It’s an essential skill that any driver should have, but if you ask five people how to jump-start a car with a run-down battery, you could get five different answers. Here’s the right way to give a dead battery a boost.

Connect the Vehicles

Pop the hood of both vehicles. Remember, the red connector is positive, and the black connector is negative. The red clamp on one end connects through to the red clamp on the other; the cables never cross in the center.

Take care when connecting the two vehicles – when connecting one clamp, try not to let the other clamp dangle into the engine compartment or rattle around under the hood.

  • Firmly connect one red clamp to the positive (+) terminal on the car with the dead battery.
  • Connect the other red clamp to the positive (+) terminal on the car with the good battery.
  • Connect one black clamp to the negative (-) terminal on the car with the good battery.
  • Connect the other black clamp to an unpainted metal surface anywhere in the engine compartment of the car with the dead battery. This will ground the connection – even a bolt or crossbar will do.

Note

Make sure all of the connections are firm, and the clamps are tightly secured. Make sure your ground connector isn’t close to any moving parts. You don’t want the clamps rattling around or moving when you go to start one of the vehicles.

Start Your Engines

Start the one with the good battery. Starting the vehicles in this order will immediately start charging the car with the dead battery, so in most cases you don’t need to let the car with the good battery run with the dead car shut off. However, if the battery in the dead car has been dead for a long time, you may need to let the car with a good battery idle a bit to get some charge into the dead car’s battery.

Once the booster car is running, go ahead and start the dead car. It will likely start up right away, but if it doesn’t, stop trying, wait a few minutes, and then try again. If it still doesn’t start after two or three tries, stop trying – you don’t want to damage the starter. It’s possible that the battery simply won’t hold a charge, or there’s something else wrong with the vehicle.

Disconnect the Vehicles

If your dead vehicle does come back to life, leave it running and then slowly disconnect the cables in the reverse order as you connected them. This means disconnect the ground on the dead car first, and then the negative terminal on the good battery. Then disconnect the positive terminal on the good battery, and finally the positive terminal on the now jump-started car.

Note

Be very careful when doing this – you’re dealing with live cables. Only touch the protected clamp handles, and when you disconnect one end, don’t let it dangle into the engine or allow a positive and a negative clamp to touch each other.

Drive Away

With luck, you can bid your friend with the good battery farewell and drive your now jump-started vehicle to a safe location. You may need to jump-start the vehicle again the next time you turn it off, but a good 15 minutes of drive or idle time should be enough to get a good charge on your battery.

However, it’s important to note that if the battery is in really bad shape, you should get to a mechanic or an auto parts store with a certified battery charger and leave your battery connected for several hours. Your alternator will definitely charge the battery while you drive, but it’s not meant to provide a full charge.

Jump-Starters and Battery Kits

If you don’t want to go through the hassle of finding someone to help you jump-start your car, or have to deal with an auto club or roadside assistance, a jump-start kit may be a wise investment. Most are small enough to be carried in one hand and can slide into a corner of your trunk until they’re needed.

When your battery dies, just pull out the jump-start kit, and depending on the model you have, connect it directly to your vehicle’s battery or to a power outlet inside the car, and allow the battery to charge for 15 minutes or so before starting the vehicle. Many jump-starters will also show you the battery’s overall health, and will tell you when to start the car.

Just be sure to keep the jump-starter charged periodically, or else you’ll find yourself with a dead battery and a dead jump-starter.

If you do go this route, it can save you the headache of finding a Good Samaritan to help with your dead battery, but make sure to follow the instructions for a good, safe jump-start.