How to Jump Start a Car Battery

battery terminal clamp

Jump a battery the safe way

Continued improvements in vehicle battery durability, reliability, and cranking amps have significantly reduced drivers' need for a jump start. Vehicle headlights that turn themselves off have also reduced those dead battery moments. Sadly, that doesn't mean you'll never face a dead battery or encounter another driver who is (it might be why you're reading this right now!). That's why you should learn the proper and safe way to jump start. Here's what to do.

Vehicle System
Ignition, Charging, & Electrical Systems
Skill Level
Beginner

This is a good project for new DIYers

Time to Complete
10 minutes
  1. With both vehicles turned off, look at both batteries and identify the positive (+) terminal, marked with red. With space under the hood at a premium on newer vehicles, many will not have the battery where it's easily visible, but you should be able to easily spot the connection points for jumper cables anyway. On the vehicle with the dead battery, also identify an unpainted metal surface that isn't next to the battery.

  2. Connect one of the red positive (+) jumper cable clamps to the dead battery's red positive (+) post.

  3. Connect the other red positive (+) jumper cable clamp to the good battery's red positive (+) post.

  4. Warning

    Never let the positive and negative jumper cable clamps touch when the other ends of the cables are connected to a battery. Doing so will generate sparks.

  5. Connect the negative black (-) clamp on that same end of the jumper cables to the black negative (-) post of the good battery.

  6. Important! Connect the other negative black cable to the clean, unpainted metal surface under the disabled vehicle's hood. DO NOT connect to the negative post of the dead battery as an explosion could result.

  7. Start the good vehicle. Allow it to run for five minutes with the jumper cables connected then attempt to start the disabled vehicle. If the engine won't turn over, trying repositioning the negative jumper cable that's on the unpainted metal surface to achieve better contact. If it still won't turn over, you may need to race the donor vehicle's engine a little so the alternator delivers more amperage.

  8. Disconnect the jumper cables in the reverse order they were connected.

     

    Jumpstarter/Portable Power Units are becoming very popular and can be carried with the vehicle in case of battery failure. If another vehicle isn't available for the jump start, use one to jump start by connecting it to the dead battery following the steps above.

Last updated June 14, 2017

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