When jump-starting a car, you must always connect the positive (red) cable to the dead battery's positive terminal first. This initial connection is the safest starting point. The correct and safe order for all connections is: 1) Red to dead, 2) Red to donor, 3) Black to donor, and 4) Black to an unpainted metal surface on the dead car's engine block or frame.
The reason for this specific sequence is to minimize the risk of a spark occurring near the battery, which could potentially ignite hydrogen gas emitted from the battery cells. By connecting the positive cable to the dead battery first, you are establishing the circuit's path away from the most likely source of danger. The final connection—the black negative cable to a grounding point on the car's chassis instead of the dead battery's negative terminal—ensures that any final spark occurs far from the battery itself.
Here is a quick reference table for the correct procedure:
| Step | Cable Color | Connection Point | Key Reason |
|---|
| 1 | Red (+) | Dead Battery's Positive Terminal | Establishes circuit safely |
| 2 | Red (+) | Donor Battery's Positive Terminal | Completes the positive circuit |
| 3 | Black (-) | Donor Battery's Negative Terminal | Connects the negative side |
| 4 | Black (-) | Unpainted Metal on Dead Car's Engine | Grounds the circuit, avoiding a spark near the battery |
After the cables are securely connected, start the donor car and let it run for a few minutes. Then, attempt to start the dead car. Once it's running, carefully disconnect the cables in the exact reverse order: black from the ground on the previously dead car, black from the donor car, red from the donor car, and finally, red from the now-running car. Let the jumped car run for at least 20 minutes to allow the alternator to recharge the battery.
