How to Attach Jumper Cables in the Correct Order

The correct order is: red clamp to the dead battery’s positive (+), red clamp to the good battery’s positive (+), black clamp to the good battery’s negative (−), and black clamp to a clean, unpainted metal ground on the dead car (not its negative terminal). To remove, reverse that sequence: black from the ground, black from the good battery negative, red from the good battery positive, red from the formerly dead battery positive. This sequence reduces the risk of sparks, protects electronics, and improves your odds of a safe start.

What to Do Before You Begin

Before attaching any cables, ensure both vehicles and conditions are safe. These checks prevent injury, protect sensitive electronics, and help the jump start work the first time.

• Confirm both systems are 12-volt; do not jump between mismatched voltages (e.g., 12V to 24V).
• Park cars nose-to-nose or side-by-side without touching; engage parking brakes; put transmissions in Park (automatic) or Neutral (manual).
• Turn off both ignitions and all accessories (lights, HVAC, infotainment); remove the key where applicable.
• Identify battery terminals: “+” (positive, usually red cover) and “−” (negative). Many modern cars have remote jump posts—use them if provided.
• Inspect for damage: do not jump a leaking, swollen, or frozen battery; seek professional help instead.
• Wear eye protection and gloves if available; keep flames and smoking materials away from batteries.

Completing these steps first minimizes hazards and avoids common causes of failed jump starts, such as reversed polarity or poor connections.

Step-by-Step: Attach the Jumper Cables

This sequence connects the batteries while keeping sparks away from the weak battery, where hydrogen gas may be present. Follow each step in order.

1. Attach red (+) clamp to the dead car’s positive terminal (+) or designated positive jump post.
2. Attach the other red (+) clamp to the good car’s positive terminal (+) or positive jump post.
3. Attach black (−) clamp to the good car’s negative terminal (−) or negative jump post.
4. Attach the other black (−) clamp to a solid, unpainted metal point on the dead car’s engine block or chassis, away from the battery and moving parts.
5. Start the good car and let it run at a fast idle (around 1,500–2,000 rpm) for 2–5 minutes to put some charge into the dead battery.
6. Attempt to start the dead car. If it doesn’t start, wait another 2–3 minutes and try again.
7. Once the dead car starts, keep both cars running for a couple of minutes to stabilize voltage.
8. If the dead car fails to start after several attempts, stop and seek service; prolonged cranking can damage starters and wiring.

This order prioritizes correct polarity and safe grounding. Using a solid chassis ground on the dead vehicle moves potential sparks away from the battery and often provides a better electrical connection.

Correct Order to Remove the Cables

Disconnecting in the proper reverse order prevents short circuits and protects both vehicles’ electronics from voltage spikes.

1. Remove the black (−) clamp from the dead car’s chassis/engine ground.
2. Remove the black (−) clamp from the good car’s negative terminal/post.
3. Remove the red (+) clamp from the good car’s positive terminal/post.
4. Remove the red (+) clamp from the formerly dead car’s positive terminal/post.

After removal, keep the revived car running for at least 20–30 minutes or drive it to allow the alternator to recharge the battery; otherwise, it may stall again.

Why the Final Ground Goes on the Dead Car’s Chassis, Not the Battery

Grounding on the dead vehicle’s metal frame or engine is a long-standing safety practice supported by automakers and safety organizations.

• Reduces spark risk near the battery, where hydrogen gas may accumulate and ignite.
• Often provides a cleaner, lower-resistance connection than a corroded negative terminal.
• Keeps clamps and hands away from crowded battery areas and sensitive battery-mounted sensors.

Use a sturdy, unpainted metal point, such as a bracket or engine lifting eye. Avoid moving parts, painted surfaces, or thin sheet metal.

Common Mistakes to Avoid

These errors can damage electronics or cause injury. A few quick checks help you avoid them.

• Reversing polarity (crossing red/black) — this can blow fuses or damage ECUs instantly.
• Clamping on paint, plastic, or loose/corroded terminals — results in weak or no connection.
• Letting clamps touch each other after one end is connected — can cause arcing.
• Jumping a damaged, frozen, or leaking battery — explosion and acid risks.
• Using a 24V source on a 12V car (e.g., from a truck) — likely to destroy electronics.
• Revving excessively or cranking continuously — overheating and electrical stress.

If anything seems unusual (smoke, melting insulation, strong sulfur smell), stop immediately and disconnect safely.

Special Cases and Cautions

Vehicles with Start-Stop Systems or Sensitive Electronics

Many modern cars provide designated jump-start posts and may discourage connecting directly to the battery. Use the marked posts, follow the owner’s manual, and avoid cheap cables lacking surge protection. A quality jump pack with reverse-polarity and surge protection is often safer than using another car.

Hybrids and Electric Vehicles

Do not attempt to jump high-voltage traction batteries. Some EVs/hybrids allow you to jump or be jumped on the 12V auxiliary system using clearly labeled posts; others advise against providing a jump to another vehicle. Always follow the vehicle’s manual. If allowed, use the same connection order to the 12V posts only.

