How to Jump-Start a Car, Step by Step

By ShoulderCrew · Updated October 27, 2026 · Denver, Colorado

A dead battery is the most common reason a car will not start, and it is one of the easiest roadside problems to fix yourself if you do it in the right order. Here is the safe way, plus the situations where you should not try.

What you need

• A set of jumper cables (at least 10 to 12 feet, heavier gauge is better) or a portable jump pack.
• A second car with a healthy battery, if you use cables.
• Your owner's manual, because a few cars have special jump points.

Jumping with cables: the order matters

1. Park the cars close, not touching. Turn both off, set parking brakes, and take the keys out of the ignition on the helping car only after it is parked.
2. Turn off everything in the dead car: lights, radio, heater, charger cables.
3. Red clamp to the dead battery's positive (+) terminal.
4. Other red clamp to the good battery's positive (+) terminal.
5. Black clamp to the good battery's negative (−) terminal.
6. Last black clamp to bare, unpainted metal on the dead car, such as a bolt on the engine block or the frame, away from the battery. This final connection can spark, which is why it goes away from the battery and not on the dead battery's negative post.
7. Start the good car and let it run for a few minutes so it can send charge to the dead battery.
8. Try the dead car. If it does not start in a few tries, wait a couple more minutes with the good car running, then try again. If it still will not start, the problem may not be the battery.
9. Remove the cables in exact reverse order: the black clamp from the metal ground first, then the black from the good battery, the red from the good battery, and the red from the formerly dead battery. Do not let the clamps touch each other while they are still attached to a battery.

Using a portable jump pack

A jump pack is easier and does not need a second car. Connect red to positive and black to negative or a bare metal ground (follow the pack's instructions, since designs differ), turn the pack on, start the car, then disconnect. A pack you keep charged in the trunk is one of the cheapest ways to avoid a long wait.

When a jump will not work

• Clicking, then nothing, even after several minutes of charging: the battery may be too far gone, or the terminals may be corroded. Cleaning loose, crusty terminals sometimes fixes it.
• It starts, then dies as soon as the cables come off: that points to the alternator, not the battery.
• Lights are bright but the engine will not crank: that is usually a starter or other problem, not a dead battery.
• Hybrids and EVs: they have a small 12-volt battery that runs the electronics. Use only the jump points your manual shows, and never connect to the high-voltage system.
• Frozen or damaged battery: do not try to jump a battery that is swollen, cracked or frozen.

After the jump

Keep the car running and drive it for a while so the alternator can recharge the battery. We cover how long in how long to run your car after a jump start. If the battery is more than three or four years old, get it tested, because a battery that died once will often die again.

Colorado tip: cold and altitude

Cold is the real battery killer along the Front Range. A battery that is marginal in September can fail on the first 10°F morning. If your car is slow to crank on cold mornings, test the battery before winter, not after. More in our guide to why a car will not start in cold weather.