How To Connect Car Battery

If you have an old or dead battery in your vehicle, you’ll need to replace it with a new one. While removing the old battery and connecting the new one is a simple task, you need to follow the right steps to complete the process safely and effectively.

Otherwise, you can end up with a wide range of electrical issues in your vehicle that can also lead to expensive repairs. That’s why we have come up with this guide that will help you remove the old battery from your car and connect the new one correctly.

How To Connect Car Battery: A Step-by-Step Method

If you need to replace your car’s battery, then make sure that you follow the steps listed below to complete the process safely.

Step 1: Ensure Your Safety

The first step is to ensure your personal safety as you don’t want to hurt yourself. Start the process by parking your car in a flat and dry place and turning on the parking brake. Turn off the ignition and open the hood. If the vehicle is still warm, wait for 10 to 15 minutes to let it cool down.

Keep in mind that many car batteries contain battery acid, which can lead to skin burns. So, make sure that you wear protective gloves and safety goggles. It’s also important to confine long hair and not to wear loose clothes.

Important Note: Never try to remove your car’s battery when the engine is on. It can lead to a high-voltage spike in the vehicle’s electrical system, which can damage the charging system and/or electronic modules.

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Step 2: Locate the Battery

Once everything is ready, read the user manual of your vehicle to find out the location of the battery. It’s typically located on the right side of the engine’s bay under the hood. Your car’s battery will have two large cables (red and black) connected to it.

The black cable will be connected to the negative terminal, which will have a “minus” sign. The red cable will be attached to the positive terminal, which will have a “plus” sign.

Step 3: Remove the Battery Cables

After locating the battery, the next step is to remove the cables from the battery terminals. First remove the plastic/rubber caps mounted on the ends of the cables, connected to the battery.

After that, pick up the wrench that fits the bolts and nuts securing the cables. Unfortunately, different vehicles can have different nut and bolt sizes and it’s not possible to write down the exact wrench size you’ll need. So, we recommend you bring the entire wrench kit you have to pick up the right tool.

Once you have the correct size wrench, use it to loosen and disconnect the black cable attached to the negative terminal of the battery. Then do the same for the red battery cable attached to the positive terminal.

Once both cables are removed, push them far away so that they don’t come in contact with the battery terminals. You can also use a rag to cover the cables and prevent them from contacting the battery.

Place the bolts/nuts (and washers if any) in a safe place so that you can easily access them while installing the new battery.

Step 4: Remove the Battery

Now, remove the old battery from the tray so that you can install the new one. But before that, you’ll need to remove the clamp securing the old battery in place. It’ll also have one or two bolts that you’ll need to loosen and remove using a socket wrench.

After that, pick up the old battery using your hands and place it on a flat surface. Be extra careful while lifting the battery, especially if it has liquid. It’ll be heavy and you’ll be surprised by its weight if you have never lifted a battery before.

Step 5: Clean the Battery Tray

If your old battery has corrosion on its terminal, you might also find the residue of that corrosion buildup on the battery tray and clamp and/or at the end of both negative and positive cables.

You’ll need to get rid of that corrosion properly so that it doesn’t affect the performance of your new battery. You can use a wire brush for this. Make sure that you wear a face mask before performing this step to avoid breathing harmful particles.

If the wire brush doesn’t remove the corrosion properly, consider using corrosion prevention spray or cream for the same purpose. These products are known as battery terminal protectors and you can easily buy them from a local auto parts store.

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In addition, you can also use a mixture of water and baking soda to remove corrosion buildup. 

Once you have cleaned the battery tray, clamp, and cables, make sure that you dry them using a microfiber cloth. Wait until they’re fully dry and then move to the next step.

Step 6: Install the New Battery

Pick up the new battery and place it carefully in the battery tray. Then install the clamp back in its place and properly tighten its bolt(s) using a socket wrench.

Attaching the clamp is critically important to protect your car’s battery and prevent it from moving/vibrating while driving. So, make sure that you don’t skip this step.

Step 7: Connect the New Battery

Once the battery is in place, apply dielectric grease to its terminals. You want to apply grease to help the battery terminals make a better connection with cables. But make sure that you don’t apply too much dielectric grease as it’ll increase the risk of cables being slipped off.

Pick the washers and bolts and insert the washers into the terminals. Next, grab the positive battery cable and secure it to the positive terminal using the bolts. Do the same for the negative battery cable. Tighten the cables properly but avoid over-tightening them.

Important Note: Always remove the negative cable first, while disconnecting the battery. While reconnecting the battery, make sure that you attach the positive cable first.

Step 8: Test Your Installation

Don’t close the hood of your car after connecting the new battery without testing it. Go inside your car and turn on the ignition to see if your vehicle starts and gets the electrical supply. If everything works fine, you have successfully connected the battery.

If your vehicle doesn’t start and you don’t see any light on the dashboard, go to your battery and check the connections properly. After that, try to start the car again. Make sure that you don’t attempt to start the vehicle more than two times in five minutes.

If it still doesn’t work, there’s some problem with the new battery. You can also use a multimeter to find out whether it is charged or not.

Risks and Precautions to Keep in Mind While Connecting the Battery

As you can see, connecting a car battery is not a difficult task. But it’s all about carefulness and safety procedures. A car battery has a massive amount of current and if a short circuit happens, it can damage your vehicle’s electrical system badly.

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Use the list of tips discussed below to avoid any unwanted scenario.

  • Always read the user manual of your vehicle to take safety measures before you start the battery replacement process.
  • Place the car on a dry and flat surface and in a well-ventilated place.
  • Keep any sparks and flames away from your car’s battery (both old and new). Never smoke near the battery.
  • Avoid direct contact with the battery acid.
  • Remove any metal jewelry, such as bracelets and rings, you’re wearing.

FAQs About How to Connect Car Battery

Why Do You Connect the Positive Terminal First?

You should always connect the positive terminal first because the positive cable won’t arc if your tool (spanner or wrench) touches the vehicle’s body during the tightening process. If you connect the negative first and then move to the positive, there will be a chance that it’ll arc through you, giving you a nasty shock.

Do You Hook Up Red or Black First?

Red is the positive cable and black is the negative one. So, you should always hook up the red cable (the positive one) first while connecting the battery. But when you’re disconnecting the battery, always remove the negative cable (the black one) first.

Final Words

Removing the old car battery and installing the new one doesn’t have to be a difficult task. It’s a bit tricky but you can complete the process effectively if you follow the right steps.

We hope this guide has helped you understand how to connect the car battery, without needing to take your vehicle to the mechanic. Make sure that you ensure your personal safety before starting the process and follow each step carefully to complete the process without any hiccups.