The correct order to jump-start a car—and why it matters

Connect the jumper cables in this order: 1) red clamp to the dead battery’s positive (+), 2) red clamp to the good battery’s positive (+), 3) black clamp to the good battery’s negative (−), 4) black clamp to an unpainted metal ground on the car with the dead battery. Start the donor car, then the dead car. Disconnect in reverse: 1) black from the ground, 2) black from the donor (−), 3) red from the donor (+), 4) red from the previously dead (+). This sequence reduces sparks and protects electronics. Below is a clear, detailed guide with safety notes for modern vehicles.

Why the connection order is critical

Sparking near a battery can ignite hydrogen gas released during charging. Placing the final (black) connection on a remote ground away from the dead battery, rather than its negative terminal, reduces that risk. It also helps protect sensitive vehicle electronics, which is increasingly important in newer cars with complex control modules.

Before you begin: safety and setup

Take a minute to prepare properly. A quick check of the vehicle type, battery markings, and your surroundings prevents damage and injury.

• Confirm both systems are 12V. Do not jump a 12V car from a 24V truck system.
• Check owner’s manuals: many cars have dedicated jump posts; hybrids/EVs have specific instructions and may not be safe donors.
• Inspect the dead battery: do not jump if it’s cracked, leaking, or frozen (bulged case, frost). Call for service instead.
• Use quality cables (4–6 gauge, clean clamps) or a reputable jump pack.
• Park vehicles close but not touching; set parking brakes; turn off lights and accessories; put transmissions in Park (auto) or Neutral (manual).
• Wear eye protection; keep loose clothing and cables clear of belts and fans.

These checks set a safe baseline and ensure your jump-start attempt won’t escalate into a hazardous situation or damage a modern vehicle’s electronics.

Exact connection order (car-to-car jump)

Follow this sequence precisely to minimize sparks at the battery and ensure current flows safely.

1. Attach red (+) clamp to the positive terminal of the dead battery (marked + or red).
2. Attach the other red (+) clamp to the positive terminal of the good (donor) battery.
3. Attach black (−) clamp to the negative terminal of the good (donor) battery.
4. Attach the final black (−) clamp to a solid, unpainted metal part of the engine or chassis on the car with the dead battery—ideally a designated ground point, bracket, or lifting eye, away from the battery.

This order keeps the final connection—and any spark—away from the dead battery, where hydrogen gas can accumulate.

Starting the vehicles and disconnecting safely

Once connected, bring the system up gradually to reduce strain and protect electronics.

1. Start the donor car and let it run 2–5 minutes. Lightly hold 1,500–2,000 rpm if safe to assist charging.
2. Try starting the car with the dead battery. If it doesn’t crank, wait another 2–5 minutes and try again. Avoid repeated rapid attempts.
3. Once the dead car starts, let both engines run for a minute to stabilize voltage.
4. Disconnect in exact reverse order:
   

   1. Black (−) clamp from the grounded metal on the previously dead car.
   2. Black (−) clamp from the donor battery.
   3. Red (+) clamp from the donor battery.
   4. Red (+) clamp from the previously dead battery.

Reverse-order removal avoids accidental short circuits and keeps any final arc away from the battery.

Using a portable jump pack

Jump packs are often safer for modern cars and simpler to use, but they must be connected correctly.

• Ensure the pack is sufficiently charged and switched off (if it has a power switch).
• Connect red clamp to the dead battery’s positive (+) post.
• Connect black clamp to a clean, unpainted metal ground on the vehicle (not the negative post), unless the pack’s instructions specify otherwise.
• Turn on the pack (if applicable) and start the vehicle. Avoid cranking more than 5–10 seconds at a time; rest 30–60 seconds between attempts.
• Turn off the pack, then remove clamps in reverse: black from ground, red from positive.

A quality jump pack with surge protection can reduce the risk of voltage spikes to sensitive electronics during starting.

Important cautions for modern vehicles

Not all vehicles should be jumped or used as donors in the same way. Here’s what to keep in mind with newer platforms.

• Start-stop and AGM batteries: Many cars use AGM batteries and dedicated jump posts—use them and follow the manual.
• Hybrids and EVs: Do not use them as donors. Most can be jump-started on the 12V system from a pack or another 12V source using designated terminals—follow the manufacturer’s guide.
• 48V mild hybrids: Do not connect to the 48V system. Use the vehicle’s 12V jump posts only.
• Lithium 12V batteries (LiFePO4): Follow the battery maker’s instructions; some have internal BMS protections and different procedures.

These distinctions protect high-voltage systems and ensure you don’t bypass designed safety features.

Troubleshooting: when the car still won’t start

If you’ve followed the sequence and the engine won’t crank, a few quick checks can pinpoint the issue.

• No click at all: Check clamp contact, corrosion on terminals, blown main fuse, or an immobilizer/security issue.
• Rapid clicking: The dead battery may be severely discharged or failed; let it charge longer or use a stronger pack.
• Cranks slowly but won’t start: Could be fuel/ignition; the battery may not be the root cause.
• Immediate stalling after start: Alternator or charging-system fault; battery light on dash is a clue—seek service.
• Hot or smoking cables: Stop immediately—cable gauge may be too light or clamps are not making good contact.

These symptoms help differentiate a simple low battery from deeper electrical or mechanical issues.

Aftercare: recharging and preventing a repeat

Jump-starting gets you going, but your battery likely isn’t fully charged and may need more attention.

