Which Jumper Cable Goes on First? Safe, Step-by-Step Guidance

The first connection should be the red (positive) clamp to the dead vehicle’s positive (+) battery terminal. Then attach the other red clamp to the donor battery’s positive terminal, connect the black (negative) clamp to the donor battery’s negative (–) terminal, and finish by clamping the remaining black lead to an unpainted metal ground on the disabled vehicle—not its battery. This sequence minimizes sparks near the battery and reduces the risk of ignition from hydrogen gas.

Why the Order Matters

Car batteries can emit hydrogen gas, which is flammable. Connecting in the correct order keeps the final spark away from the battery, where gas is most concentrated. Automakers and roadside-assistance organizations recommend the positive-first, ground-last method to reduce the risk of short circuits, component damage, and injury.

How to Connect Jumper Cables Correctly

The following steps explain the recommended sequence for connecting jumper cables between a disabled vehicle (dead battery) and a donor vehicle (good battery). Ensure both vehicles are 12-volt systems and follow each step carefully.

1. Park the vehicles nose-to-nose but not touching; set both in Park (or Neutral for manual), engage parking brakes, and turn off engines and accessories.
2. Locate the correct jump-start points. Many modern cars have remote positive/negative posts; use them if provided.
3. Attach the red (positive) clamp to the dead vehicle’s positive (+) terminal/post.
4. Attach the other red (positive) clamp to the donor vehicle’s positive (+) terminal/post.
5. Attach the black (negative) clamp to the donor vehicle’s negative (–) terminal/post.
6. Attach the remaining black (negative) clamp to a solid, unpainted metal point on the disabled vehicle (engine block bracket or chassis ground), away from the battery and moving parts.
7. Start the donor vehicle and let it idle for a minute or two to build charge in the dead battery.
8. Attempt to start the disabled vehicle. If it doesn’t start, wait another minute and try again. Avoid cranking for more than 10 seconds at a time.

Following this order keeps the final connection—and any potential spark—away from the dead battery, while ensuring current flows safely between the vehicles.

How to Disconnect Safely (Reverse Order)

Once the disabled vehicle is running, remove the cables in reverse to avoid arcing and accidental short circuits.

1. Remove the black (negative) clamp from the grounded metal point on the formerly disabled vehicle.
2. Remove the black (negative) clamp from the donor vehicle’s negative (–) terminal/post.
3. Remove the red (positive) clamp from the donor vehicle’s positive (+) terminal/post.
4. Remove the red (positive) clamp from the formerly disabled vehicle’s positive (+) terminal/post.
5. Keep the engine of the revived vehicle running for at least 20–30 minutes or drive to allow the alternator to replenish the battery.

Reversing the connection sequence helps prevent voltage spikes and reduces the risk of sparks near the battery.

Common Mistakes and Safety Tips

These practical reminders help prevent damage and keep you safe during a jump-start.

• Never let clamps touch each other or touch both terminals at once.
• Do not connect the final black clamp to the dead battery’s negative terminal; use a clean, unpainted metal ground away from the battery.
• Check batteries for cracks, leaks, or heavy corrosion; do not jump a damaged or frozen battery.
• Match system voltages (most passenger vehicles use 12V). Do not attempt to jump 24V systems with 12V equipment.
• Turn off lights, HVAC, and accessories before connecting; remove metal jewelry and wear eye protection if available.
• Consult the owner’s manual: some vehicles have designated jump points; some hybrids or luxury models specify special procedures.
• If the engine doesn’t start after a few tries, the battery may be beyond recovery or there may be another fault (starter, alternator, fuses).

Sticking to these precautions reduces the likelihood of electrical damage and personal injury during a jump-start.

Special Cases: Hybrids, EVs, and Start-Stop Vehicles

Hybrids and vehicles with start-stop systems usually still use a 12V auxiliary battery, but they often require you to use specific jump posts and procedures outlined in the manual. Full battery-electric vehicles (EVs) cannot be “jumped” in the traditional sense for their high-voltage pack, but many have a 12V system that can be jump-started to power up control electronics; always follow the manufacturer’s instructions. If unsure, call roadside assistance.

Summary

Connect the red clamp to the dead battery’s positive terminal first, then red to donor positive, black to donor negative, and finally black to an unpainted metal ground on the dead vehicle. Disconnect in reverse. This order minimizes sparks near the battery and is the widely recommended, safest way to use jumper cables.

Does it matter which jumper cable you hook up first?

Yes, it matters which jumper cable you connect first and last, for safety reasons related to sparking and potential hydrogen gas ignition. To connect them safely, you should always connect the positive (red) cables to the positive (+) terminals on both batteries first. Then, connect the negative (black) cable to the negative (-) terminal on the donor car’s battery. Finally, connect the last negative (black) cable to an unpainted metal part of the dead car’s frame, away from the battery. This grounding method prevents a large spark that could ignite hydrogen gas near the battery.
 
This video explains the proper order for connecting jumper cables to a car battery: 1mKPTV FOX 12 | Local news, weather Portland, OregonYouTube · Oct 10, 2024
Connection Order (Connecting)

1. Red to Dead Battery: Opens in new tabConnect the red (+) clamp to the positive (+) terminal of the dead battery. 
2. Red to Good Battery: Opens in new tabConnect the other red (+) clamp to the positive (+) terminal of the good, “donor” battery. 
3. Black to Good Battery: Opens in new tabConnect the black (-) clamp to the negative (-) terminal of the good, “donor” battery. 
4. Black to Dead Car (Ground): Opens in new tabConnect the final black (-) clamp to an unpainted metal part of the dead car’s chassis or engine block, away from the battery. 

Disconnection Order (Disconnecting)
Remove the cables in the reverse order to prevent sparks: 

1. Remove Black from Dead Car .
2. Remove Black from Good Battery .
3. Remove Red from Good Battery .
4. Remove Red from Dead Battery .

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 connect black or red first?

When installing a new battery or reconnecting jumper cables, you should always connect the positive (red) terminal first and then the negative (black) terminal. The reasoning is that the negative terminal (black cable) is connected to the vehicle’s frame, and connecting it last prevents accidental sparks by ensuring the positive cable cannot complete a circuit to the frame when you’re handling it. Conversely, when disconnecting a battery, you should disconnect the negative (black) cable first and then the positive (red) cable.
 
Step-by-step connection (e.g., jump-starting or new battery installation):

1. Connect the red (positive) cable: to the positive terminal of the dead battery. 
2. Connect the other red (positive) cable: to the positive terminal of the donor car’s battery. 
3. Connect the black (negative) cable: to the negative terminal of the donor car’s battery. 
4. Connect the other black (negative) cable: to an unpainted metal part of the dead car that is not directly next to the battery, which serves as a good ground connection. 

Step-by-step disconnection:

1. Disconnect the black (negative) cable: from the unpainted metal part of the dead car. 
2. Disconnect the black (negative) cable: from the negative terminal of the donor car’s battery. 
3. Disconnect the red (positive) cable: from the positive terminal of the donor car’s battery. 
4. Disconnect the red (positive) cable: from the positive terminal of the dead battery. 

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.