Jumper Cables 101: Which Clamp Goes On First?

The first clamp to attach is the red positive (+) clamp to the dead battery’s positive terminal, followed by the red clamp to the good battery’s positive, then the black negative (–) clamp to the good battery’s negative, and finally the black clamp to an unpainted metal ground on the dead car. This sequence minimizes sparks near the battery and reduces the risk of igniting hydrogen gas. Below, we explain the reasoning and provide a step-by-step guide to connect and disconnect safely.

The Correct Order to Attach Jumper Cables

Proper sequencing matters because lead-acid batteries can emit flammable hydrogen gas. Making the final connection away from the dead battery helps prevent dangerous sparking at the source. Follow this order to connect cables safely.

1. Red to dead: Attach the red positive (+) clamp to the positive terminal of the dead battery.
2. Red to donor: Attach the other red positive (+) clamp to the positive terminal of the good (donor) battery.
3. Black to donor: Attach the black negative (–) clamp to the negative terminal of the good battery.
4. Black to ground on dead vehicle: Attach the remaining black clamp to a clean, unpainted metal surface on the engine block or chassis of the dead vehicle, away from the battery and moving parts.

Completing the sequence in this order reduces the chance of a spark igniting gases around the dead battery and helps protect both vehicles’ electrical systems.

Step-by-Step: Starting the Disabled Vehicle

With the cables attached in the correct order, bring the vehicles to a safe state before attempting to start the disabled car. These steps help ensure a controlled start and avoid electrical surges.

1. Ensure both vehicles are in Park (automatic) or Neutral (manual), with parking brakes on, ignitions off, and lights/accessories off.
2. Start the donor vehicle and let it idle for 2–5 minutes to charge the dead battery.
3. Attempt to start the disabled vehicle. If it doesn’t start, wait another 2–5 minutes and try again.
4. Once the disabled vehicle starts, keep both engines running for a minute to stabilize voltage.

If the disabled vehicle fails to start after several attempts, stop and reassess: the battery may be severely discharged, the terminals corroded, or there may be a deeper mechanical or electrical issue.

How to Disconnect Jumper Cables Safely

Disconnecting in the reverse order of the connection process helps prevent voltage spikes and sparks near the battery. Use the following sequence for a safe removal.

1. Remove the black clamp from the grounded metal on the previously dead vehicle.
2. Remove the black clamp from the donor vehicle’s negative (–) terminal.
3. Remove the red clamp from the donor vehicle’s positive (+) terminal.
4. Remove the red clamp from the previously dead vehicle’s positive (+) terminal.

Keep the clamps from touching each other or any moving parts as you remove them. Afterward, allow the revived vehicle to run for at least 20–30 minutes or drive to recharge the battery.

Why This Order Matters

The final connection to a chassis ground on the dead car keeps any potential spark away from the battery, where explosive gases may accumulate. This practice is recommended by many automakers and safety organizations because it reduces ignition risk and helps protect sensitive electronics from voltage spikes.

Safety Tips and Common Mistakes

Jump-starting is straightforward, but small errors can cause damage or injury. Keep the following cautions in mind to work safely and effectively.

• Match systems: Only jump a 12-volt lead-acid system with another 12-volt source.
• Polarity matters: Red to positive (+), black to negative (–). Never cross them.
• Use a solid ground: Clamp to clean, unpainted metal on the dead car; avoid fuel lines and moving parts.
• Inspect batteries: Do not jump a cracked, leaking, or frozen battery; seek service instead.
• Protect electronics: Turn off accessories; avoid revving excessively while connected.
• Wear eye protection and gloves: Batteries can vent acid and gas.
• Keep vehicles from touching: Prevents unintended grounding paths.
• Consult the manual: Some vehicles have dedicated jump posts; use them if provided.

Following these precautions lowers the risk of fire, injury, or damage to costly electronic components, and it improves the odds of a successful jump-start.

Special Cases: Hybrids and EVs

Hybrids and electric vehicles often have specific jump-start procedures and clearly marked 12-volt jump points. You typically can jump-start a hybrid’s 12-volt system, but never attempt to jump the high-voltage traction battery. Some EVs can provide a jump to another car’s 12-volt battery, while others should not. Always consult the owner’s manual for the exact steps and any limitations for your model.

What If It Still Won’t Start?

If the car remains dead after proper procedure, check for corroded terminals, loose clamps, or a poor ground connection. A battery older than about 3–5 years may no longer hold a charge. Alternator failures, blown fuses, or starter issues can also prevent starting; at that point, professional diagnosis is recommended.

Summary

Attach jumper cables in this order: red to the dead battery’s positive, red to the donor’s positive, black to the donor’s negative, and black to an unpainted metal ground on the dead vehicle. Disconnect in reverse. This sequence minimizes sparking near the battery and protects both vehicles’ electrical systems. Always follow safety best practices and your vehicle’s manual, especially for hybrids and EVs.

What is the correct order to attach jumper cables?

It goes like. This red to the dead. Red to the good black to the good. Then under the hood. Now let’s watch as Brian from Henderson Auto puts all of that into action.

In what order should I jump a car?

Connect the red clamp to the positive post on the dead battery. Connect the other red clamp to the positive post on the working battery. Connect the black clamp to the negative post on the working battery. Connect the last black clamp to an unpainted metal surface of your car.

Is there an order for putting on jumper cables?

Make sure you have followed these steps in proper order: red clip from booster cable to positive terminals, then black clip from booster cable to negative terminals. Once all connections are made, start up your working vehicle and let it run for a few minutes before attempting to start your dead battery’s engine.

Do you attach red or black first?

When jump-starting a car, connect the red (positive) jumper cable first to the positive terminals of both batteries, and then connect the black (negative) jumper cable to the negative terminal of the donor car and to an unpainted metal surface on the dead car. When removing the cables, follow the process in reverse: detach the black cable from the dead car, then the black cable from the donor car, and finally the red cables. 
Step-by-Step Connection Guide

1. RED to DEAD: Connect one red (positive) cable to the positive terminal of the dead battery. 
2. RED to DONOR: Connect the other red (positive) cable to the positive terminal of the donor car’s battery. 
3. BLACK to DONOR: Connect the black (negative) cable to the negative terminal of the donor battery. 
4. BLACK to METAL: Connect the final black (negative) cable to a solid, unpainted metal part of the dead car’s engine or chassis, such as a bolt or bracket, but not directly to the negative terminal. 

Step-by-Step Disconnection Guide

1. BLACK from DEAD CAR: Disconnect the black cable from the unpainted metal surface on the dead car. 
2. BLACK from DONOR CAR: Disconnect the black cable from the negative terminal of the donor battery. 
3. RED from DONOR CAR: Disconnect the red cable from the donor battery. 
4. RED from DEAD CAR: Disconnect the red cable from the dead battery. 

Why This Order?

• Connecting the red (positive) cables first allows for a continuous circuit with a single potential. 
• Connecting the black (negative) cable last to an unpainted metal surface minimizes the risk of sparks, preventing potential battery explosions from flammable hydrogen gas emitted by the battery.