• Drive 30–60 minutes or use a smart charger to reach full charge; alternators are not ideal for deep recharging.
• If the battery is over 4–5 years old or repeatedly goes flat, have it load-tested and consider replacement.
• Find the parasitic draw: Dome lights, glovebox lights, or plugged-in accessories can drain batteries overnight.
• Infrequent drivers: Use a battery maintainer to avoid sulfation.

Proper recharging and basic checks will extend battery life and reduce the chance of another no-start.

When not to jump—call a professional

Some situations are unsafe or likely to cause damage if you proceed.

• Cracked, leaking, bulging, or frozen battery.
• Strong rotten-egg smell (sulfur), excessive fizzing, or visible sparking.
• Unknown system voltage or unclear terminals/polarity.
• High-voltage system faults on hybrids/EVs.

If any of these apply, stop and seek roadside assistance or a professional technician.

Summary

Connect in this order: red to dead (+), red to donor (+), black to donor (−), black to ground on the dead car; start donor, then the dead car; disconnect in reverse. Use designated jump posts when provided, keep the final connection away from the battery to limit sparks, and recharge fully after. If the battery is damaged, the system is high-voltage, or the car still won’t start, call a professional.

What is the correct order for jumping a car?

To jump a car battery, connect jumper cables by first attaching the red clamp to the dead battery’s positive (+) terminal, then the other red clamp to the working car’s positive terminal. Next, connect the black clamp to the working car’s negative (-) terminal and the final black clamp to an unpainted metal surface on the dead car, away from the battery. After connecting both cars, start the working vehicle to charge the dead battery, then try to start the dead car.
 
This video demonstrates the complete process of jump-starting a car, including safety precautions: 50sCars.comYouTube · Oct 11, 2024
Step-by-Step Connection Guide:

1. Position the vehicles: Park the working car close to the dead car, but ensure they do not touch. 
2. Turn off both cars: Make sure both vehicles are completely off before connecting anything. 
3. Locate battery terminals: Identify the positive (+) and negative (-) terminals on each battery. 
4. Connect the red (positive) cables: 
   • Attach one red clamp to the dead battery’s positive (+) terminal. 
   • Attach the other red clamp to the working battery’s positive (+) terminal. 
5. Connect the black (negative) cables: 
   • Attach one black clamp to the working battery’s negative (-) terminal. 
   • Attach the final black clamp to an unpainted, unmoving metal part of the dead car (like the engine block). This helps prevent sparks near the battery. 
6. Start the working car: Let the working car run for a few minutes to begin charging the dead battery. 
7. Start the dead car: Attempt to start the dead car. 
8. Disconnect the cables: Once the dead car starts, disconnect the jumper cables in the reverse order: black negative clamp from the dead car’s metal surface, then the black negative clamp from the working car, then the red positive clamp from the working car, and finally the red positive clamp from the dead battery. 

This video shows the step-by-step process of disconnecting the cables after a successful jump-start: 58sAAA Connect Video Hub | Auto Club GroupYouTube · Sep 23, 2024
Why the Order Matters:
The correct order is crucial for safety. Connecting the last negative clamp to a grounded metal surface helps prevent sparks, which can be a fire or explosion hazard with lead-acid batteries, especially if they are venting hydrogen gas. 
After the Jump:
Let the jump-started car run for at least 15-20 minutes to allow the alternator to fully charge the battery.

In what order should I jump start?

To jump-start a car, the jumper cable connection order is crucial for safety. Connect the red clamp to the positive terminal of the dead battery first, then the other red clamp to the positive terminal of the working (donor) battery. Next, connect the black clamp to the negative terminal of the working battery, and finally, connect the other black clamp to an unpainted metal surface on the dead car’s engine block away from the battery. Disconnect the cables in the reverse order.
 
Connecting the Jumper Cables

1. Red to Dead Battery: Connect the red (positive) clamp of the jumper cable to the positive terminal (+) of the car with the dead battery. 
2. Red to Donor Battery: Connect the other red (positive) clamp to the positive terminal (+) of the car with the working battery. 
3. Black to Donor Battery: Connect the black (negative) clamp to the negative terminal (-) of the car with the working battery. 
4. Black to Ground: Connect the final black (negative) clamp to an unpainted metal surface on the engine block of the car with the dead battery, away from the battery itself. 

Starting and Disconnecting

1. Start the Working Car: Start the engine of the vehicle with the good (donor) battery and let it run for a few minutes. 
2. Start the Dead Car: Try to start the engine of the car with the dead battery. 
3. Disconnect in Reverse Order: Once the dead car’s engine is running, disconnect the cables in the following reverse order: 
   • Black clamp from the engine block. 
   • Black clamp from the donor vehicle’s negative terminal. 
   • Red clamp from the donor vehicle’s positive terminal. 
   • Red clamp from the dead battery. 

This video demonstrates the proper way to jump start a car: 58sAAA Connect Video Hub | Auto Club GroupYouTube · Sep 23, 2024
Important Safety Tips

• Ensure both cars are turned off and the parking brakes are engaged. 
• Make sure the cars are close enough to reach but not touching. 
• Avoid contact between the positive and negative cables to prevent sparks. 
• If the dead car doesn’t start after a few tries, there may be a more serious issue requiring a mechanic. 

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.

What are the 5 steps to jumpstart a car?

How to Use Jumper Cables to Start a Car

1. Step 1: Park the Cars Safely.
2. Step 2: Turn Both Cars Off.
3. Step 3: Find the Battery Terminals.
4. Step 4: Connect the Red Jumper Cable Clamps.
5. Step 5: Connect the Black Jumper Cable Clamps.
6. Step 6: Jump-Start the Car.
7. Step 7: Disconnect the Black Cable Clamps.