Mechanics

Battery Jump Start

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Step by step instructions on how to jump start an automotive battery. This article pertains to all vehicles.

Difficulty Scale: 2 of 10

Tool and Supplies Needed

  • Battery jumper cables.
  • Protective eyewear and gloves
  • Flashlight

Park the vehicle or place a charged battery that will be used as the jumper near the front of the car that is going to be jumped started, engine "OFF". (CAUTION: Never connect positive and negative terminals with a conductive object such as a wrench. Also, never connect the positive battery terminal to any body, chassis or engine parts or allow jumper cable ends to connect to each other or the vehicle body or engine at any time.)

Step 1 - Locate the negative battery terminal on the charged and dead battery. These terminals are smaller in diameter than the positive terminals and should have a (-) annotation.


Negative Battery Terminal

Step 2 - Locate and remove the positive battery terminal cover to identify the positive terminal on both dead and charged batteries annotated by a (+)


Positive Battery Terminal

Step 3 - A charged or new battery is needed to connect the jumper cables to. This can also be done with an additional vehicle which is more effective due to the additional alternator contributing to the voltage/amperage needed (engine running.)


Dead and Charged Battery

Step 4 - Connect the red jumper cable connector on the positive (+ red) side of the battery of the car that has the dead battery. Once the jumper cable end is attached slightly wiggle the jumper connector back and forth to insure a good electrical connection. Repeat this action for the charged battery.

Step 5 - Then, attach the black connector of the jumper cables to the negative (- black) terminal of the dead battery. Next, attach the remaining black jumper cable connector to an engine accessory bracket or any good ground of the charged vehicle. (Note: Keep cables clear from rotating engine parts.) The last connection is made at a good engine ground to avoid sparks at the battery. Sparks on or near the battery can cause the battery to explode. While explosions are rare they will more likely occur to a battery that is low on charge or a battery that has just been charged this is why the final circuit connection is at an engine ground source.

Step 6 - After the cable are successfully installed stand back from both hood areas of both vehicles. If a jumper battery is being used, turn the key to start the vehicle of the dead battery. If a vehicle is being used start the engine of the jumper vehicle (charged battery) and allow to idle for about 3 minutes. Then, manually increase the engine speed to about 1500 RPM for about 2 minutes. This will supply a charge for the dead battery.

Step 7 - Next, crank over the car's engine with the dead battery, it should crank over and start. Once the engine has started manually increase the engine speed to about 1500 RPM and hold for about 2 minutes.

Step 8 - Turn off the engine of the jumper vehicle and remove the black jumper cable end. Then, carefully remove the black and red jumper cables from the dead battery.

Step 9 - Next, remove the red jumper cable connector from the jumper car and close the hood on both vehicles.


Once the job is complete inspect the battery light on the instrument cluster, if illuminated the charging system has a problem. If repeated jump starts are required and the charging system has checks out okay, the battery has failed to hold a charge, or there is an electrical draw in the system. If this procedure fails and the vehicle still has not started, the battery could have failed (shorted) internally and cannot be jump started. A failed battery connection could also cause the engine not to start.


Helpful Information

Low battery voltage is a common car problem. As a battery ages it can lose the ability to store electricity resulting in an insufficient flow of electrical energy to the starter. The starter is designed to operate on a high amperage 12 volt system, when a starter is subjected to low voltage or amperage (flow) it will cause the starter to not operate. While using a quality set of jumper cables a jump start is needed to troubleshoot the reason the battery is dead. Inexpensive cables do not work well because a higher gauge wire (smaller diameter) is used in their construction resulting in restricting current flow.

Best Practices

  • Never connect jumper cable ends to each other or allow the positive jumper cable end to connect body ground.
  • Allow the battery to fully charge once a jump start has been performed.
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AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-11-24)