a chance of unwanted mishaps. Who wants to bear the loss?

Safer Methods to Test the Alternator

Search for a multimeter for testing the alternator. If you don’t have it, buy one. Gears like the voltmeter and tire pressure gauge must be in your garage if you own a car. Check the best tire pressure gauge for racing and buy one of these too!

First, go through the engine and turn it on. Keep all other accessories switched off in this case. And use the multimeter to test the battery. The voltmeter will help you learn about the battery terminals by reading them.

You are free to turn on all other electrical components after you have taken the reading. And once again, take a reading of the battery. This will help you in learning about the difference between the readings.

The first reading here should be 14v and the second reading should be 13v. However, if you see readings that are different, you have to understand that the alternator is not in good condition. Take it to a professional and work on it to get it back in the previous condition.

Video: Battery or dead alternator test?

Wrap Up

There is nothing worse than losing the backup system of your car! And as soon as you know that there is something wrong with the alternator, you must fix the problem. But first, you have to know if your alternator is actually defective or not!

The steps we have mentioned above are the easiest way to check the alternator’s condition. However, keep your safety first, always!

About Jeremy

Hello! My name is Jeremy Bloomberg. I have been passionate about carpentry and DIY. Over the years, my passion slowly turned into expertise and wider knowledge about electronics. I’ve been involved in numerous projects, both professional and personal. I want to share all I have learned with you. Welcome!

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