Should the Positive or Negative Terminal Be Disconnected When Cutting Power to a Sedan?
2 Answers
When cutting power to a sedan, the method for choosing between the positive and negative terminals is mainly as follows: To save space, cars generally use a single-wire system, where the negative terminal of the battery is directly connected to the vehicle frame, and the negative terminals of onboard electrical devices can be connected to the body with a nearby wire. Therefore, when power needs to be cut, simply disconnecting the negative terminal of the battery is sufficient, eliminating the risk of wires sparking. Additional Information: Because disassembly tools are typically made of metal, if a metal tool touches a metal part of the car body while disconnecting the positive terminal—effectively connecting the positive and negative terminals directly—a circuit is formed, which could melt the terminals or even cause a fire in severe cases. Since metal tools conduct electricity, holding them directly in hand could also pose a danger. Therefore, disconnecting the negative terminal is safer.
I was often asked this question when repairing cars, and experience has taught me to always disconnect the negative terminal first. Why? Because the negative terminal is directly connected to the entire car's frame, which acts as a ground. If you touch the positive terminal first and accidentally drop a tool onto any metal part, it can cause a short circuit, sparking dangerously and potentially damaging the computer or audio system. Key steps: First, ensure the engine is off and the key is removed. Use a wrench to loosen the negative clamp and move it away. Then, handle the positive terminal. When reinstalling the battery after repairs, reverse the order—connect the positive first, then the negative. Remember, this small detail can prevent major issues. I always follow this routine, making it a habit for worry-free safety.
