The safest, most reliable way to jump‑start a car with jumper cables

The best method is: connect red clamp to the dead car’s positive (+) post, red clamp to the donor car’s positive (+), black clamp to the donor car’s negative (–), and the final black clamp to a clean, unpainted metal ground on the dead car—never its negative terminal. Run the donor for 2–5 minutes, start the dead car, then remove cables in reverse order. This approach minimizes sparks near the battery and protects electronics. Below is a detailed, up-to-date guide that reflects current recommendations from automakers and roadside-assistance organizations for modern 12‑volt systems, including vehicles with remote jump posts, start‑stop systems, and hybrids.

What you need and how to prepare

Before you start, assemble the right tools and set up a safe scene. Good cables and basic protection reduce risk to you and your vehicle’s electronics, especially on newer cars with sensitive battery-management systems. Park safely, set parking brakes, switch off accessories, and consult your owner’s manual to locate under‑hood jump posts (many cars place the battery in the trunk or under a seat).

• Quality jumper cables (4‑gauge or thicker, 10–20 ft long)
• Safety glasses and gloves
• Owner’s manual (for jump-post locations and any model‑specific steps)
• Wire brush or rag (to clear corrosion on terminals)
• Portable jump starter (optional, as a safer alternative to a donor vehicle)

With the right gear and a clear plan, you reduce the chance of arcing, overheating cables, or damaging a control module.

Connection order: step-by-step

Position and secure both vehicles

Park the donor vehicle close enough for the cables to reach without stretching, but ensure the vehicles do not touch. Put transmissions in Park (automatic) or Neutral (manual), set parking brakes, turn off lights and accessories, and open hoods. Identify the positive (+) and negative (–) terminals or the dedicated jump posts; check for cracks, leaks, or a swollen battery—if present, do not jump‑start.

Attach the cables in the correct sequence

Use this exact order to reduce the chance of sparks near the battery and to ensure a solid ground. Think: red‑dead, red‑donor, black‑donor, black‑ground.

1. Attach the red (+) clamp to the dead vehicle’s positive (+) battery terminal or designated positive jump post.
2. Attach the other red (+) clamp to the donor vehicle’s positive (+) terminal.
3. Attach the black (–) clamp to the donor vehicle’s negative (–) terminal.
4. Attach the final black (–) clamp to a clean, unpainted metal ground on the dead vehicle—an engine bracket, bolt on the block, or a labeled ground post. Do not use the dead battery’s negative terminal.
5. Confirm cables are clear of belts, fans, and hot parts, and the clamps aren’t touching each other or moving parts.

This sequence keeps any final connection—where a small spark is likeliest—away from the battery’s hydrogen gas, reducing explosion risk.

Start and charge

Start the donor vehicle and let it idle for 2–5 minutes; gently raise engine speed to around 1,500–2,000 rpm to help charging. Try starting the dead vehicle. If it doesn’t crank, wait another 2–3 minutes and try again. Avoid repeated long cranks—30 seconds on, a minute off—to prevent overheating the starter and cables.

Disconnect in reverse order

Remove the cables carefully in the exact reverse sequence to prevent arcing and accidental short circuits.

1. Remove the black (–) clamp from the dead vehicle’s ground point.
2. Remove the black (–) clamp from the donor vehicle’s negative (–) terminal.
3. Remove the red (+) clamp from the donor vehicle’s positive (+) terminal.
4. Remove the red (+) clamp from the formerly dead vehicle’s positive (+) terminal.

Reversing the order ensures you break the ground path first, which is the safest way to eliminate the circuit.

Aftercare: what to do next

Once the engine is running, your alternator must restore charge to the battery. The following steps help the battery recover and flag any underlying issues like a weak battery, failing alternator, or parasitic draw.

1. Keep the revived car running for at least 20–30 minutes; ideally take a steady drive rather than idling.
2. Limit heavy electrical loads at first (heated seats, rear defroster, high-beam lights) to ease alternator strain.
3. If the car stalls or won’t restart soon after, have the battery tested and charging system checked.
4. If you need frequent jump‑starts, investigate for alternator problems, loose/corroded connections, or a parasitic drain; batteries typically last 3–5 years.

A successful jump should be followed by a health check; recurring issues often point to a battery at end of life or a charging-system fault.

Troubleshooting and common mistakes

If the engine won’t start—or starts and immediately dies—these are the most likely culprits and quick checks you can do roadside.

