Which Car to Hook Up First with Jumper Cables

Connect the red positive clamp to the dead car’s positive terminal first, then to the donor car’s positive terminal; next, attach the black negative clamp to the donor car’s negative terminal and finish by clamping the remaining black lead to an unpainted metal ground on the dead car. This order minimizes sparks near the battery and protects vehicle electronics.

Why the Order Matters

Automakers and roadside-assistance organizations recommend connecting the positive lead to the dead battery first and making the final connection to a ground point on the dead vehicle. Batteries can emit hydrogen gas; a spark near the battery can ignite it. Grounding away from the battery reduces that risk, and the sequence also helps protect sensitive electronics in modern cars.

Step-by-Step: Safe Connection Order

The following sequence details how to attach jumper cables correctly to reduce risk and improve the chances of a successful jump-start.

1. Turn both vehicles off, set parking brakes, and ensure they are in Park (automatic) or Neutral (manual). Switch off accessories and lights.
2. Identify the batteries or designated jump-start posts (often under the hood; check the owner’s manual).
3. Attach the red (positive) clamp to the dead car’s positive (+) terminal or jump-start post.
4. Attach the other red (positive) clamp to the donor car’s positive (+) terminal.
5. Attach the black (negative) clamp to the donor car’s negative (–) terminal.
6. Attach the remaining black (negative) clamp to a solid, unpainted metal point on the dead car (engine block or chassis ground), away from the battery and moving parts.

Following this sequence places the first and last connections away from high-risk points, reducing the chance of sparks near battery gases and helping safeguard electronics.

Starting and Removing the Cables

Once the cables are connected, bring the dead battery back to life carefully and remove the leads in reverse to avoid surges.

1. Start the donor car and let it run for 2–5 minutes to send charge to the dead battery.
2. Try starting the dead car. If it doesn’t start, wait another few minutes and try again. Avoid cranking for more than 10 seconds at a time.
3. After the dead car starts, let both vehicles idle connected for a minute.
4. Remove the cables in reverse order: black clamp from the dead car’s ground, black from donor negative terminal, red from donor positive, and finally red from the dead car’s positive.
5. Keep the revived car running for at least 20–30 minutes (preferably by driving) to allow the alternator to recharge the battery.

Reversing the removal order helps prevent accidental short circuits and voltage spikes when the systems are re-stabilizing after the jump.

Common Mistakes and Safety Tips

These frequent errors can damage vehicles or create hazards; avoiding them improves safety and success rates.

• Connecting the final black clamp to the dead battery’s negative post (risk of sparks near hydrogen gas).
• Reversing polarity (red to negative or black to positive), which can fry electronics or blow fuses.
• Letting clamps touch each other or metal while connected.
• Jump-starting a visibly damaged, leaking, or swollen battery.
• Using cables too thin for the task; heavy-gauge cables conduct better and stay cooler.
• Ignoring the owner’s manual jump-start points and procedures.
• Attempting to jump incompatible systems (e.g., 12V to 24V trucks).

By double-checking polarity, using proper grounds, and following vehicle-specific guidance, you greatly reduce risk of injury and electrical damage.

Special Cases to Consider

Some vehicles require extra care or a different approach when jump-starting due to their electrical systems.

• Hybrids and EVs: Do not attempt to jump-start the high-voltage system; many allow jump-starting only the 12V system via designated posts. Some EVs should not be used as donor vehicles—check the manual.
• Start-stop/modern luxury cars: Use the specified jump posts; batteries may be in the trunk or under seats, with sensors attached.
• Diesel or 24V systems: Use correct-voltage sources and follow manufacturer procedures.
• Frozen batteries: If the battery is frozen (common in extreme cold), do not jump; thaw safely first to avoid explosion risk.
• Portable jump starters: Follow the device’s instructions; connection order generally mirrors the procedure above.

When in doubt, consult the owner’s manual or call roadside assistance; specialized systems can be damaged by incorrect procedures.

Summary

Hook up the dead car first: red to the dead battery’s positive, red to donor positive, black to donor negative, and the final black to a solid ground on the dead car. Start the donor, then the dead car, and remove cables in reverse. This sequence minimizes sparks, protects electronics, and aligns with widely recommended safety practices.

Do I connect black or red first?

When connecting jumper cables to a car with a dead battery, always connect the red/positive cable first to the positive (+) terminal of the dead battery, and then to the positive terminal of the working battery. The negative (black) cables should be connected last, with one to the negative terminal of the working battery and the other to an unpainted metal surface on the dead car’s engine block or frame to complete the circuit.
 
