How To Disconnect A Car Battery To Reset The Computer

There are many reasons why people might want to disconnect your car battery. It could be that the batteries need replacement, or the terminals need cleaning. In any case, one of the most common reasons is that they want to reset the Engine Control Module (ECM) which is an onboard computer that controls most of its functions.

By the way, do you know how to disconnect a car battery? This is the quick overview of how to and you can also learn the ways to reset the computer along the way!

1. Locate the Right Terminal
2. Choose the Right Socket
3. Disconnect the Negative Terminal
4. Disconnect the Positive Terminal
5. Getting Out of the Car Battery

Before getting into the subject, I highly recommend you to know the tools you need and understand the aspects of removing a car battery first!

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What Do You Need to Disconnect Your Car Battery?

1. A baking soda and water paste: this will be used to clean out the battery tray and clamps. If you’re storing your battery to be re-used, the baking soda paste can be used to clean that up as well. This step is only required if you notice any signs of corrosion. Corrosion will appear in the form of white and green powder.

2. An adjustable wrench (or pliers): this is required to remove the bolt heads of the battery, make sure the handles are coated with plastic to insulate them and avoid electrocuting yourself. Some batteries, such as GM batteries will require a socket wrench to unscrew the bolts.

3. Gloves: It doesn’t matter how old the battery is. Car batteries are strong enough to electrocute you so it is vital to wear insulated gloves to prevent any such incidents.

4. Zip Ties: Zip ties keep the battery wires from touching and sparking.

5. Goggles: for many, this might seem like an extra measure, but having chunky goggles on your face is a small price to pay for being protected from potential battery acid explosions. The battery and the acid it contains can become unstable at any point so it’s better to be safe than sorry.

5 Cautions to the Disconnecting a Car Battery

1. Remove any Accessories

Metal jewelry, such as rings and watches are good conductors of electricity and can trigger an electric shock. It’s better to remove them before you get started.

2. Work in a Ventilated Space

The battery contains acid, which is likely to give off harmful gases. To avoid inhaling too much of them, it is ideal to work in an open-air space or at least a well-ventilated room.

3. Keep Everything Dry

The slightest amount of water can be catastrophic. Keep your work space completely dry and if you’re living in a place frequented by rain showers, work indoors.

4. Turn off the Power

Make sure your car engine isn’t running. Also check the lights and the dashboard to make sure that everything that uses power is off.

5. Be Careful when Dealing with a Corroded Battery

Before you begin disconnecting the battery, check for signs of corrosion. If the greenish-white powder is widespread, then don’t try to detach the battery yourself. It is ideal to hire a professional to do the job to avoid acid explosions and electrocution.

Is the Battery Location Different for Different Vehicles?

While it’s easy to locate the battery in some vehicles, it’s a little more complicated for others. The battery may be directly under the hood or concealed under a cover. For other vehicles, it may be located towards the back of the car, usually sealed behind the trunk. Others might store the battery under the car floor or below the rear seat.

To locate the car battery, you can either consult the car manual, or if you’ve lost it, you can check different areas of the car. You can also check online with the car brand and model to find out where the battery is located.

Getting Started: 5 Steps to Remove Your Car Battery

Step 1: Locate the Right Terminal

Locate the negative terminal on top of the battery. It is generally covered in black. You will also be able to find a small minus sign near the connector post of the battery. The positive terminal, on the other hand, is depicted by a red covering and a plus sign near the connector post.

Start working from the negative to the positive terminal.

Step 2: Choose the Right Socket

You’re likely to have different sized sockets for different purposes. Select the one which seems to be roughly the size of the bolt head you are planning to unscrew.

Step 3: Disconnect the Negative Terminal First!

Starting from the negative terminal cuts off the flow of current, so it is necessary to start from the negative end.

Attach the selected socket to your wrench and put the wrench on the bolt on the negative terminal. Turn it counterclockwise (towards the left). Within a few turns, the bolt head will become loose.

Push aside the negative connector from the battery so that it doesn’t come into contact with the battery while you’re working on it.

Note: If the cable is stuck to the battery post, don’t pull at it. Get a battery cable remover from your local hardware store to pry it loose.

Step 4: Repeat “Step 3” for the Positive Terminal

Repeat the steps you followed for the negative terminal to disconnect the positive terminal. The positive connector will have some current left even after being disconnected, so make sure it doesn’t come into contact with any part of the car. This can potentially damage other circuits in the car.

Step 5: Getting Out of the Car Battery

Once all the cables have been disconnected, you can decide on what you want to do next:

1. Installing a New Battery

Once you’ve completely disconnected the battery, unscrew the bolts holding it onto the battery tray. The battery will be quite heavy (can weigh anywhere between 30-50 lbs) so be careful when lifting it out.

Using a brush with stiff bristles like an old toothbrush to rub the baking soda paste I mentioned earlier on the battery tray and cables. This will help get rid of any rust and corrosion.

Once the paste is completely dry, you can get on to putting in the new battery. Put the battery on the tray and fix the clamps onto it.

At this stage, you’ll start connecting from the positive terminal and then move on to the negative terminal. Make sure that all the bolts are tightly secured. Once this is done, you can close the car hood.

The old battery can be exchanged for a new one, sold or just given to an automotive manufacturer to be recycled.

2. Resetting the Computer

Once the battery is out, you’re ready to reset the computer. You might want to do this because there is a problem with the diagnostic codes or your engine light keeps flashing.

It is important to keep in mind that resetting the computer should only be treated as a backup plan if there is an ongoing problem with your car system, even after repairs.

Once you’ve disconnected the battery, connect the negative and positive cables together.

The cables should not touch the battery terminals and can be secured with the help of clamps or electric tape.

In around five minutes, the computer will start to reactivate. Make sure you’ve gotten the diagnostic codes checked before you resort to resetting the computer as these codes are most probably a warning sign of greater internal damage.

There is a risk of the car system forgetting basic functions like when the accelerator has been released, but after a single drive, the system should revert to its standard functioning.

Here is the great YouTube video I found for you below:

3. Disconnecting the Car Battery for Storage Purposes

If you’re traveling for a long period of time or don’t intend to use your car for a while, you can remove the car battery to prolong its life.

An unused battery can start to corrode and may need to be replaced when you finally need to use your car. Disconnecting and storing it will prevent it from getting damaged and once you’re ready to use it, just install it back in.

Note: Even despite all these precautionary measures, your car battery will eventually need to be replaced because the average life of a car battery is around four years.

How Can You Properly Store a Disconnected Battery?

Once the battery has been disconnected, check if it’s intact or shows signs of leakages and corrosion. If it’s in good shape, you can store it for later use. Corrosion can be cleaned off with the baking soda paste.

Check the electrolyte level of the cells in the battery. For those below the recommended level, fill them with distilled water till they’re at the right level. If required, you can charge the battery and let it cool down to help the electrolyte levels return to normal.

Take the battery out of the car and store it in a cool place without any moisture/water exposure. Make sure the space is not cold enough to cause the battery to freeze.

Connect a charger to your battery (ask an automotive manufacturer for the charger best suited for your car battery) to maintain its charge while it is stored.

You’re Done!

Congratulations! You’ve reached the end of the process without any serious disasters. Whether you’re replacing an old battery or storing a functioning one, taking the right precautionary measures and following the right instructions will make the job quick and easy.