Published 27 Jul 2026 · 4 min read
How to jump start a car safely: the correct cable order, step by step
Jump starting a car has a correct order with just four steps. The short rule: positives first, negatives last, and the final clamp goes on bare metal on the dead car, not on the dead battery's negative terminal. Done in that order, a jump start is far safer than most people fear.
Check these four things first
- Cable condition: intact insulation, firm clamps, and a gauge thick enough for a car
- Both engines off: switch off headlights, air-con, radio, and other electrics before connecting
- Never jump a damaged battery: a cracked case, leaking residue, a swollen shape, or heavily corroded terminals mean the battery needs replacing rather than jumping
- Start-Stop cars, hybrids, and EVs: open the owner's manual first, because many have dedicated jump points that are not the battery terminals
The correct cable order
- Clip the red cable to the positive (+) terminal of the dead battery
- Clip the other red end to the positive (+) terminal of the donor car's battery
- Clip the black cable to the negative (-) terminal of the donor car's battery
- Clip the final black end to bare metal on the dead car's engine block or chassis, away from the battery, never to the dead battery's negative terminal
Step 4 is pure safety. Attaching the last clamp can produce a small spark, and a battery under charge gives off flammable hydrogen gas. Moving that final connection to bare metal well away from the battery keeps the spark away from the gas.
Once everything is connected, run the donor car's engine for a few minutes, then try starting the dead car.
Disconnecting and what comes next
Disconnect in exactly the reverse order. The black clamp on bare metal comes off first, then work back to the red clamp on the once-dead battery, keeping the clamps from touching each other on the way.
Once the car is running, do not relax yet. A short drive cannot recharge a flat battery back to full, so have the battery and charging system tested soon. A battery that needs repeated jumps is telling you it needs replacing rather than another charge. At that point, our guide to choosing a cheap car battery without getting burned is the place to start before you buy.
Still not starting?
If the order was right and the car still will not start, the problem may be more than a flat battery: our battery vs alternator guide shows how to tell. And if you would rather not do this yourself, use our mobile battery replacement service in Korat: send the car's model and location, we confirm the battery and total price before any work, and you pay when the job is done.
Keep a set of jumper cables in the boot, and read the four steps again before you need them. If your battery has started needing jumps regularly, have it tested before it strands you.