• Dirty or loose terminals: Clean corrosion and tighten clamps; poor contact is a common no‑start cause.
• Wrong ground point: Move the black clamp to a better, bare-metal engine or chassis ground.
• Alarm/immobilizer: Lock and unlock the car with the remote; some systems block starts after low voltage.
• Severely discharged or damaged battery: Bulging, leaking, or frozen batteries should not be jump‑started—replace first.
• Blown fuse or relay: A starter, ignition, or main fuse can fail during a low‑voltage event; check the fuse box if accessible.
• Voltage mismatch: Do not mix 12‑volt and 24‑volt systems; confirm both vehicles are 12‑volt.
• Hidden jump posts: Many cars with trunk or under‑seat batteries require using under‑hood posts—consult the manual.

If multiple attempts fail, stop cranking to avoid damage. Consider a portable jump starter or professional assistance to prevent harming sensitive electronics.

Safety do’s and don’ts

These essentials reflect current best practices to minimize risk of fire, explosion, or electronic damage during a jump‑start.

• Confirm both vehicles use 12‑volt systems (most passenger vehicles); never jump a 12‑volt car from a 24‑volt truck.
• Wear eye protection; batteries can vent hydrogen gas and eject acid if compromised.
• Do not attach the final black clamp to the dead battery’s negative post; use a remote ground.
• Keep metal tools and jewelry away from terminals; avoid letting clamps touch.
• Set parking brakes; put transmissions in Park/Neutral; turn off accessories and lights.
• Do not smoke or create sparks near batteries.
• Use adequately thick cables (lower gauge numbers are better; 4‑gauge is a good all‑around choice).
• If cables or clamps get hot, stop and reassess connections.
• In freezing conditions, check for a frozen battery (ice crystals, bulging case); warm or replace rather than jump.

Sticking to these rules dramatically reduces the small but serious risks associated with boosting a vehicle.

Special cases: hybrids, EVs, start‑stop systems, and diesels

Hybrids and EVs

Hybrids and EVs also have 12‑volt auxiliary batteries that can die. Jump only via the designated 12‑volt posts shown in the owner’s manual; never touch high‑voltage components (orange cables/connectors). Many EV and hybrid makers allow jump‑starting another car from the vehicle’s 12‑volt system, but some advise against it to protect the DC‑DC converter—always check the manual before boosting another vehicle.

Start‑stop systems and AGM/EFB batteries

Cars with start‑stop typically use AGM or EFB batteries and may have battery sensors on the negative terminal. Use the under‑hood jump posts and the recommended ground point; avoid clamping on the sensor itself. The standard connection order still applies.

Large diesels and 24‑volt systems

Some heavy‑duty diesels and commercial vehicles use 24‑volt systems or dual batteries. Do not cross‑jump with a 12‑volt car. Use a compatible 24‑volt booster or follow the vehicle’s specific procedure.

Alternative: using a portable jump starter

A lithium jump pack can be safer and simpler than cables, with built‑in protections against reverse polarity and surges. Follow the device’s instructions alongside these general steps.

1. Verify the pack is sufficiently charged (typically 75%+), and rated for your engine size.
2. Power off the vehicle; connect red to the car’s positive (+) post, black to a chassis/engine ground.
3. Turn on the pack and wait for the “ready” indication (some packs pre‑check polarity/voltage).
4. Start the vehicle; disconnect clamps immediately after the engine runs.
5. Recharge the jump pack after use so it’s ready next time.

Jump packs reduce the need for a second vehicle and often provide safer, more controlled current for modern electronics.

Why the ground connection matters

Batteries can emit hydrogen gas during charging or heavy discharge; making the final connection away from the battery reduces the chance of igniting that gas. Grounding to the engine block or a designated stud also improves the quality of the return path for starter current and helps protect sensitive modules. This method remains the widely recommended practice among automakers, roadside services, and safety organizations.

Summary

To jump a car safely: connect red to the dead car’s +, red to donor +, black to donor –, and the final black to a clean ground on the dead car; run the donor for a few minutes, start the dead car, and remove cables in reverse order. Confirm both vehicles are 12‑volt, use proper cables, avoid sparks near the battery, and consult the owner’s manual for jump‑post locations. After a successful start, drive 20–30 minutes and test the battery and charging system if problems persist. A portable jump starter is a smart, safe backup for modern vehicles.

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.

In what order should I jump a car?

Connect the red clamp to the positive post on the dead battery. Connect the other red clamp to the positive post on the working battery. Connect the black clamp to the negative post on the working battery. Connect the last black clamp to an unpainted metal surface of your car.

What’s the best way to jump a car with jumper cables?

First we’ll hook our positive cable onto. The positive see the red cable mixed with the red. One. We’ll hook our negative cable onto the negative battery terminal.

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.