How to Jump Start a Car Battery

It's easy to jump start a car battery, but you'll want to make sure you pay close attention to the safety requirements before you tackle this job. A wrong connection can cause serious damage to your car battery or to you. Follow these directions carefully for a safe and effective jump start of your car battery.

Line up the Vehicles
You'll want to get the two engines as close as possible so the jumper cables can reach both car batteries. Make sure the cars aren't touching.

Turn Everything off
Turn off the engines of both cars. For the car that needs the jump, turn off the air conditioning or the heat, the fan, the radio, blinkers or emergency flashers and anything else that uses power. Unplug cell phones, MP3 players and CD players.

Check the Battery
Is the battery cracked or warped? Stop right there. You'll need to buy and install a new battery instead of trying to use the cracked or deformed battery. Never try to charge a battery that is leaking or damaged; it could explode.

Clean Off Excess Corrosion
If you see excess corrosion on the terminals, use a solution of one tablespoon baking soda to one cup of water and a nylon bristle brush to remove corrosion. In a pinch, you can use a piece of sandpaper to lightly scrub off corrosion. Wear safety goggles while you do this, and wash your hands immediately after removing the corrosion. Wear gloves if you have them; even the dry material can cause burns.

Connect the Jumper Cables to the Dead Car First
Follow these instructions very carefully, making sure to connect the cables in this exact order.

  1. Connect the positive cable to the positive post of the car battery of the dead car. This should be red to red.
  2. Connect the positive cable to the positive post of the car battery on the live car. Again, this should be red to red.
  3. Connect the negative cable to the negative post of the car battery of the live car. This should be black to black.
  4. Connect the negative cable to a clean, solid, unpainted metal part of the engine of the dead car. Look for a large, shiny, clean metal nut in the engine and make sure the connection is secure. You will get a spark when you make this connection, so be prepared. Do not connect the negative cable to the dead battery itself. The spark can cause an explosion.

Charge the Dead Battery
Start the engine of the live vehicle and allow it to run for a few minutes, charging the dead battery. Make sure the headlights and extra accessories of the live vehicle are turned off, so the live car is not drained of too much energy.

Start the Dead Car
While the connection is still intact, try to start the dead car. If the car does not start, wait a few more minutes and try again.

Remove the Cables
Disconnect the cables in the following order:

  1. Remove the negative cable from the unpainted metal piece in the car that was jumped. This should effectively break the energy circuit. Be careful when doing this. Don't touch the positive cable or the metal surface, or you could get a shock.
  2. Remove the negative cable from the negative post of the live vehicle that provided the charge.
  3. Remove the positive cable from the positive post of the vehicle that provided the charge.
  4. Remove the positive cable from the positive post of the battery you've just charged.
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