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How to Jump Start a Car Safely, Step by Step

November 10, 2026

If a 12-volt battery is only discharged, you can often jump start a car with jumper cables and a running 12-volt vehicle, or with a portable jump pack. Connect the clamps in a set order, and put the last black clamp on an unpainted metal ground point so any spark stays away from the battery. Do not jump a cracked, leaking, bulging, or frozen battery. If you cannot work clear of traffic, call for help.

Before you begin

Inspect the dead battery first. AAA’s jump-start guidance says to skip the jump if the case is cracked or bulging, or if you smell rotten eggs, a sign of leaking acid and hydrogen gas that can ignite. A battery that may have frozen overnight can rupture when current is applied. Confirm both vehicles are 12-volt. Wear safety glasses, remove metal jewelry, and do not smoke. Use heavy-duty cables — AAA recommends 6-gauge, 16-foot cables, or a 4-gauge, 20-foot set when the cars cannot park tightly — or a jump pack rated for your engine. Leave the dead battery connected.

How to jump start a car with jumper cables

1. Park close, engines off

Park the cars close enough for the cables to reach, but do not let them touch. Set both parking brakes, shut both ignitions off, and put an automatic in Park or a manual in Neutral. Open both hoods and find the positive (+) and negative (−) terminals, or the marked remote jump posts.

Two cars parked close in a driveway with hoods open and engines off: a silver sedan and a dark-blue sedan, with no jumper cables connected yet.

2. Red clamp on the dead battery’s positive terminal

Hold the cables by the insulated handles and keep the metal clamps from touching each other. Clamp one red (positive) clamp to the positive (+) terminal of the dead battery, or the marked positive jump post.

A red jumper-cable clamp attached to the positive terminal of the silver car's dead battery, with the negative terminal still empty.

3. Red clamp on the working battery’s positive terminal

Clamp the other red clamp to the positive (+) terminal of the working vehicle’s battery.

A red jumper-cable clamp attached to the positive terminal of the dark-blue working car's battery, with the negative terminal still empty.

4. Black clamp on the working battery’s negative terminal

Clamp one black (negative) clamp to the negative (−) terminal of the working vehicle’s battery.

Red and black jumper-cable clamps on the working dark-blue car's battery: red on the positive terminal and black on the negative terminal.

5. Last black clamp on a ground point, not the dead battery’s negative post

Clamp the last black clamp to a clean, unpainted metal point on the car with the dead battery, such as a thick bolt on the engine block, away from the battery and the fuel system. Do not attach this clamp to the dead battery’s negative terminal. Route the cables so they cannot fall into belts or fans.

On the silver car with the dead battery, a red clamp is on the positive terminal and a black clamp is on an unpainted engine-block ground point, not on the battery's negative terminal.

6. Start the working car first

Start the working vehicle and let it run for three to five minutes so the discharged battery can take a surface charge.

A driver in the dark-blue working car turns the ignition key to start the engine, with the silver car visible through the windshield and its hood still open.

7. Start the disabled car

Try to start the disabled car. If it cranks slowly, wait a few more minutes and try again. After two or three unsuccessful attempts, stop.

A driver in the silver car turns the ignition key to start the previously dead engine, with the dark-blue working car visible through the windshield, hood open and headlights on.

8. Disconnect in reverse order, then drive

Let both engines run a few more minutes. Then remove the clamps in reverse order: black from the ground point, black from the working vehicle, red from the working vehicle, and finally red from the car you just started. AAA recommends a continuous 20- to 30-minute drive after that. If the car dies again soon, have the battery and alternator tested.

A gloved hand removes the black jumper-cable clamp from the unpainted engine-block ground point on the silver car first, while the red clamp remains on the positive battery terminal.

Jump packs, hybrids, and electric vehicles

A portable jump pack uses the same clamp idea, then you power the unit on. Follow the pack’s instructions for the black lead. Do not use a pack on a damaged or frozen battery. On a hybrid or EV, jump only the 12-volt auxiliary battery at the official posts in the owner’s manual. Never touch orange high-voltage cables, and do not use a hybrid or EV as the donor to jump another car.

Frequently asked questions

Is red positive or negative?

Red is positive; black is negative. The last black connection on the disabled car should be a ground point, unless the owner’s manual specifies a marked negative jump post.

Should the last black clamp go on the dead battery’s negative terminal?

No. AAA, VARTA, Jiffy Lube, and Ford place it on a clean, unpainted metal ground point, away from the battery.

How long should you wait, and how long should you drive after?

AAA recommends three to five minutes before the first start attempt, then a 20- to 30-minute continuous drive after the car starts.

Can you jump start a hybrid or an EV?

Often you can jump the 12-volt auxiliary battery only, at the official posts in the owner’s manual. Use a 12-volt source and never touch orange high-voltage cables.