How to Jump Start a Car Battery

Car Engine and Jumper Cables
What You'll Need
Charged car battery
Jumper cables
Protective eye gear
Screwdriver with insulated handle
Steel wool or fine-grit sandpaper

Anyone who has driven a car for any significant length of time has felt the frustration of trying to start a car with a dead car battery. Here are five steps you can take to jump start your car next time you find it with a dead car battery.

Step 1 - Prepare to Charge Your Battery

Before attempting to jump your battery, it is important you protect yourself and your car's electrical system. To protect yourself, be sure to wear heavy, dry gloves and safety glasses that will protect your eyes from possible flying sparks. If you'll be connecting your car's battery to another one in a car, be sure all electrical components on both cars are turned off or unplugged. When carrying any car battery be careful to avoid letting it come in contact with your clothes or skin, since the battery is filled with sulfuric acid.

Step 2 - Check Your Battery for Corrosion

car battery

Examine your battery. Look at the base of the battery's two terminals where the cables are connected to the terminals. If you see greenish material that looks like dried foam on or near the terminal, this is an indication that the surfaces of your terminal and cable clamp where it fits over your terminal have become corroded. This corrosion can create electrical insulation between the battery terminal and the battery cable. Often, you'll find that even without visible corrosion, one or both of the terminals are corroded.

Step 3 - Clean Your Battery Terminals

To clean corrosion off your battery terminals and cable clamps, use your wrench to loosen the cable clamp that covers the vertical surfaces of your terminals. When the clamps have been loosened, remove the cable from one of the terminals. Leave the second cable on its terminal, so you can avoid touching these cables together.

Use steel wool, a steel brush or sandpaper to clean off the surfaces of your cable clamp and terminal. Attach the cable to its terminal and tighten the bolt on the cable clamp. Repeat this step with the other terminal and cable.

Step 4 - Connect the Two Batteries

one car connected to another with jumper cables

Place your car within reaching distance of the battery that will be supplying power to your dead battery. Locate the positive (+) terminal on your dead battery and clamp the red cable end to it. Clamp the positive cable end to the positive terminal on the booster battery. Clamp the black cable end to the negative terminal of the dead battery, and clamp the far end of the black cable to an engine nut of the booster car.

Step 5 - Start the Car with the Dead Battery

Turn the ignition key of the car with the dead battery. When the car is running, disconnect the battery cables, being careful not to let the cable ends touch each other. Allow your car to run at least an hour to charge the battery before turning it off.