How To Disconnect Car Battery Terminals Safely

The battery is arguably one of the vital parts of a car. For this reason, it needs regular maintenance for optimum performance. So, if you're looking to learn how to disconnect car battery terminals safely, stick along for easy step-by-step directions.

A car battery is solely responsible for starting the car and providing power to electrical systems like the stereo or lights. That said, it may stop working overtime, prompting the need for cleaning, maintenance and even replacement.

While some people would prefer going to a local auto parts store or a mechanic to get the battery checked, learning how to disconnect a car battery by yourself is super easy. In addition, you get to save some bucks in the process.

But first, what would prompt you to disconnect your car's battery?

When Is It Necessary to Disconnect Car Batteries?

You may need to disconnect your car's battery when:

  1. Performing regular maintenance - Depending on the maintenance type, you may be required to disconnect the battery beforehand. This ensures safety for your vehicle and yourself by minimizing the risk of electrical issues.
  2. Recharging the battery - In some cases, when a dead battery can't be charged while in its holding tray, you will be required to disconnect it first.
  3. Replacing the battery - Car batteries need to be replaced every 2-5 years, depending on other variables. In this case, it's mandatory to disconnect the old battery to replace it with a new one.

How Do You Safely Disconnect A Car Battery?

Disconnecting a car battery can seem daunting, especially if you've never tried it before. However, as you'll see in this guide, it is an easy process that every car owner should know.

car battery

Tools Required:

  • An adjustable or socket wrench
  • Safety equipment

Step 1: Turn Off the Ignition

Before starting the battery disconnection process, the first step is to ensure that the ignition is off. Attempting to disconnect the battery when the car is running is dangerous for you and the electrical components therein.

In addition to turning off your car, it's advisable to use safety equipment like safety goggles for eye protection and gloves.

Other tips to enhance safety include leaving the driver's door open if the car locks when removing the battery. Also, confirm that the car is in the "Park" position for automatic vehicles and the first gear for manual ones.

Step 2: Find Your Car's Battery

The second step is to locate the battery. Most vehicles have the battery safely tucked under the hood. Press the hood button or pull the lever to open the hood. You will find the button near the steering wheel but below.

If the battery is not in the hood, chances are it's tucked in the trunk of your car. However, first, counter-check this information on the owner's manual. In addition, you will find recommended steps to gain access to the battery.

Step 3: Locate the Negative and Positive Terminal

This next important step involves locating the negative and positive terminals of the battery. The negative terminal will have a "-" minus sign, while a "+" plus sign will indicate the positive terminal.

Depending on the battery, you may find a black plastic cap to mark the negative terminal and a red plastic cap for the positive terminal. Remove the plastic caps to access the battery cables.

Step 4: Disconnect the Negative Terminal

Using an adjustable wrench or socket wrench, start by disconnecting the negative battery cable. It would be best to have a wrench kit with different socket sizes, so you have options to choose from.

Place the wrench on the nut holding, twisting and turning it in the anticlockwise direction to loosen it. This will help disconnect the negative battery cable. Once you have removed the connector cable, push it far aside and ensure it doesn't come into contact with the battery.

You may find that some batteries have the cables attached or seized to the battery post or tray. If your car has such a design, you will need a battery cable removal tool to disconnect the cables. If so, check with the manufacturer or local auto parts store to find out if they have the tool.

Step 5: Disconnect the Positive Terminal

Now it's time to disconnect the positive cable. Ideally, you will use the same way to disconnect the negative connector. Once disconnected, push the cable far away, ensuring it doesn't touch the battery at any one point.

You also want to ensure that the socket wrench doesn't touch the positive and negative terminals simultaneously. Although the battery is dead, there may be residual electricity enough to short the battery and create a spark.

So, you want to avoid any sparks around the engine compartment and battery in general. The sparks may damage the car's electrical system and engine control computer.

Step 6: Loosen the Battery Strap/Clamp/Bracket

Now that the battery cables are disconnected, you will need to remove the clamp on the battery tray to remove the battery. The battery tray is where the battery sits to ensure safety and security.

You will need to use a wrench and an extension to remove the nuts and lift the battery.

Step 7: Remove the Battery

Yaaay!!! Congratulations, the battery is free. You can use your hands or the handles on the battery(if present) to lift it from the tray. However, keep it level when lifting to avoid sloshing the acid inside.

Place the battery on a flat, level surface and away from the vehicle. Be sure to anticipate the battery weight since car batteries are quite heavy. Now, you can perform maintenance on the battery or replace it with a new battery.

Safety Tips You Should Know Before Disconnecting the Battery

Below are tips you should remember before disconnecting a car battery.

  1. Avoid wearing jewelry like rings, watches or bracelets - This is because a car battery stores electric charge and could cause an electric shock when in contact with a metal part.
  2. Remove the car battery in an outdoor space - Batteries hold acids that let out harmful gases. For this reason, working outdoors in an open area greatly minimizes your exposure to these harmful gases. Also, remember to wear eye protection.
  3. Work in a dry area - It's also important that you work in a dry area rather than one that is damp or has water close by.
  4. Beware that your settings may reset or go back to default - Removing the battery terminals will cause your radio or clock settings to reset. In addition, you may need to enter your radio code to set it up.

How To Clean Battery Terminals

When doing regular maintenance, you may notice a bit of corrosion on the battery terminals. This is because hydrogen gas is released from the acid inside the battery.

Follow the steps below to clean the positive and negative battery terminal and the battery cables.

What you'll need:

  • Baking soda
  • Water
  • Gloves
  • Petroleum jelly
  • Pipe cleaning wire brush
  • Wire cleaning brush(cup style)
  • Anti-corrosion grease


  1. Add 1 part (a tablespoon) of baking soda to 1 cup of water to make a cleaner.
  2. Use the pipe cleaning wire brush, dipping it into the cleaner, to clean the interior of the positive and negative connector cables in contact with the terminals.
  3. Use the cup-style wire brush to clean the terminals. A toothbrush will do if you don't have the specific brushes.
  4. Apply some force to ensure you get rid of all the grime, dust, corrosion and debris.
  5. Spray a bit of water on the terminals once all the corrosion is gone. Then, use a cloth or towel to dry it down.
  6. Apply petroleum jelly on the terminals for lubrication and prevention of corrosion. You can also use anti-corrosion grease to prevent corrosion.

Note: Cleaning the terminals of a swollen, leaking, or visibly damaged battery will not do any good. Instead, you will need to get a new battery for replacement.

Frequently Asked Questions

1. Which battery terminal should you disconnect first?

You should disconnect the negative terminal first.


Disconnecting the negative battery terminal first reduces the risk of sparks, which can cause the battery to explode. This is dangerous and poses a threat to you and your car.

2. What happens if you disconnect the positive terminal first?

Disconnecting the positive cable first could result in an electrical short, harmful to yourself and the battery. However, remember to connect the positive connector cable first and then the negative cable when reconnecting your battery. This will help prevent short circuits.

3. How long will the car battery stay charged when disconnected?

A disconnected car battery will hold its charge for up to 6 months. However, it's advisable to charge it every 12 weeks and keep it in a safe and secure area. In addition, ensure to use zip ties or a battery disconnect switch to prevent the negative cable from touching the battery if disconnected.

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