Which car should the jumper cables go on first?

Attach the red positive clamp to the dead car’s positive battery terminal first, then connect the red clamp to the donor car’s positive terminal, the black clamp to the donor car’s negative terminal, and finally the remaining black clamp to an unpainted metal ground on the dead car. This sequence minimizes sparks near the good battery and helps protect sensitive electronics in both vehicles. Below, we explain why the order matters and how to do it safely and correctly.

Why the order matters

Modern vehicles pack sensitive electronics, from engine control units to smart charging systems. Connecting in the recommended order limits current surges and keeps the final “sparking” connection away from the battery, where hydrogen gas may be present. Starting at the dead car’s positive terminal and ending on the dead car’s chassis ground reduces the risk of battery explosion and electrical damage.

Step-by-step connection order

The following instructions cover the safest, widely recommended method for jump-starting a vehicle with a 12‑volt system. Always verify your owner’s manual for model-specific guidance or dedicated jump-start posts.

1. Park the cars nose-to-nose (but not touching) and set both parking brakes. Turn off all accessories and lights.
2. Confirm both vehicles use negative-ground 12V systems (most do). Avoid jumping hybrids/EVs without following manufacturer instructions.
3. Inspect both batteries for cracks, leaks, or heavy corrosion. If damaged, do not attempt a jump.
4. Identify the positive (+, usually red) and negative (−, usually black) terminals, or the designated jump posts.
5. Connect red clamp to the dead car’s positive terminal (+).
6. Connect the other red clamp to the donor car’s positive terminal (+).
7. Connect black clamp to the donor car’s negative terminal (−).
8. Connect the remaining black clamp to a solid, unpainted metal point on the dead car (engine block or chassis ground), away from the battery.
9. Start the donor car and let it run for 2–5 minutes to charge the dead battery.
10. Attempt to start the dead car. If it doesn’t start, wait another 2–3 minutes and try again.

Following this order keeps the highest-risk connection—the final ground clamp—away from the battery, reducing the chance of igniting gases and protecting electronics from voltage spikes.

Disconnecting order (once the dead car starts)

Remove the cables carefully in reverse order to avoid accidental short circuits.

1. Remove the black clamp from the dead car’s ground.
2. Remove the black clamp from the donor car’s negative terminal (−).
3. Remove the red clamp from the donor car’s positive terminal (+).
4. Remove the red clamp from the formerly dead car’s positive terminal (+).
5. Keep the once-dead car running for at least 20–30 minutes or drive to let the alternator recharge the battery.

Reversing the sequence during disconnection prevents accidental arcing between exposed clamps and battery posts, reducing the risk of damage or injury.

Safety notes and exceptions

Jump-starting is straightforward, but there are crucial precautions and special cases for modern vehicles.

• Use dedicated jump posts if provided; many cars hide the battery and require using labeled terminals under the hood.
• Avoid connecting both black clamps to the dead battery; use a chassis ground on the dead car to minimize sparks near the battery.
• Do not jump a visibly damaged, frozen, or leaking battery.
• Hybrids and EVs: Never connect to high-voltage systems. Only use the 12V jump posts per the owner’s manual. Some hybrids/EVs should not be used as donor vehicles.
• Start-stop/AGM/EFB batteries: Follow manufacturer guidance; charging behavior and posts may differ from traditional flooded batteries.
• Use cables rated for the job (e.g., 4–6 gauge for most cars; thicker for trucks) with intact insulation and solid clamps.
• Keep metal jewelry, loose clothing, and tools away from terminals to prevent short circuits.
• If the donor car’s engine runs roughly when connected, increase idle slightly or disconnect and reassess to protect its alternator.

These practices reduce hazards and account for the variety of modern charging systems, ensuring a safer jump-start for both vehicles.

Common mistakes to avoid

Small errors can lead to big problems when handling high current.

• Reversing polarity (red to − or black to +) can fry electronics instantly.
• Clamping onto painted, oily, or corroded surfaces that prevent a good connection.
• Letting clamps touch each other once any end is connected to a battery.
• Rushing to start the dead car without a brief charging period from the donor vehicle.
• Assuming a successful jump means the battery is fine; it may still be failing or the alternator may be weak.

Avoiding these pitfalls helps ensure a successful start and protects both vehicles from unintended damage.

If the car still won’t start

Persistent no-start after a correct jump suggests a deeper issue.

• Check for an interior light or accessory left on that re-drained the battery.
• Inspect battery terminals and grounds for hidden corrosion or loose connections.
• Listen for a click but no crank—could indicate a failing starter or poor ground.
• Use a multimeter: a healthy resting battery is around 12.6V; under 12.0V suggests deep discharge or failure.
• Consider roadside assistance or a load test at an auto parts store to evaluate battery and alternator health.

These checks help distinguish between a simple drained battery and a broader charging or starting system fault.

Summary

Connect the jumper cables beginning with the dead car’s positive terminal, then the donor’s positive, the donor’s negative, and finally a chassis ground on the dead car. This order reduces sparks at the battery and helps protect electronics. Use proper cables, follow any vehicle-specific jump posts, and disconnect in reverse order. If the vehicle still won’t start, test the battery and charging system before replacing parts.

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.

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 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. 

Which car do you hook up first with jumper cables?

When jumping a car, you should always connect the red jumper cable first to the positive terminal of the dead battery to prevent sparks that could ignite gases and cause an explosion. The positive cable is then attached to the positive terminal of the good battery, and the black (negative) cable is attached to the negative terminal of the good battery, and finally, the other black cable is connected to an unpainted metal surface on the frame or engine of the dead car.
 
Connection Steps

1. Red clamp to the dead battery Opens in new tab: Attach the red (positive) clamp of the jumper cable to the positive (+) terminal of the dead car’s battery. 
2. Red clamp to the good battery Opens in new tab: Attach the other red (positive) clamp to the positive (+) terminal of the good car’s battery. 
3. Black clamp to the good battery Opens in new tab: Connect one black (negative) clamp to the negative (-) terminal of the good car’s battery. 
4. Black clamp to a metal surface on the dead car Opens in new tab: Connect the remaining black (negative) clamp to an unpainted, unmoving metal part of the engine block or chassis of the car with the dead battery. This provides a ground and is the last connection, keeping any spark away from the dead battery. 

After Connecting 

1. Start the good car’s engine .
2. Let the good car run for a few minutes to allow power to transfer to the dead battery.
3. Attempt to start the engine of the car with the dead battery.
4. Once the dead car is running, run both engines for about 15 minutes before disconnecting the cables.

Important Safety Tip: Always disconnect the cables in the reverse order they were connected, ending with the black cable from the metal surface on the dead car.