Remote Terminals and Battery Location

If the battery is under a seat, in the trunk, or otherwise inaccessible, use the under-hood positive and negative/jump-ground posts provided by the manufacturer. The connection order remains the same.

When Not to Jump

Skip the jump and call for service if the battery is frozen, the case is bulging, there’s visible leakage, or cables/terminals are melted or severely corroded. Jumping in these conditions is dangerous.

Troubleshooting If the Car Won’t Start

If the engine still won’t start after following the correct order, these checks can help isolate the problem.

• Recheck clamps for solid metal contact; clean light corrosion if necessary.
• Wait longer with the donor car running; extremely discharged batteries may need several minutes of charging.
• Try a different ground point on the dead car’s engine or chassis.
• Listen for clicks: single click may indicate starter/solenoid; rapid clicking suggests very low battery or poor connection.
• Consider a failed battery, blown fuse, or immobilizer issue; professional testing may be needed.

Persistent no-start after proper connections often points to a battery past its service life or an underlying electrical/starting-system fault.

Quick Reference

Use this snapshot to double-check the sequence before you connect or disconnect.

• Connect in this order: red to dead (+), red to good (+), black to good (−), black to dead car chassis/engine metal.
• Disconnect in this order: black from chassis/engine, black from good (−), red from good (+), red from formerly dead (+).

Following this sequence keeps sparks away from the battery and protects both vehicles’ electronics.

Summary

Attach jumper cables in the sequence red-dead (+), red-good (+), black-good (−), black-dead chassis, then remove in exact reverse. Use designated jump posts when provided, avoid jumping damaged or mismatched systems, and prioritize safe, clean connections. Done correctly, this method is the safest, most reliable way to bring a dead 12V battery back to life long enough to get you moving.

Does the order you put on jumper cables matter?

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.

What is the correct order to hook up jumper cables?

To properly hook up jumper cables, first connect the red (positive) clamp to the dead car’s positive battery terminal, then the other red clamp to the live car’s positive terminal. Next, connect the black (negative) clamp to the live car’s negative terminal. Finally, connect the last black clamp to an unpainted metal surface on the dead car’s engine block, a safe distance from the battery, to prevent sparks.
 
This video explains the steps to jump-start a car: 50sCars.comYouTube · Oct 11, 2024
Step-by-step Connection:

1. Park safely: Position the cars close enough to reach the batteries but without touching. Turn both cars off. 
2. Connect the Red Clamps: 
   • Attach one red clamp to the positive (+) terminal of the dead battery. 
   • Attach the other red clamp to the positive (+) terminal of the good battery in the working car. 
3. Connect the Black Clamps: 
   • Attach one black clamp to the negative (-) terminal of the good battery. 
   • Attach the final black clamp to a sturdy, unpainted metal part of the dead car’s engine (like a bracket or bolt). This acts as a “ground” and keeps the last connection away from the battery, reducing the risk of an explosion from hydrogen gas. 

Important Tips:

• Safety First: Always ensure the cables are away from moving parts like fans or belts. 
• Avoid Sparks: Connecting the last cable to the dead battery’s negative terminal can cause a spark that might ignite battery gases. 
• Start the Good Car: Start the car with the good battery and let it run for a few minutes to charge the dead battery. 
• Start the Dead Car: Then, try to start the car with the dead battery. 
• Disconnect Safely: Disconnect the cables in the reverse order of connection, starting with the black clamp from the dead car’s ground. 

Is there an order for jumper cables?

Jump-starting a car safely and effectively requires following a 6-step process: Positioning the booster vehicle, securely connecting the jumper cables in the correct order (positive to dead battery, positive to booster, negative to booster, then negative to grounded metal), starting the booster vehicle, and …

Which jumper cable comes off first?

You should remove the jumper cables in the reverse order they were connected, starting with the black (negative) cable from the dead car’s frame or engine, then the black (negative) cable from the good battery, followed by the red (positive) cable from the good battery, and finally the red (positive) cable from the dead battery. This order helps prevent sparks and potential electrical damage or fire by ensuring the last connection made is a grounding point, away from the battery’s hydrogen gas.
 
This video demonstrates the proper connection and disconnection of jumper cables: 59sChrisFixYouTube · Feb 13, 2015
Here’s the complete disconnection process:

1. Remove the black (negative) clamp: from the unpainted metal ground point on the dead car. 
2. Remove the black (negative) clamp: from the positive terminal of the good (booster) car’s battery. 
3. Remove the red (positive) clamp: from the positive terminal of the good (booster) car’s battery. 
4. Remove the red (positive) clamp: from the positive terminal of the dead car’s battery. 

Why this order is important:

• Prevents sparks near the battery: Opens in new tabConnecting and disconnecting the negative (black) ground clamp last minimizes the risk of sparking near the battery. 
• Avoids electrical surges: Opens in new tabDisconnecting in this order reduces the chance of electrical surges that could damage sensitive vehicle components. 
• Reduces the risk of fire: Opens in new tabBatteries can release flammable hydrogen gas, and a spark near the battery from a premature removal of the negative cable could cause a fire.