Mechanic using jumper cables to start a car

How to Jump-Start a Car

By the Mercury Team

With a little luck and following general car maintenance tips, you can go years without jump-starting your vehicle. Still, the unexpected can happen, leaving you on the side of the road or in a parking lot with a dead battery. If you don’t know how to jump-start a car or just need a refresher, this step-by-step guide can help you safely get back on the road.

Be Prepared with the Right Tools

Keep the following equipment in your vehicle at all times to ensure you can jump-start your car whenever needed:

  • Jumper cables — If possible, buy the longest jumper cables available to ensure the other vehicle can reach your car.
  • Mechanical gloves — Disposable gloves are fine, but if you want the most protection, opt for heavy-duty mechanical gloves.
  • Flashlight — You never know if your battery will die at night, so keep a flashlight in your car to prepare you for those situations.
  • Owner’s manual — Your owner’s manual should be located in your glove compartment.

You’ll also need to find someone with a functioning vehicle to help jump-start your car. If you’re uncomfortable asking a stranger for help, consider getting a portable jump starter — a battery pack designed to boost a dead car battery without the assistance of another vehicle.

Tips Before Jump-Starting Your Car

Keep the following tips in mind when jump-starting your car, so you can stay as safe as possible:

  • Read your owner’s manual first — Your car’s manufacturer may recommend not jump-starting your car due to sensitive electronic circuitry.
  • Never jump-start a frozen, cracked, corroded, or leaking battery — Jump-starting a battery with these conditions can cause serious damage to your vehicle. Call a tow truck instead.
  • Don’t let the hook-up clamps touch each other when in use — This could result in an electrical shock.

Jumper cables sitting on a table

How to Jump-Start a Car — Step-by-Step Instructions

Follow this step-by-step guide on how to jump a car with jumper cables.

1. Find Another Vehicle to Jump-Start Your Car

  • First, ask someone with a functioning vehicle for assistance. Once you get help, have the other driver park their vehicle in front of your car, so both front bumpers face each other. If this position is not feasible, park the other vehicle alongside your car.
  • Don’t let the vehicles touch, but ensure they’re close enough to each other that the jumper cables can reach each battery.

2. Prepare Each Vehicle For Jump-Starting

  • Before hooking the jumper cables up to each battery, you and the other driver need to do a few things. First, set the gear selector lever to park and engage the parking brake for each vehicle.
  • Next, ensure that every electrical device in each car is turned off or unplugged. This means the headlights, radio, fan, overhead lights, and chargers plugged into the electrical outlet. The good battery needs to send all the electricity it can to the dead battery without interference.
  • Lastly, take the keys out of the ignition.

3. Locate the Battery Terminals

  • Open the front hoods for both vehicles.
  • Find both batteries and locate the terminals for each one. The positive terminal will be marked with a plus sign (+), while the negative terminal will have a minus sign (-).
  • There may be coated covers over the terminals. If so, remove them before hooking up the jumper cables.

4. Hook Up the Jumper Cables

  • Locate your jumper cables and stretch them out.
  • Jumper cables are almost always color-coded. The red cable is for the positive terminal, while the black cable is for the negative terminal.
  • First, clamp the red cable onto the dead battery's positive terminal. Then, take the other end of the red cable and attach it to the good battery’s positive terminal.
  • Next, clamp the black cable onto the good battery's negative terminal.
  • Do not attach the other end of the black cable to the dead battery's negative terminal because it can cause electrical sparks.
  • Instead, find a grounding piece of unpainted metal — e.g., a bare bolt — and attach the black cable to that. Some vehicles provide a built-in grounding spot under the hood. Check your owner’s manual to see if your car offers this feature.
  • Ensure the cables are firmly connected to the terminals.

5. Jump-Start the Car

  • Once the cables are connected, have the driver with the good battery put their keys in the ignition, start it up, and let the car run for at least a few minutes. During this process, the good battery sends electricity to the dead battery.
  • After a few minutes have passed, get in your car, put your keys in the ignition, and start it. Leave both cars running.

6. Remove the Jumper Cables

  • Start with the car that has the dead battery first. Remove the black clamp from the grounding spot, then detach the red clamp from the positive terminal. Set the clamps on the ground and make sure they don’t touch each other.
  • Move on to the car with the good battery. Remove the black clamp from the negative terminal, then remove the red clamp from the positive terminal.
  • Once you remove all the clamps, you can roll up the jumper cables and stow them away.


Every driver should know how to jump-start a car. It’s also important to always prioritize safety, so refer to this guide whenever you’re in this situation. However, if you purchase car insurance from Mercury, you can take advantage of roadside service and have a professional help you get back on the road.

Contact us today for a fast, free quote!

Mercury Team

The Mercury Marketing Team is made up of professionals in the fields of Content Creation, Public Relations and Social Media. The team works together to deliver professionally written and researched content to provide information for consumers.

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