Which Battery Cable to Connect First? (Correct Order & Why)

When it comes to changing your battery, jumping a car, or hooking up a battery charger, you need to know the proper order to connect the cables. But if you don’t, you’re not alone. It’s a common question and one that has a simple answer.

By reading this article, you’ll learn which battery cable to connect first when installing a new battery and why, but also the importance of doing it right when jumping a car. So keep reading, and your battery will be properly connected in no time!

Let’s dive into it!

Positive or Negative First When Connecting A Battery?

When connecting a battery, you always start with positive, then negative. If you want to disconnect a battery, you do it in the reverse order, negative first, then positive. The reason for this is not to create a circuit. The same applies when connecting a battery charger and make sure it’s powered off when connecting.

Some say it doesn’t matter because there’s no circuit being made when only one cable is attached. And while that is true, connecting the negative first means the circuit will be completed as you try to connect the positive. But why is that a bad thing? Let’s find out.

Why Do You Connect The Positive Terminal First?

The main reason why you should connect the positive terminal first is that it reduces the risk of sparking. If you were to connect the negative terminal first and then accidentally touch the positive terminal with the wrench or some other metal object, it could cause sparks.

These sparks could potentially ignite the hydrogen gas that a battery emits when charging, causing an explosion. So, to be on the safe side, always connect positive first! 

How To Tell Which Is Positive And Negative On A Car Battery?

On a car battery, the positive terminal is usually marked with a plus (+) sign and may also have a red cap/ring around it, while the negative terminal is usually marked with a negative (-) sign. Another way of telling is by looking at its size. The positive terminal is usually larger than the negative.

What Happens If You Put The Battery Cables On Wrong Sides?

Putting the battery cables on the wrong side will reverse the current flow, making the battery try to compensate the negative volts into a positive charge. This results in a huge surge of power and the battery overheating, which can seriously damage the battery, electrical components and even yourself.

Needless to say, this should be avoided at all costs. And depending on certain factors, the damage may be severe and irreparable

How to Change a Battery

Now that we know which battery cable to connect first, let’s go over the proper way to change a car battery.

  1. Park your car in a safe and well-ventilated area. 
  2. Turn off your car and pop the hood. 
  3. Find the battery and remove the negative (-) cable clamp from the negative terminal first. To do this, you’ll need a wrench to loosen the bolt. Once it’s loose, pull the cable off.
  4. Next, remove the positive (+) cable clamp from the positive terminal. Again, use the wrench to loosen the bolt and then pull the cable off. 
  5. Take the old battery out and put the new one in its place. Make sure it’s securely in place. 
  6. Now it’s time to connect the cables back on. As we said before, always start with the positive terminal first. Use the wrench to tighten the bolt, and then move on to the negative terminal. 
  7. Close the hood and start your car. Let it run for a few minutes to make sure everything is working properly.
  • If you can’t find the battery, refer to your owner’s manual.
  • Note that some vehicles have the battery located in the trunk rather than under the hood.

And that’s it! You’ve successfully changed your car battery. Make sure you tighten the bolts enough and clean corroded battery terminals so you don’t end up with loose battery cables.

Which Battery Terminal To Connect First When Jumping?

When jumping a car you first connect the clamp of the red (positive) jumper cable to the positive terminal of the dead battery and the other end of the red cable to the positive terminal on the working battery. Do not under any circumstances connect the negative cable clamp to the dead battery’s negative terminal.

As you can see, you also connect the positive terminal first when jumping a car as you do when installing a new battery. However, when it comes to jump-starting a flat battery, there’s always something you need to remember when it comes to connecting the negative jump lead.

That is, when jumping a car you should always connect the negative lead to an unpainted metal surface, preferably as far away from the battery as possible. This can be the body, frame, or engine block. The reason for this is also to avoid sparks.

Also read: 5 Dead Car Battery Tricks To Get You Back On the Road

In what Order Do You Put Jump Leads On A Car?

  1. Connect the cable clamp of the positive (red) jump lead to the positive (+) terminal of the dead battery.
  2. Attach the other end of the positive (red) jump lead to the positive (+) terminal of the working battery.
  3. Next, take the negative (black) jump lead and attach it to the negative (-) terminal of the working battery.
  4. Attach the other end of the negative (black) jump lead to an unpainted metal surface away from the battery, such as the chassis or the engine block. Under no circumstances put the negative cable clamp on the negative terminal of the dead battery.
  5. After starting the car, you remove the jump leads in the reverse order you put them on.

If your car won’t start with jump, here’s why!


Installing a new car battery or jumping a car may seem like a daunting task, but it’s actually pretty easy to do!

By reading this article, you will learn everything you need to know to connect the battery correctly the next time you have to change the battery or jump-start a car. Just be sure to take all proper safety precautions before getting started.

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Rickard Cefalk

Rickard is the owner of Caraspect.com and a dedicated and avid do-it-yourselfer who has always enjoyed working on his own vehicles since childhood. He now devotes his time to sharing his expert knowledge of car maintenance and other car-related information through his website.

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