How to jump-start a car

by John Goepel

You jump-start a car by attaching the weak battery to a similar but strong battery with cables specially made for the job. It's important to follow the exact order of procedure to do this safely:

  1. Locate the battery. It has two terminals, each marked with a symbol: - for the negative and + for the positive. In some cars, the battery is difficult to reach, so there is often a more accessible remote positive terminal in the engine compartment.
    If you can't access the terminals -- or even find the batter -- consult the owner's manual.

  2. The good battery must be similar to the one in the car that won't start. Most gasoline-powered cars have 12-volt systems; older cars may have six-volt systems. Park the car with the good battery close enough for the cables to reach the car needing a start, but not so close that they touch.

  3. Turn off the ignition and all accessories on both cars; set parking brakes; put transmissions in park (automatic) or neutral (manual).
  4. Connect the cables in this order:

    1. Connect one cable to the positive terminal of the weak battery.
    2. Connect that cable's other end to the positive terminal of the good battery.
    3. Connect another cable to the negative terminal of the good battery.
    4. Connect the other end of that cable to a ground on the car that won't start.

      5. Check the owner's manual to see if there's a special ground terminal under the hood.
      Otherwise, the engine block is a good ground. Do not attach the cable to the negative terminal of the faulty battery.
  5. Start the engine of the car with the good battery and let it idle.
  6. Start the car with the bad battery.
  7. After you get the jumped car going, disconnect the negative cable from its ground connection, then from the terminal on the good battery. Next, disconnect the positive cable from both batteries. If the charging system warning lamp stays lit and the engine dies, another jump-start won't help. If the light goes out, there's a good chance the battery will recharge as you drive.