when jump starting a car which cable goes first

[OHope]

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.

[DiBrooklyn]

Red on dead first, every time. That’s the rule my dad drilled into me. You hook up the red clamp to the positive terminal on the dead battery. Then, the other red to the good battery. Next, black to the good battery’s negative. For the last black clamp, don’t put it on the dead battery—find a shiny, unpainted bolt on the engine block. That way, if there’s a spark, it’s away from the battery. Reverse the order when taking them off. It’s simple once you get the rhythm.

[MacThomas]

The priority is safety. Connecting the positive (red) cable to the discharged battery first significantly reduces the hazard of an explosion. Car batteries can release flammable hydrogen gas. A spark from the final connection could ignite it if that spark happens right at the battery terminal. By making the final connection to a grounded metal part of the chassis, you move that potential spark to a safe distance. This procedure is mandated by all major automotive safety organizations, including the AAA, for this critical reason.

[IsabelleDella]

Think of it as a "good neighbor" policy: you want to help the dead car without causing trouble. Start by giving the dead battery a hand—connect the red cable to its positive terminal. Then, connect the other red to the helper car’s positive. Attach the black cable to the helper’s negative terminal. For the last step, be a good neighbor and don’t connect the final black to the dead battery’s negative post. Instead, find a clean, unpainted metal spot under the hood of the dead car, like a bracket. This keeps everything safe and sound.

[BrodyRose]

From an electrical flow perspective, connecting the red cable to the dead battery's positive terminal first establishes the intended path for the current. The entire system is designed to be grounded to the car's chassis. By connecting the final black clamp to the chassis of the dead car, you are completing the circuit through the vehicle's normal grounding system, not directly through the battery. This is actually a more efficient and much safer way to jump-start a modern vehicle, as it protects sensitive electronics from voltage spikes that can occur if a spark happens at the battery terminal.