Hardware Knowledge Sharing

Well, if you do own a car, then you might be knowing or might not be knowing whether the negative terminal should always be disconnected first while removing the car battery. If you are a growing engineer in an automobile section/company, then you must be knowing this fact but if you want to know the reason why negative terminal should be removed first, then it is very simple.

The negative terminal of the battery acts as the ground for the battery. And there are two grounding types in the whole car body: Body Ground and Engine Ground. The body ground of the car is connected to the entire major portion of the car body and the engine group to some part of the engine.

If you remove the positive terminal of the battery first, then it may touch to the body ground of the car which is the very common occurrence as it may touch any part of the car. If the positive terminal of the car touches directly to the ground, then obviously spark will produce as there will be a large current as the positive terminal is directly connected to the ground. As the battery gives power supply to most of the electronic components in the car, the electrical noise generated in the process is enough to damage the ICs in the electronic components of the car.

If you remove the negative terminal of the battery first, then there is no problem even if it touches the body ground of the car. So, it is a safe practice to remove the negative terminal of the car battery while removing the car battery. For the same reason, the positive terminal of the car battery should be connected first while assembly the car battery back to the car.