Should You Connect the Positive or Negative Terminal First When Jump-Starting a Car?
4 Answers
When jump-starting a car, you should first connect the positive terminals of both batteries. Below is additional information on jump-starting: 1. Specific Procedure: First, connect the positive terminals of both batteries, then connect the negative terminals. After the engine starts, disconnect the negative terminal first, followed by the positive terminal. 2. Reason for Connecting the Positive Terminal First: If you connect the negative terminal first and then the positive terminal, connecting the negative terminal will not cause any issues. Similarly, connecting the positive terminal to the first car will not pose a problem. However, when connecting the positive terminal to the second car, if the battery clamp accidentally touches the car body, it can cause a short circuit in the first car. This short circuit may damage various electronic control modules in the car, potentially rendering the battery useless and posing significant danger.
Last time my car battery died, I also thought about this issue. The standard procedure is to connect the positive terminal first: take out the jumper cables, attach the red clamp to the dead battery's positive terminal, then to the rescue car's positive terminal; next, use the black clamp to attach to the rescue car's negative terminal, and finally connect the other end of the black clamp to the dead car's engine block or another clean metal part of the body—never directly to the battery's negative terminal to avoid spark risks. There might be hydrogen gas leakage inside the battery, and sparks could cause an explosion, so safety is key. I usually recommend keeping a good-quality set of jumper cables in the trunk, so if this happens, you can handle it with help. Afterward, disconnect in reverse order: first remove the black body clamp, then the rescue car's negative clamp, and finally the red clamp. Regularly checking the battery can reduce the need for jump-starts and save trouble.
I've been driving for half my life and have lost count of the number of jump starts I've done. At first, I made mistakes too—connecting directly to the negative terminal caused sparks to crackle, which gave me a scare. Later, I learned the correct sequence: first, clamp the red jumper cable onto the dead battery's positive terminal, then attach the other end to the live car's positive terminal. Next, clamp the black cable to the live car's negative terminal, and finally, attach the other end of the black cable to a bare metal part of the dead car's frame, avoiding any spark contact near the battery. This method has worked flawlessly almost every time. After completing the connection, don’t rush to remove the cables—let the live car’s engine run for a few minutes to charge the dead battery before disconnecting. Opt for thicker copper-core jumper cables for better performance. When heading out on long trips, nothing annoys me more than a dead battery, so I often teach newcomers to check the voltage in advance.
Jump-starting is quite straightforward; just follow the steps in order. First, attach the red clamp to the positive terminal of the dead battery, then to the positive terminal of the rescue vehicle. Next, connect the black clamp to the negative terminal of the rescue vehicle, and finally, attach the other end of the black clamp to an unpainted metal part of the dead car's chassis, such as the engine bracket. Avoid touching the battery's negative terminal to prevent sparks. Once connected, start the engine of the rescue vehicle, then attempt to start the dead car. To disconnect, reverse the order: first remove the black clamp from the chassis, then the negative clamp from the rescue vehicle, and finally the red clamps. The whole process takes just a few seconds. Remember this rhyme for convenience: red to both positives, black to one negative and ground. Keep a set of jumper cables in your car for emergencies—safe and reliable.
