EveryManSkills
Car and Road

How to jump start a car with a jump pack

To jump start a car with a portable jump pack, switch everything off, check the battery is not cracked or leaking, clip the red clamp to the positive post and the black clamp to bare engine metal or the negative post as the pack's manual says, then switch the pack on and start the car. Remove the clamps in reverse, black first, and let the engine run for 20 to 30 minutes.

Jump pack or cables?

A jump pack is a battery in a box with its own short clamps. It does the job of a second car, so you can start yours alone in a parking lot at night. Most packs also refuse to switch on if the clamps are reversed, which removes the most dangerous mistake. Cables are cheaper and never run flat, but they need a helper car and the four-clamp order in the cable guide. The safe order is the same idea in both cases: positive first, the last connection away from the battery, and removal in reverse.

Step by step

  1. Check that the jump pack is charged and read its manual and your car's owner's manual for the jump points.
  2. Turn off the car, the headlights, the radio and every accessory, and put the car in park or neutral with the brake on.
  3. Look at the battery and stop if its case is cracked, leaking, bulging or frozen.
  4. With the pack switched off, clip the red clamp to the battery's positive post.
  5. Clip the black clamp to a bare, unpainted metal bolt on the engine, or to the negative post if the pack's manual says so.
  6. Switch the pack on, wait for its ready light, and start the car.
  7. If the car does not start within a few seconds, stop and wait as long as the pack's manual says before trying again.
  8. Once the engine runs, switch the pack off and remove the black clamp first, then the red, and keep the engine running for 20 to 30 minutes.
  9. Recharge the pack the same day so it is ready next time.

The drawing shows the cable version: the same red-to-positive start and the same final connection on bare metal, clear of the battery.

Jump start clamp orderTwo batteries side by side. Clamp 1, red, goes on the dead battery's positive terminal. Clamp 2, red, goes on the good battery's positive terminal. Clamp 3, black, goes on the good battery's negative terminal. Clamp 4, black, goes on bare unpainted metal on the dead car's engine, away from its battery. Remove them in reverse order, 4, 3, 2, 1.Dead carDead battery+−Engine block boltWorking carGood battery+−1234
Clamp order: 1 red on the dead battery's positive, 2 red on the good battery's positive, 3 black on the good battery's negative, 4 black on bare metal on the dead car, away from the battery. Remove in reverse.

A worked example: alone in a parking lot

You come back to your car after a late shift and the engine only clicks. The dash lights are dim, which points to a flat battery rather than a starter fault. You take the jump pack from the trunk and see three of its four charge lights lit. With the car off and the key out, you open the hood, find the battery and see no cracks or leaks. Red clamp on the positive post, marked with a plus sign; black clamp on a bare bolt on the engine block. You switch the pack on, wait for the green light, and the car starts on the first try. Pack off, black clamp off, red clamp off, hood closed. You drive home the long way, about twenty-five minutes, and put the pack on charge overnight. If the car will not start again two days later, the battery is the likely problem, so have it tested.

Common mistakes

When to stop and call for help

Stop if the battery is damaged, if you smell rotten eggs or see smoke, if the car still will not start after the tries the manual allows, or if the car is a hybrid or electric model whose manual rules out jumping. Call roadside assistance instead. The warning light guide helps if a battery light stays on after the start, and the emergency kit guide lists what else belongs in the trunk. For the whole picture, see car skills every man should know.

Sources

Last checked September 28, 2026. Everything here is in our own words. Where a professional who can see your situation, or current official guidance, says something different, follow them.

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Frequently asked questions

Is a jump pack better than jumper cables?

For most drivers, yes. A charged pack needs no second car, fits in the glove box or trunk, and most have reverse polarity protection. Cables still work when the pack is flat, so some people carry both.

Which clamp goes on first with a jump pack?

Red on the positive post first, then black on bare engine metal or on the negative post, with the pack switched off. Take them off in reverse: black first, then red.

How long should I let the car run after a jump?

Drive or idle for 20 to 30 minutes so the alternator can put some charge back. If the battery dies again within a few days, have the battery and charging system tested.

Can I jump a hybrid or electric car with a jump pack?

Only as the owner's manual allows. Many hybrids and electric cars have a small twelve-volt battery with separate jump points, and some should not be used to jump anything. Never touch the high-voltage system.