How to Jump Start a Car Battery

How to Jump Start a Car

A car battery failure is probably one of the worst things that can happen on the road. Whether it’s because you left your headlights on, a charging system failure, or exposure to extreme temperatures — knowing how to properly jumpstart a car is a valuable skill you need. 

Jumpstarting a car involves utilizing jumper cables to connect a dead battery to a functional one in another vehicle, which allows for the transfer of power to revive the stalled engine. 

With this essential technique, you can effectively handle battery emergencies, and even aid fellow motorists. This guide will walk you through the step-by-step process of jumpstarting a car safely, while highlighting precautions and tips.

How to Jump Start a Car with Dead Battery

Jump-starting a car, also known as a boost, is a process of using jumper cables to connect a dead battery to a working battery in another vehicle. Below, we provide steps on how to jump start a car safely. 

Note: Before attempting to jump-start a car, always refer to your vehicle’s owner’s manual for specific instructions and safety precautions. Additionally, ensure both vehicles have the same voltage (usually 12 volts) and are parked close enough for the jumper cables to reach each other without touching.

Here are the materials you’ll need:

  • Jumper cables: Also known as booster cables, these insulated wires have clamps on each end, typically color-coded red and black. They are used to connect the two car batteries together. Make sure to follow the correct order. 
  • A working vehicle with fully charged battery: You’ll need another vehicle with a fully charged battery to provide the power to jump-start the dead battery. Do not use an electric or hybrid car for the second vehicle. 
  • Safety gear: Although not essential, it’s a good idea to have safety gear on hand, such as safety gloves and safety glasses, to protect yourself from any potential sparks or accidental contact. Remove any rings you’re wearing. 

1. Prepare the vehicles

Park the working car (the “donor” car) close to the dead car so that the jumper cables can reach both batteries easily. Both cars can be positioned next to each other or may face one another. Turn off the ignition and all electrical components in both vehicles (lights, radio, A/C, etc.). Engage the parking brakes on both cars. 

2. Identify battery terminals

Pop open the hoods of both cars. Identify the positive (+) and negative (-) terminals on both car batteries. They are usually marked with a (+) and (-) sign or are color-coded (positive is red, negative is black).

3. Attach the jumper cables

Take the jumper cables and unfold them, making sure the clamps do not touch each other. Start by connecting the red (positive) clamp to the positive terminal of the dead battery. (RED to DEAD) 

4. Connect the second red clamp

Connect the other red (positive) clamp to the positive terminal of the working battery in the other vehicle. (RED to DONOR)

5. Connect the black clamp

Connect the black (negative) clamp to the negative terminal of the working battery. (BLACK to DONOR) 

6. Ground the circuit

For the final connection, attach the other black (negative) clamp to an unpainted metal surface on the dead car’s engine block. This will help ground the circuit and minimize sparks near the battery. (BLACK to METAL)

7. Start the working car

Start the engine of the working car and allow it to operate for a few minutes. This will allow the charging system to supply power to the dead battery.

8. Attempt to start the dead car

Now, try starting the engine of the car with the dead battery. It should turn over and start. If it doesn’t start, inspect the connections and make another attempt. If it still doesn’t start, other issues may be affecting the vehicle.

9. Remove the jumper cables

Once the dead car starts, let both vehicles run for a few minutes to allow the charged battery to transfer some power to the previously dead battery. Then, carefully disconnect the jumper cables in the reverse order you connected them:

  1. Remove the black (negative) clamp from the engine block of the formerly dead car.
  2. Remove the black (negative) clamp from the negative terminal of the working battery.
  3. Remove the red (positive) clamp from the positive terminal of the working battery.
  4. Remove the red (positive) clamp from the positive terminal of the formerly dead battery.

10. Keep the engine running

Drive the vehicle that was jump-started for at least 15-20 minutes to recharge its battery. This will help ensure the battery retains enough charge for the next start.

Remember to drive cautiously after jump-starting your car. Also, have the battery and charging system checked by a professional to prevent future problems.

Tips After Jumping a Car with Dead Battery

Consider the following tips to ensure a smooth and safe continuation of your journey after the jump has been completed:

  • Avoid turning off the engine: If possible, avoid turning off the engine immediately after jump-starting the car. In case you need to make a quick stop, try to keep the engine running, as restarting a car that has just been jumpstarted may require another jump.
  • Get the battery checked: As soon as possible, have the battery and charging system checked by a professional mechanic. A dead battery might indicate an underlying issue that needs to be addressed to prevent future problems.
  • Check for dashboard warning lights: After jump-starting, pay attention to the dashboard warning lights. If any new warning lights — such as orange or yellow lights — come on or if the battery light remains illuminated, have the vehicle checked by a professional.
  • Replace your battery: If the battery doesn’t hold a charge or cannot be jump-started, it might be because it’s old and need to be replaced. Heat or cold damage is another reason. A professional can help you determine what to do next. 


During moments of unexpected battery failure, jumpstarting a car allows you to get back on the road and see a mechanic. Follow the outlined steps above and remember to adhere to safety guidelines. More importantly, you need to check the owner’s manual. Otherwise, call a professional. In that case, contact Neighborhood Roadside Assistance for expert assistance. We can help you in New Jersey, New York, and Atlanta!