Short answer
Park the good car close, both engines off. Clamp red to the dead battery’s plus (+), then red to the good battery’s plus. Clamp black to the good battery’s minus (−), and the last black clamp to bare metal on the dead car’s engine, away from the battery. Start the good car, wait 3 to 5 minutes, then start yours. Remove the clamps in reverse order.
Safety first
Do not jump-start on a highway shoulder: turn on your hazard lights, stay away from traffic and call roadside assistance. Never jump a battery that is cracked, leaking or frozen. Keep sparks and flames away from the batteries, and never let the clamps touch each other.
How to connect jumper cables in the right order
1Park close, engines off, hoods up
The cars should not touch. Turn both engines off, set the parking brakes and find the plus (+) and minus (−) on each battery.
Read all the steps
- Park close, engines off, hoods up. The cars should not touch. Turn both engines off, set the parking brakes and find the plus (+) and minus (−) on each battery.
- Red clamp on the dead battery’s plus (+). Clamp one red end to the plus post of the dead battery. Keep the other three clamps apart so they never touch.
- Other red clamp on the good battery’s plus. Clamp the other red end to the plus post of the good battery, in the helper car.
- Black clamp on the good battery’s minus (−). Clamp one black end to the minus post of the good battery.
- Last black clamp on bare metal. Clamp it to an unpainted bolt or bracket on the dead car’s engine, away from the battery. Any spark then happens far from the battery.
- Start the good car, wait, then start yours. Let it run 3 to 5 minutes, then start your car. Remove the clamps in reverse order: black from the metal first, red from the dead battery last.
- Still not fixed? Call a mechanic Especially if: it still will not start after two or three tries.
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With a portable jump starter
- 1
Make sure the jump starter is charged and switched off.
- 2
Clamp red to the plus (+) post of the dead battery.
- 3
Clamp black to bare metal on the engine, away from the battery, unless the jump starter’s manual says otherwise.
- 4
Turn the jump starter on and start the car. Then turn it off and remove black first, then red.
What not to do
- Do not let the clamps touch each other once any clamp is connected.
- Do not put the last black clamp on the dead battery’s minus post. A battery can give off hydrogen gas, and the last clamp often sparks.
- Do not jump a battery that is cracked, leaking, bulging or frozen.
- Do not lean over the batteries while the cars start.
When to call a mechanic
- It still will not start after two or three tries.
- The battery is cracked, leaking, swollen or hissing.
- The car dies again soon after the jump (likely the alternator).
- You are stuck on a highway shoulder or in traffic.
Frequently asked questions
What order do you connect jumper cables?
Red to the dead battery’s plus, then red to the good battery’s plus. Black goes on the good battery’s minus, and the last black clamp on bare metal on the dead car, away from the battery. Remove them in reverse order.
Why does the last clamp go on metal and not on the battery?
Because the last connection can make a small spark. A battery can give off hydrogen gas, so the spark should happen away from it, on bare metal on the engine.
How long do I wait before starting the dead car?
Let the good car run for about 3 to 5 minutes with the cables connected, then try. If it does not start after a few tries, stop and call for help.
How long should I run my car after a jump-start?
Drive at least 30 minutes so the alternator recharges the battery. Then have the battery and charging system tested.
Can you jump-start a car in the rain?
Yes, with care. Keep the clamps out of puddles, dry your hands and make sure the clamps never touch each other.
Can jump-starting damage my car?
Done in the right order, it is very unlikely. Reversed cables or touching clamps can damage the battery or the electronics, so check plus and minus twice before you clamp.