How to Jump-Start a Car — Safely
The correct clamp order, why the last connection matters, and when to give up and call for service. Memorize this order: Red dead → Red donor → Black donor → Black ground.
Safety first: a dead battery can release small amounts of hydrogen gas, which is flammable. The correct connection order (below) ensures any spark happens away from the battery.
The connection order (memorize this)
- Red clamp → dead car's + terminal
- Red clamp → donor car's + terminal
- Black clamp → donor car's - terminal
- Black clamp → unpainted metal on the dead car (engine bolt, chassis ground), NOT the battery
To disconnect, do the reverse: black ground → black donor → red donor → red dead.
Step 1 — Park the donor car close enough
Position the donor close enough that the jumper cables reach both batteries — ideally front-to-front. Both cars in Park (neutral for manuals), engines off, parking brakes engaged.
Step 2 — Identify the battery terminals
Pop the hood on both cars. Identify the positive (+, usually a red cover) and negative (-, usually black) terminals on each battery. If the terminals are corroded (white or green crust), clean them gently with a wire brush before attaching cables.
Steps 3-6 — Connect the cables in order
Follow the numbered order above. Do not let the clamps touch each other or any metal while you're doing this — holding unclamped ends, keep them separated.
The reason the final connection is to unpainted metal (chassis ground) rather than the dead battery: that connection can spark, and you want any spark to happen away from the dead battery's potential hydrogen gas.
Step 7 — Start the donor car
Start the donor vehicle's engine and let it run for 2–3 minutes. This charges the dead battery and ensures the donor's alternator is supplying power.
Step 8 — Start the dead car
Try to start the dead car. If it cranks slowly, wait another 2–3 minutes with the donor running and try again. If after 5 minutes it still won't start, the battery is likely too far gone for a jump — call for service or replace the battery.
Step 9 — Remove the cables (reverse order)
Once the dead car is running, remove the cables in the reverse order you connected them: black on the jumped car (ground), black on donor, red on donor, red on formerly-dead battery. Again, keep clamps from touching each other or any metal while handling.
Step 10 — Drive the jumped car for at least 20 minutes
Drive the formerly-dead car for at least 20 minutes to let the alternator recharge the battery. Avoid short trips for the next few days. If the battery dies again within a day or two, it needs replacement.
When to use a portable jump pack instead
A lithium-ion jump pack ($60–$150) lets you self-jump without a donor car. Keep one in the trunk. They hold charge for months, work in cold weather, and eliminate the "who do I call at 6am?" problem. Good options: NOCO GB40 (budget), NOCO Boost Plus (reliable mid-range), Stanley J5C09 (includes compressor).
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