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Jump Starting a Vehicle

Lesson Progress

Jump Starting a Vehicle

Safety Precautions

  • Be sure all electrical equipment is off. If you connect the jumper battery while a load is being drawn, a spark could occur.
  • Check the battery-fluid level. If the plates are exposed, add water until they are covered. Never add acid.
  • Make sure both batteries are of the same voltage.
  • Make sure vent caps are in place to prevent electrolyte splash.
  • Use good quality jumper cables.

Jump Starting

Before connecting the jumper cables, be certain of the battery polarity:

  • Connect the first cable (red) to the positive (+) terminal of the good battery and then attach the other end of that (red) cable to the positive (+) terminal of the dead battery,
  • Next, attach the second cable (black) to the negative (-) terminal of the good battery,
  • Attach the fourth and final connector (black) to a clean metal part, such as the engine block of the vehicle being energized, rather than to its negative battery terminal*.
  • Never lay your tools on top of the battery as they could come in contact with both posts, or the positive post and a ground, creating a short,
  • Start the engine of the good vehicle and increase the engine to a fast idle for about one minute,
  • Start the engine of the dead vehicle,
  • Once started stop the engine of the good vehicle and turn off the ignition,
  • Leave the engine of the jumped vehicle running, 
  • Disconnect the jumper cables using the reverse procedure from above**.

*NOTE: This method completes the electrical circuit as if it were connected to the dead battery, however any sparks that are produced are kept away from explosive battery gases.

**CAUTION: DO NOT allow the exposed metal parts of the jumper leads to touch each other or other metal parts of either vehicle until all leads have been safely disconnected.