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Jump-start a car

A flat battery can often be started from another car with jumper cables. The order you connect the cables matters, and your owner’s manual has the final say for your car.

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Last reviewed against 1 official source.

Who this is for

Drivers of cars with a regular 12-volt battery who have cables and a second car. Hybrids and electric vehicles have their own instructions: use only the manual.

How do I jump-start a car safely?

Only when you need it. If a car needs jump-starting often, the battery and charging system should be inspected. The steps below follow one maker’s published manual as an example.

From: Mopar (Stellantis)

What you need

Tools

  • Jumper cables in good condition
  • A second vehicle with a healthy battery

Supplies

  • Your owner’s manual, open to the jump-starting page

Steps

  1. Read your manual’s jump-start pageIt shows where to connect on your car. Some cars have special posts away from the battery.
  2. Set up both carsPark them close enough for the cables to reach. Turn both off and set the parking brakes.
  3. Red clamp to the flat battery’s positive (+) postThis is the first connection.
  4. Other red clamp to the good battery’s positive (+) postPositive to positive.
  5. Black clamp to the good battery’s negative (−) postThis is the third connection.
  6. Last black clamp to bare metal on the stalled carUse an unpainted metal part of the engine or frame, away from the battery. Do not clamp it to the flat battery’s negative post.
  7. Start the helper car, then the stalled carLet the helper idle for a few minutes first. Once the stalled car runs, remove the clamps in the reverse order, starting with the bare-metal clamp.

Safety notes

  • The manual warns that a spark at the flat battery’s negative post could make the battery explode. That is why the last clamp goes on bare metal away from it.
  • Do not try to jump a battery that is cracked or leaking.
  • Keep the clamps from touching each other, and keep hands, hair and cables away from belts and fans.
  • The order in your own owner’s manual comes before this guide.

When to call a professional

  • You are unsure of any step, or the cables are damaged: call roadside assistance.
  • The car needs jump-starting again and again. Have the battery and charging system inspected.
  • Hybrid or electric vehicles, and any car showing an airbag or high-voltage warning.

Sources

This guide is general information written in our own words from the sources above. Your owner’s manual and the instructions for your own equipment come first.

Tell it once. It remembers.

General guidance: a yearly battery check makes a flat battery less likely.

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