When replacing a car battery, should the positive or negative terminal be removed first?
2 Answers
When replacing a car battery, the negative terminal should be removed first, followed by the positive terminal. It's important to understand that the negative terminal of a car battery is connected to the vehicle's body. Since the body is made of metal, the entire vehicle is essentially connected to the negative terminal. This means that the moment the negative terminal is disconnected, the car's electrical circuit can no longer form a complete loop. Removing the positive terminal first is not advisable because the wrench itself is metal and conductive. If you accidentally touch any metal part of the car while removing the positive terminal, it's equivalent to connecting the battery's positive and negative terminals directly. This can not only cause a short circuit in the car battery but may also lead to sparking in severe cases.
I remember when I last replaced my car battery, it was almost a disaster. I initially tried to remove the positive terminal, but the wrench slipped and touched the engine metal, causing a sudden spark that scared me into letting go. Later, I learned the correct sequence: you must first remove the negative terminal—the black cable. Since the entire car body is grounded, acting like a big negative terminal, if you remove the positive (red) terminal first, any tool or hand touching a metal part will create a direct short circuit, causing a surge of current. At best, it could burn the battery cables; at worst, it could start a fire or injure you. When reinstalling, reverse the order: reconnect the positive terminal first, then the negative. A regular wrench will do for the whole process, but be careful not to let the loose cables touch the battery metal. I once helped a neighbor replace his battery, and he made a similar mistake. Now he always reminds himself: when removing the battery, black first, then red—safety first. It’s a simple task that takes just minutes, but ignoring the sequence can be costly. A damaged battery is expensive to repair, so it’s better to do it right from the start.
