Learn How to Disconnect Car Battery Properly

There are several reasons why you might have to disconnect car battery , whether it is to change it, recharge it, or work on the electrical system.

Here is how you can disconnect and remove the battery from your vehicle safely

There are a few precautions to take before you disconnect car battery.

Put your car on a flat surface, and pull up the handbrake.

First turn the ignition off then wait a few minutes before unplugging your battery, while the computers is recording the latest information it  will still need current.

Make sure to remove any jewelry you wear on your hands.

Precaution: Take care not to touch both battery terminals at the same with your tools.

Positive and negative car battery

First disconnect the negative terminal

First disconnect the negative terminal, which is often black (indicated by minus (-) sign). The clamp is sometimes placed under a plastic cover. So just lift it up and loosen the nut of the clamp with a wrench, then remove the cable.

Then do the same with the positive (red wire, indicated by a + thicker).

Indeed, the negative terminal, or mass is in contact with the frame of your car, while the positive circulates the current. If this positive terminal comes by inadvertent into contact with the metal chassis of the car while the mass is still connected, it is assured short circuit.

Note: when reinstalling your battery, you will proceed in reverse: First connect positive, then negative terminal.

Remove clamp and remove the battery

Use a pipe wrench to loosen the clamp that holds the battery in place in case of impact.

It’ll just remove the battery from its housing.

Avoid tilting it (it contains acid that can sometimes leak into the batteries used with maintenance).

Disconnect recent car battery

More and more recent car are equipped with modern technology that lock the car or even prevent you from starting it, if you remove the battery without taking certain precautions.

It is an electronic security system that will deprogram your car radio and key. You will then have to return to your car dealer to put back everything in order.

To prevent this problem, it might be necessary to connect a simple 9 volt battery to replace the battery untill you install a new one

Disconnect car battery without losing setting

Before disconnecting the battery, connect the terminals to  a 9-volt battery (Figure 1). Connect the (+) on the (+) and (-) to the (-) the 2 big wires which are on the battery of your car. Do it with an electrical tape in order to keep them connected to the wires coming from the battery (9V).


The main goal here is to only supply the amount of current needed to avoid losing the settings; that is why a very low consumption of 9 volts is sufficient but not for 30 minutes. So make sure there is nothing else turned on in the car, otherwise the 9 volt battery will drain in seconds.

Now you can disconnect the battery and change it

It is only at the end that you will remove the 9 volt battery by removing the wires set by the tape.


Make sure that the wire which are now powered by the 9 volt battery never come into contact with each other or with the body of the car because it will immediately empty the battery and blow fuses too









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