Why Don’t You Connect The Negative When Jumping A Car?

Jumping a car means starting the engine using another car’s battery. This is usually done when the car’s battery is dead, and there is no other way to start the engine. The process is simple: you just need to connect the two batteries together using jumper cables.

Many people think you should always connect the negative cable to the ground when jump-starting a car, but this is not always necessary.

Here’s Why You Don’t Connect the Negative When Jump-Starting a Car

I remember when I had to jump-start my car for the first time, and there was nobody to guide me. Everything seemed to be so confusing, but I remembered one thing: I should never connect the black cable to the negative (-) terminal on the dead battery

The main reason for doing so is to avoid a potential explosion. Car batteries emit hydrogen gas when being charged, which is flammable.

It is usual for sparks to occur when connecting and disconnecting the leads on the battery terminals. Therefore, you want the last negative connection to be away from the battery.

The Right Way To Connect The Cables

To jump-start a car safely, attach a red jumper cable clamp to the positive terminal of the dead car battery. Connect the other end of the same cable, the second red jumper clamp, to the positive terminal on the working (live) car battery.

Attach one black jumper cable clamp to the negative terminal of the working (live) battery. Finally, take the other black clip and attach it to the dead battery’s negative terminal.

Now that all four cables are correctly attached, you can start the engine of the working car. Once the engine is running, remove the cables in reverse order: black, black, red, and red.

Do You Have To Ground The Negative When Jumping A Car?

The quick answer is no; you don’t have to ground the negative when jumping a car. However, there is a reason why it’s a good idea to do so.

Connecting the negative cable to the ground provides a path for the current to flow from the battery to the starter. If you don’t connect the negative cable to the ground, the current will have to flow through the engine block.

Where To Ground Negative Jumper Cable

Most people don’t realize that there is a right and wrong way to hook up jumper cables. If you literally connect the negative cable to the ground, you can damage your car’s electrical system. The best way to ground the negative cable is to find a metal part of the car that is not painted.

Once you have found a good spot, attach the clamp to the metal and make sure it is tight. This will ensure that the negative cable is properly grounded.

What Happens If Jump Start Is Connected Wrong?

When you connect the jumper cables incorrectly when jump-starting a car, it is possible to cause severe damage to the electrical system. If you connect the positive cable to the negative terminal on the battery or vice versa, this can create a spark that could potentially damage the battery or other electrical components.

Additionally, the jump-start will not work if you do not connect the cables correctly and could drain the battery further. For these reasons, it is important to make sure that you connect the jumper cables correctly before attempting to jump-start a car.

Whenever you are unsure of how to correctly connect the jumper cables, it is best to consult with a professional or read the instructions in the car’s owner manual. Attempting to jump-start a vehicle without knowing how to connect the cables correctly can be dangerous and may cause damage to your vehicle.

A Step By Step Guide On How to Jump  a Car

Preliminarily, you’ll need to gather a few things: two jumper cables, a working car, and someone to give you a hand. Once you have those things, you can begin the process of jump-starting your car.

Step 1: Position the working car close to the dead car, but make sure not to touch them together.

Step 2: Open the hoods of both cars and identify the batteries. Once you’ve found the batteries, you’ll see that each one has two metal posts: a positive ( +) post and a negative (-) post.

Step 3: On the dead car, take the red jumper cable and attach it to the battery’s positive post. Then, take the other end of the red cable and attach it to the positive post of the live battery.

Step 4: Now, take the black jumper cable and attach it to the negative post of the working battery. And finally, take the other end of the black cable and touch it to a bare metal surface on the dead car—such as a bolt or the engine block.

Step 5: At this point, you should be all set. Start the working car and let it run for a few minutes. Then, try starting the dead car. If it still doesn’t start, you may need to repeat the process or call a tow truck. But if everything goes according to plan, your car should be up and running in no time.

Frequently Asked Questions: FAQs

Can I Use A Battery Charger Instead Of Jumper Cables?

Yes, you can use a battery charger instead of jumper cables. However, it’s important to make sure you choose the right charger. You’ll need a six-volt charger if you have a standard car battery. But if you have a high-performance car battery, you’ll need an eight-volt charger.

Can I Jump-Start My Car With A Flat Battery?

No, you cannot jump-start your car with a flat battery. To jump-start a car, you need to have enough power in the battery to turn over the engine. And if the battery is completely flat, it won’t have enough power to do that.

What Should I Do If My Car Won’t Start After Jumping It?

If your car doesn’t start after you’ve jumped it, you should first check the battery. Ensure the terminals are clean and the cables are properly connected. But if the battery looks fine, the next thing you should check is the engine. Ensure that there’s oil in it and the spark plugs are working.

What Causes A Car Battery To Go Flat?

There are a few things that can cause a battery to go flat. One of the most common causes is leaving the lights on. If you leave the lights on for too long, it will drain the power from the battery.

Another common cause of a flat battery is a faulty alternator. The alternator is what charges the battery while the car is running. So if it’s not working correctly, the battery will eventually run out of power.

Finally, extreme weather can also lead to a flat battery. The battery won’t have enough power to start the car if it’s too cold. And if it’s too hot, the battery fluid can evaporate, preventing the car from starting.


Jumping a car can be a simple process, but it’s important to ensure you do it correctly. If you’re unsure about anything, be sure to consult with a professional or read the instructions in the car’s owner’s manual.

Attempting to jump-start a vehicle without taking the proper precautions can be dangerous and may cause damage to your car. 

With a few supplies and the guide above, you can jump-start your car in no time. Just be sure to take the necessary precautions and follow the instructions carefully.

If at any point you feel unsure, you should stop and ask for professional help.