This video demonstrates how to safely connect jumper cables to a car battery: 51sStan CravensYouTube · Oct 9, 2018
Step-by-Step Guide to Connecting Jumper Cables:

1. Turn off both vehicles: Opens in new tabEnsure the ignition keys are in the off position in both the car with the dead battery and the donor car. 
2. Connect the red (positive) cable to the dead battery: Opens in new tabAttach one red clamp to the positive (+) terminal of the dead battery. 
3. Connect the red (positive) cable to the donor battery: Opens in new tabAttach the other red clamp to the positive (+) terminal of the good battery on the donor vehicle. 
4. Connect the black (negative) cable to the donor battery: Opens in new tabAttach one black clamp to the negative (-) terminal of the donor vehicle’s good battery. 
5. Connect the black (negative) cable to the dead car’s frame: Opens in new tabAttach the final black clamp to an unpainted, unmoving metal part of the engine block or frame of the car with the dead battery. A slight spark may occur, which is normal. 

Why this order?

• Red first: Connecting the positive (red) cable to both batteries first creates a complete circuit without completing the negative side. 
• Last connection to metal: The last black clamp is attached to an unpainted metal surface on the dead car’s frame, not the negative terminal. This minimizes the risk of sparks, as the battery releases hydrogen gas that could cause an explosion. 

What is the correct order to take off jumper cables?

To remove jumper cables safely, disconnect them in the reverse order of connection: first the negative (black) clamp from the dead car, then the negative (black) clamp from the good car, followed by the positive (red) clamp from the good car, and finally the positive (red) clamp from the dead car. This sequence prevents sparks and potential damage to your vehicles’ electrical systems.
 
This video demonstrates the entire process of jump-starting a car, including how to disconnect the jumper cables: 1mAmericas Drivers EdYouTube · Mar 31, 2016
Here are the steps for removing jumper cables safely:

1. Turn off both engines: to ensure no electrical current is flowing. 
2. Disconnect the black (negative) clamp: from the grounded metal on the car with the dead battery. 
3. Disconnect the black (negative) clamp: from the negative terminal of the good (jumping) car’s battery. 
4. Disconnect the red (positive) clamp: from the positive terminal of the good (jumping) car’s battery. 
5. Disconnect the red (positive) clamp: from the positive terminal of the formerly stalled car’s battery. 

Important Safety Tips:

• Maintain distance: Keep at least two feet of distance between the vehicles while disconnecting the cables to prevent accidental contact. 
• Avoid sparks: Removing the negative cables first helps to prevent a short circuit, which can cause sparks and potentially damage electrical components or even the battery. 
• Clip them together: When not connected to a terminal, it’s a good idea to clip the red and black ends of the cables together to keep them separated and avoid accidental contact. 

Which car do I connect jumper cables to first?

When jump-starting a car, the red (+) jumper cable always connects to the positive terminal of the dead battery first. The second red clamp then goes to the positive terminal of the good (donor) car’s battery. The process continues by connecting the black (-) clamp to the negative terminal of the good car’s battery, and finally, the last black clamp connects to an unpainted metal part of the dead car’s frame, away from the battery.
 
Here is the detailed step-by-step process:

1. Park the cars: Position the working (donor) car close enough for the jumper cables to reach both batteries, ensuring the vehicles aren’t touching. 
2. Turn off both cars: Make sure both vehicles’ ignitions are off and the parking brakes are engaged. 
3. Open the hoods: Locate the batteries in both cars and ensure the cable clamps are separated. 
4. Connect the Red clamps: 
   • Connect one red (positive) clamp to the positive (+) terminal of the dead car’s battery. 
   • Connect the other red (positive) clamp to the positive (+) terminal of the good car’s battery. 
5. Connect the Black clamps: 
   • Connect one black (negative) clamp to the negative (-) terminal of the good car’s battery. 
   • Connect the final black (negative) clamp to an unpainted metal part of the dead car’s frame, away from the battery and any moving parts. This serves as a ground connection and helps prevent sparks near the battery. 
6. Start the working car: With all connections made, start the engine of the good (donor) car and let it run for a few minutes to charge the dead battery. 
7. Start the dead car: Attempt to start the car with the dead battery. 
8. Remove the cables: Once the dead car starts, disconnect the cables in the reverse order: first the black clamp from the dead car’s frame, then the black clamp from the good car’s battery, followed by the red clamp from the good car’s battery, and finally the red clamp from the dead car’s battery. 

What is the proper order to hook up a car battery?

And tighten it all the way down connect the positive. First. So your red one right there you got to remove that red cap let’s remove that. And then we’ll go ahead and connect the positive.