Should You Connect Jumper Cables Directly to the Battery?

Usually, you should not attach both jumper cable clamps directly to the dead battery. Connect the red (positive) clamp to the battery’s positive terminal or the vehicle’s designated positive jump post, and connect the black (negative) clamp to a solid, unpainted metal ground on the dead vehicle (or the manufacturer’s designated negative jump point)—not to the dead battery’s negative terminal. If the vehicle provides dedicated jump-start posts, use those instead of the battery.

Why the Negative Clamp Goes to a Ground, Not the Dead Battery Terminal

Attaching the negative clamp to an engine or chassis ground on the dead vehicle reduces the risk of sparks igniting hydrogen gas that can vent from batteries during charging. It also helps protect sensitive electronics and, on many modern cars, avoids bypassing an intelligent battery sensor on the negative terminal. Manufacturers frequently specify a remote negative post or a clean engine ground to ensure safer current paths and more reliable starts.

Use Manufacturer-Designated Jump-Start Points

Many vehicles—especially those with batteries in the trunk, under seats, or tightly packaged engine bays—provide labeled under-hood jump posts. These are the preferred connection locations and are engineered for safe current flow and proper sensor operation. Always check your owner’s manual first: if jump posts exist, use them instead of clamping directly to the battery.

Step-by-Step: How to Jump a Car Safely

The following sequence minimizes risk of sparks, protects electronics, and maximizes the chance of a successful start. Read your vehicle manuals first and follow any model-specific steps or warnings.

1. Park the vehicles nose-to-nose (without touching), set parking brakes, switch off all accessories, and put transmissions in Park/Neutral.
2. Verify both systems are 12-volt lead-acid (most cars and light trucks). Do not jump frozen, swollen, cracked, or leaking batteries.
3. Locate the manufacturer’s positive (+) and negative (-) jump points. If none exist, use the battery terminals as directed below.
4. Connect the red (+) clamp to the dead vehicle’s positive terminal or positive jump post.
5. Connect the other red (+) clamp to the donor vehicle’s positive terminal or positive jump post.
6. Connect the black (-) clamp to the donor vehicle’s negative terminal or negative jump post.
7. Connect the remaining black (-) clamp to a clean, unpainted metal ground on the dead vehicle (engine block or a dedicated negative post), away from the battery and moving parts.
8. Start the donor vehicle and let it idle for 2–5 minutes to provide some charge to the dead battery.
9. Attempt to start the dead vehicle. If it doesn’t start, wait a few more minutes and try again. Avoid repeated rapid cranking.
10. Once the dead vehicle starts, disconnect in reverse order: black clamp from the dead vehicle’s ground, black from the donor, red from the donor, red from the previously dead vehicle.
11. Keep the revived vehicle running for at least 20–30 minutes or drive to allow the charging system to replenish the battery. Consider testing the battery and charging system soon after.

Following this order reduces spark hazards and protects charging system components. If the vehicle will not start after several attempts, seek diagnostics rather than continuing to crank, which may damage the starter or electronics.

Common Mistakes to Avoid

These pitfalls can damage components or create safety risks. Review them before you connect anything.

• Clamping the negative cable to the dead battery’s negative terminal (instead of a ground or designated negative post).
• Reversing polarity (mixing up positive and negative) even momentarily—this can fry electronics and fuses.
• Letting metal clamps touch each other while one or more ends are connected.
• Jumping a frozen, swollen, cracked, or leaking battery.
• Attempting to boost an EV’s high-voltage traction battery (never do this); only the 12-volt system is jump-started via designated posts.

A quick double-check of polarity, ground location, and battery condition dramatically lowers risk and often determines success.

Special Cases and Cautions

Hybrids and EVs

Do not attempt to jump the high-voltage traction battery. Many hybrids and EVs have a conventional 12-volt battery or dedicated 12-volt jump posts—use only those as specified in the owner’s manual.

Vehicles with Battery Sensors (IBS)

If your car has an intelligent battery sensor on the negative terminal, use the designated negative jump point or an approved engine/chassis ground. Connecting to the wrong location can bypass the sensor and cause charging faults or error codes.

Start-Stop, AGM/EFB Batteries

AGM and EFB batteries can be jump-started using the same procedure, but using the manufacturer’s jump posts is especially important. If the battery is deeply discharged, a smart charger is often safer for the alternator than relying solely on a long post-jump drive.

Portable Jump Starters

Follow the pack’s instructions: connect red to the positive post/jump stud, black to the approved ground or negative jump post, and ensure the pack is rated for automotive 12-volt use.

Motorcycles and Small Powersports

Use a compatible 12-volt source or a motorcycle-rated jump pack. Avoid jump-starting from a running car, which can overvolt small systems.

After the Jump: What to Check

If the vehicle needed a jump, the battery may be weak or the charging system may be underperforming. A quick test should show charging voltage roughly in the 13.7–14.7 V range at idle (varies by vehicle and temperature). If lights dim, cranking is slow, or the battery is older than 3–5 years, consider a professional test or replacement.

Summary

Don’t connect both jumper clamps directly to the dead battery. Connect the positive clamp to the positive terminal or designated post, and connect the negative clamp to a solid engine/chassis ground or the manufacturer’s negative post on the dead vehicle. When available, always use the vehicle’s jump-start points, follow the correct connection/disconnection order, and avoid common mistakes to protect both vehicles and ensure a safe, successful jump.

Do I connect black or red first?

Always connect the red/positive terminal connector first, and just the opposite whenever you’re disconnecting the battery.

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.

Do you connect all cables directly to the battery when jumpstarting a car?

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.

What is the proper order to attach 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.