The Correct Order to Hook Up Jumper Cables—and Why It Matters

Connect the cables in this order: 1) Red clamp to the dead battery’s positive (+) terminal, 2) Red clamp to the good battery’s positive (+) terminal, 3) Black clamp to the good battery’s negative (−) terminal, 4) Black clamp to an unpainted metal ground on the vehicle with the dead battery (not its negative terminal). Start the vehicle and disconnect in reverse order. This method minimizes sparking near the dead battery and protects sensitive electronics, which is why most automakers and roadside services recommend it.

Step-by-Step Connection Order

The sequence below prioritizes safety and reduces the risk of sparks and damage to vehicle electronics. Make sure both vehicles are off, in Park (or Neutral for manual transmissions), with parking brakes engaged and accessories turned off.

1. Attach the red (positive) clamp to the dead battery’s positive (+) terminal.
2. Attach the other red (positive) clamp to the good battery’s positive (+) terminal.
3. Attach the black (negative) clamp to the good battery’s negative (−) terminal.
4. Attach the remaining black (negative) clamp to a clean, unpainted metal ground on the engine block or chassis of the car with the dead battery—avoid the dead battery’s negative terminal.

This order ensures the final connection is away from the dead battery, where hydrogen gas can accumulate, reducing the chance of a spark igniting it.

Starting and Disconnecting Safely

After the cables are connected, take the following steps to start the vehicle and then remove the cables in the safest possible sequence.

1. Start the engine of the vehicle with the good battery and let it idle for 2–5 minutes.
2. Try starting the vehicle with the dead battery. If it doesn’t start, wait another 2–3 minutes and try again; avoid cranking longer than 10 seconds at a time.
3. Once the dead vehicle starts, keep both engines running for a minute to stabilize voltage.
4. Disconnect in reverse order: remove the black clamp from the grounded metal on the previously dead car, then the black clamp from the good battery, then the red from the good battery, and finally the red from the previously dead battery.
5. Drive the revived vehicle for at least 20–30 minutes to help recharge, but plan for a proper battery test and, if needed, an external charger for a full recovery.

Reversing the order on removal prevents accidental short circuits and keeps sparks away from the battery that was just revived.

Why the Order Matters

Modern vehicles carry sensitive electronics and high-current systems. The prescribed clamp sequence addresses key safety and technical concerns.

• Reduces spark risk near hydrogen gas emitted by charging batteries.
• Protects ECUs and sensors from voltage spikes during connection and startup.
• Ensures a solid ground path, improving starting success and safety.

Following the correct sequence is a simple step that prevents common and costly mistakes during a jump-start.

Common Mistakes to Avoid

These frequent errors can damage vehicles or cause injury; avoiding them keeps the process straightforward and safe.

• Clamping the final black lead to the dead battery’s negative terminal instead of a remote ground.
• Letting clamps touch each other or slip onto moving parts like belts or fans.
• Mixing up polarity (reversing red and black), which can blow fuses or damage ECUs.
• Jumping a cracked, leaking, swollen, or frozen battery—replace or thaw safely first.
• Using mismatched systems (for example, trying to jump a 24V truck from a 12V car).

A quick visual check of cables, terminals, and the battery case can prevent most of these problems before they occur.

Special Cases and Warnings

Not every vehicle should be jumped the same way. Consult the owner’s manual when in doubt, especially with newer powertrains and nontraditional battery locations.

• Hybrids/EVs: Many have specific 12V jump points or procedures; some should not be jump-started from another vehicle. Never attempt to jump the high-voltage system.
• Start-stop vehicles (AGM/EFB batteries): Safe to jump if the manual allows; use the designated under-hood posts if the battery is remote (trunk/seat).
• Diesels and dual-battery setups: Use the posted jump terminals or the battery tied to the starter, per the manual.
• Portable jump packs: Follow the same order; ensure the pack is rated for the engine and is fully charged.
• Corroded terminals: Clean lightly for good contact; severe corrosion may require service before attempting a jump.

Manufacturer guidance always takes precedence; incorrect procedures can void warranties or damage electrical systems.

Quick Troubleshooting if It Won’t Start

If the engine still won’t turn over, a few targeted checks can reveal the issue without causing further harm.

1. Recheck all clamps for solid metal-to-metal contact and correct polarity.
2. Let the good vehicle run a bit longer to add charge, then try again.
3. Turn off high-draw accessories (lights, HVAC, audio) on the dead vehicle.
4. Inspect for blown fuses related to the starting/charging circuit.
5. Consider a failing battery or starter; a load test or professional diagnosis may be needed.

Persistent failure after correct procedure often signals a battery at end-of-life or a separate electrical fault.

Essential Tools Checklist

Having the right gear on hand makes the process safer and more reliable, especially in low-light or adverse conditions.

• Quality jumper cables (4–6 gauge, 12–20 feet, with solid clamps)
• Portable jump starter (optional but convenient)
• Work gloves and eye protection
• Wire brush or terminal cleaner
• Flashlight or headlamp

Durable cables and basic protective equipment reduce risk and improve your chances of a first-try start.

Summary

Hook up jumper cables in this order: red to dead (+), red to good (+), black to good (−), black to an unpainted metal ground on the dead car—then disconnect in reverse. This sequence minimizes sparks and protects electronics, making it the safest, most widely recommended approach for a successful jump-start.

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 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.

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.

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.