Which Battery Terminal To Disconnect When Working On Car?

Hi, I'm Luis Johnson, an automobile technician, and power equipment professional. By profession, I'm a businessman and operate a car workshop. I have created this...Read more

Which battery terminal to disconnect when working on car? Well, it’s the most common question that pops up in many people’s minds while working on their car. And the answer is the negative terminal.

Always remove the negative cable, no matter what type of work you’re performing in your car. Why so? That’s because the negative terminal is attached to a car’s chassis, and working without removing it can cause electrical shock and serious damage to your car.

Removing the wrong terminal can damage the fuse, car computer, or even the battery itself. This article explains what can happen and why you should not remove the wrong terminal from your car. Stick around.

What Type Of Car Work Requires Battery Terminal Removal?

It would be best if you disconnected the battery terminal while working on any electrical components of your car. So, what exactly does the electric component imply? Well, almost all modern automobiles work through the combination of several components, such as

What Type Of Car Work Requires Battery Terminal Removal

Removing the battery terminal is a must if you intend to work on anything related to these components to avoid electrical shock and damage to your car.

Hence, when you remove or disconnect the negative cable of the battery, there is no risk when working on an electrical component.

Moreover, not disconnecting the battery terminal can cause several issues, including car damage as well as injury issues.

Which Battery Terminal To Disconnect When Working On Car

When it’s about working on a car’s electrical components, and it’s required to remove the battery terminal, remove the negative terminal. Disengaging the accurate battery terminal can reduce all types of horrible situations.

Which Battery Terminal To Disconnect When Working On Car

Why will several conditions happen? The negative terminal, also known as a ground strap or cable, is connected to the car’s chassis to ensure grounding. And when you remove the positive cable instead of the negative one, spark and flame issues can happen.

Spark and flame issues can happen if the positive terminal touches your car’s chassis in any way. This is because removing the positive cable first instead of the negative one can sometimes easily touch the car body through your metal spanner or wrench.

After that, it’ll be like connecting both positive and negative terminals together, which can lead to serious and unpredictable incidents.  As a result, when you don’t disconnect the right battery terminals and start working with your car, battery power will surely trigger many problems.

Some of the issues you’ll face are:

  • Short-term critical issues
  • Damage to electric components
  • Issues with your battery
  • It might cause a fire or several unpredictable occurrences
  • Not disconnecting the negative terminal can also injure you significantly

If you never want to go through such conditions, it’s always essential to disconnect the negative terminal before beginning your work. However, if you don’t know the battery terminal removal process, I can help. I’ve provided a step-by-step guide in the section blown:

Arrange All The Necessary Gear

When you’re about to perform any car or electric component, arranging all the necessary gear is a must. Here are some of the stuff that you need to arrange:

Arrange All The Necessary Gear
  • Safety glasses and gloves
  • Wrench (10-millimeter open-end wrench)

Turn The Ignition Off

Once you have all the tools and safety equipment, it’s time to turn off the car if it is turned on. Never try to disconnect the battery terminal with the engine running.

Turn The Ignition Off

Find the Battery

All you have to do is locate the battery. Most car batteries are kept under the hood, so lift the hood and find your battery. However, if you are not sure about this, check your vehicle’s manual for the actual placement.

Find the Negative Terminal

Once you locate the battery, find the negative and positive cables. Most car batteries have the (+) and (-) symbols above the terminals. The cable or cap may also be used to determine which terminal it is; the red terminal is positive, and the black terminal is negative. Moreover, when you identify the negative cable, you can easily do the ground wire your car battery for a consistent eclectic flow. Just make sure that you know where to connect the ground wire of your car battery.

Loosen the Nut and Remove The Terminal

Now use the 10-millimeter open-end wrench (most car batteries have 10-millimeter bolts) to loosen the nut. When the nut is loose enough, simply remove the terminal completely.

Loosen the Nut and Remove The Terminal

Note: Once you’ve removed the negative terminal perfectly, you can now start your car-related work. However, be careful that the negative and positive terminals shouldn’t touch each other.

What Will Happen When You Remove the Wrong Terminal?

Now that you already know why you should remove the negative terminal first, it’s time to discuss what happens when you do the opposite. Follow the section below to learn what will happen when you do the opposite:

What Will Happen When You Remove the Wrong Terminal

Injury Issues

The very first issue you’ll face is one that threatens your safety. You will face short circuits and sparking issues, which can cause significant damage.

Also, while removing the positive terminal before the negative terminal, a huge spark can happen if you mistakenly strike any metal with the negative terminal.

Car Damage

Not only will you have safety issues, but removing the wrong battery terminal can also cause damage to your car. Removing the wrong terminal can trigger unnecessary voltage flows in your vehicle, leading to damage to electrical components. The scariest thing is that removing the wrong terminal can also cause an explosion.

Note: If you don’t want to end up with an injury as well as losing your entire car, always pay double attention to the battery terminal removal process.

When Should You Remove Both Positive and Negative Terminals?

Well, you don’t have to remove both the positive and negative terminals to work on your car. But anytime you find that the battery is not working, you can remove both terminals to check the battery.

When Should You Remove Both Positive and Negative Terminals

Also, when the battery is old and needs to be replaced, you must disconnect both terminals. In addition to replacing a faulty battery, disconnecting the terminals can help keep the battery in good condition if you don’t intend to use the vehicle for a long period of time.

Frequently Asked Questions

If you’re not familiar with the battery terminal removal process, it’s common to have many questions. Therefore, I’ve included this section, where you’ll find some of the frequently asked questions and their answers. Have a look:

When Should You Disconnect The Battery Terminals?

It’s obvious that you’ll not remove the battery terminal from your car for any unusual things with car’s electrical components. Basically, you need to disconnect terminals for two reasons:

For Maintenance:

It would be best if you disconnected the battery while working on your car, as its voltage can damage the car and cause injury.

To Replace Or Recharge The Battery:

Another reason to detach the battery connections is when the battery has to be replaced or recharged.

Will Disconnect The Negative Terminal Cause A Battery Drain Problem?

Whether you connect or disconnect the negative terminal, a car battery will run out of charge with its self-discharge mode even if you’re not using it.

All car batteries have a self-discharge rate of 5–15% per month, and there’s practically nothing you can do about it. On the other hand, if you leave the car for a long time with the negative terminal connected, the discharge rate will increase.

What Are The Car Electric Components That Are Powered By Battery Power?

Battery power is used to power all of the electric components on a car. Here are some of the components:

  • Electrical motor
  • Heating element
  • Sensors
  • Brake
  • Headlights
  • Traffic lights, air conditioning system
  • Interior lights and so on.

There are many more elements that require electric power to keep several cars’ electric components running.

Closing Thoughts

Now that you know which battery terminal to disconnect when working on car and which one is not. Always remember to disconnect the negative terminals, as they continue to flow voltage or current even when the engine is turned off.

It’s always mandatory to remove the negative terminal when you’re working on a car.

Moreover, it’s not recommended to disconnect the positive terminal unless you’re replacing or recharging the battery. Simply follow the step-by-step method while disconnecting the battery, and be sure never to connect both the positive and negative terminals together.

Hi, I'm Luis Johnson, an automobile technician, and power equipment professional. By profession, I'm a businessman and operate a car workshop. I have created this site Batteryquery to help people purchase the right battery for their vehicles. The reason behind creating this site is to help my customers purchase the right car battery who often purchase the wrong one due to their lack of knowledge.

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