How to Jump-Start a Car
A dead battery is the most common breakdown there is — and jumping a car is simple once you know the correct order. Getting the connections right prevents sparks, damage, and injury.
- Connect red to positive, black to negative — in the right order.
- Connect the final black clamp to bare metal, not the battery.
- Start the working car, then the dead car.
- Disconnect in reverse order once the dead car is running.
Gather your supplies
You'll need a set of jumper cables or a portable jump starter. If you're using cables, you'll also need a second car with a good battery. Park the two cars close enough that the cables reach, but make sure they're not touching. Turn off both ignitions before you connect anything.
Identify the terminals
Open both hoods and find the batteries. Each has a positive terminal, marked with a plus sign and usually red, and a negative terminal, marked with a minus sign and usually black. If the terminals are dirty or corroded, wipe them clean before connecting. Getting these right is the key to a safe jump.
Connect the red clamp first
Connect one red clamp to the positive terminal of the dead battery. Then connect the other red clamp to the positive terminal of the good battery. Red goes to positive on both ends — always. Making the red connections first, and the black connections second, is what keeps sparks away from the battery.
Connect the black clamps
Connect one black clamp to the negative terminal of the good battery. Then connect the other black clamp to a bare metal surface on the dead car — an unpainted bolt or bracket on the engine is ideal. This completes the circuit safely, away from the battery.
Start the working car
Start the car with the good battery and let it run for a couple of minutes. This sends a charge into the dead battery. Then try starting the dead car. If it starts, leave both cars running. If it doesn't, wait a few more minutes and try again.
Disconnect in reverse order
Once the dead car is running, disconnect the cables in the reverse order: remove the black clamp from the dead car's metal first, then the black from the good battery, then the red from the good battery, then the red from the dead battery. Don't let the clamps touch each other while any are still connected.
Let the car run
After jumping, drive the car for at least twenty to thirty minutes so the alternator can recharge the battery. If the battery dies again soon after, it may need replacing, or the charging system may have a problem. A jump starts the car — it doesn't fix the underlying issue.
Use a portable jump starter
A portable jump starter is a small battery pack that jumps your car without another vehicle. It's safer and easier than cables, and it means you don't need a stranger's help. Many also charge phones and have a flashlight. They're a great addition to any emergency kit.
Know when to call for help
If you're unsure about the process, the battery looks damaged or leaking, or you're in an unsafe location, call roadside assistance instead. A damaged battery can be dangerous to jump. Knowing when to let a professional handle it is part of doing it safely.
Keep the cables untangled and inspected
Before you ever need them, check that your jumper cables are in good shape — no frayed insulation, no corroded clamps — and keep them coiled neatly so they're ready to use. Damaged cables are a safety hazard, so replace them if they show wear.
Storing them in an easy-to-reach spot means a dead battery is a ten-minute inconvenience instead of a stressful search. Good tools, ready to go, make all the difference.
Frequently asked questions
What order do I connect jumper cables?
Red to the dead battery's positive, red to the good battery's positive, black to the good battery's negative, then black to bare metal on the dead car. Disconnect in reverse.
Can I jump-start a car by myself?
Yes, with a portable jump starter. It connects the same way but provides the power itself, so you don't need another vehicle.
Is it safe to jump-start a modern car?
Yes, if you connect the cables correctly. Modern cars have sensitive electronics, which is why the correct connection order — and the final clamp on bare metal — matters.