How to Jump Start a Car: Cable Order and Jump Packs

With cables, it comes down to order: park the good car close, turn both cars off, then clamp red to the dead battery’s positive, red to the good battery’s positive, black to the good battery’s negative, and the last black clamp to bare metal on the dead car’s engine, away from the battery. Start the good car, wait a few minutes, then start the dead one. Check your owner’s manual first, because some cars have a dedicated jump point or special rules.

Quick version

• Order on: red dead, red good, black good, black to bare metal on the dead car.
• Run the good car 3 to 5 minutes before you try the dead one.
• Remove the cables in the exact reverse order.
• Drive 20 to 30 minutes afterward so the battery can recharge.
• Hybrids and EVs: follow the owner’s manual, or call roadside help.

Before you touch a cable

• Read the owner’s manual section on jump starting. Consumer Reports’ chief mechanic says manuals spell out the exact steps for your car, and ChrisFix notes that some cars have a ground point set aside for jumping, which the manual will show.
• Look at the dead battery. AAA says to replace, not jump, a battery that is cracked, bulging or leaking. A strong rotten-egg smell means leaking acid and hydrogen gas, so don’t jump that battery; call for help.
• Confirm both systems are 12-volt. Some commercial trucks run 24 volts and can damage a normal car.
• Take off metal jewelry and wear glasses and gloves if you have them.
• Don’t do this on a busy highway or in poor visibility. Call for roadside help instead.

How to jump start a car with jumper cables

1. Position the cars. Park the working car close enough for the cables to reach, with a few inches between the cars. They should not touch. Both in park (or neutral for a manual) with the parking brake set.
2. Turn both cars fully off and take the keys out.
3. Find positive and negative on each battery. Positive is marked ”+” and usually has a red cover. Negative is ”-” and black.
4. Untangle the cables and hold one end in each hand. From here on, the metal clamps on the same end must never touch each other.
5. Red clamp to the dead battery’s positive terminal. Wiggle it so it bites onto the metal post.
6. Other red clamp to the good battery’s positive terminal.
7. Black clamp to the good battery’s negative terminal.
8. Last black clamp to bare, unpainted metal on the dead car, such as a thick bolt on the engine block or the strut tower, away from the battery. This last connection can spark, and a run-down battery can give off hydrogen gas. Keep it clear of the fuel system and any moving parts.
9. Check the cables aren’t near the cooling fan or belts on either car.
10. Start the good car and let it run for 3 to 5 minutes.
11. Start the dead car. If it cranks slowly but doesn’t catch, wait about five more minutes and try again. AAA says if it won’t start by the third try, the battery is likely done.
12. Disconnect in reverse order: black from the ground point, black from the good battery, red from the good battery, red from the car you just started. Don’t let the clamps touch each other or any metal while they’re live.
13. Drive for 20 to 30 minutes without stopping, A/C and rear defroster off. Get the battery tested if it’s more than three years old.

If it still won’t start

A slow crank means the jump is working but needs more time; give it five more minutes connected. A single click with no crank, or nothing at all, points somewhere else:

• Check every clamp. Before giving up, ChrisFix rechecks the connections at both batteries. Squeeze each clamp and wiggle it onto clean metal.
• Move the ground clamp. He says switching to a better ground often gets the car going. Paint and thin brackets carry current poorly; try a thick bolt on the engine block.
• Think about the battery’s age. ChrisFix puts the average battery life at about four years. An old battery with a dead cell won’t hold a jump, and AAA’s rule is that three failed tries means it’s time for a replacement.
• Consider other causes. Lights on the dash but no crank at all can mean a starter or connection problem, which a jump won’t fix. That’s a tow or a mechanic.

No second car: the jump pack

A jump pack is a battery in a box with its own short clamps. You don’t need a second car.

1. Make sure the jump pack is off and charged.
2. Clamp red to the dead battery’s positive terminal.
3. Clamp black to the negative terminal or a bare-metal ground, whichever your pack’s manual says. Packs with an on/off switch don’t send power until you switch them on, which is why ChrisFix connects his straight to the battery’s negative.
4. Switch the pack on.
5. Start the car.
6. Switch the pack off, then remove black, then red.
7. Recharge the pack when you get home.

Cables or a portable jump starter?

If you live somewhere with hard winters, keep cables even if you buy a pack. If you drive alone a lot, the pack is worth it, because a dead battery at 11 p.m. in an empty lot is exactly when nobody is around to give you a jump. When you shop, match peak amps to your engine: Consumer Reports’ buying guide, citing the jump starter maker Lectron, suggests roughly 800 to 1,200 peak amps for engines of 2.0 liters or less and more for bigger engines and diesels.

Want the rest of your trunk kit sorted? Our guide on how to change a tire covers the spare and jack. If you’re stocking a new place too, the first apartment checklist lists what to buy now and what can wait.

What the pros say

• ChrisFix, Chris Gallagher’s car repair channel, explains why the red clamp goes on the dead battery first and why the final black clamp goes on a ground away from the battery: the spark from that last connection can ignite hydrogen gas from a run-down battery. If the car won’t start after a few minutes, he suggests waiting five more minutes, having the helper hold the good car at about 2,000 rpm, and moving the ground clamp to a better spot.
• Rob Kenney, creator of Dad, how do I?, sums up the order in his video notes as “Red Dead, Red Good, Black Good, Black Ground (dead),” which is the easiest version to remember in a dark parking lot.
• Scotty Kilmer, a mechanic and car advice host, shows a small lithium jump pack starting a V8 truck with a fully dead battery, and points out that packs with a power button and a warning light won’t send power if you hook them up backward.
• John Ibbotson, Consumer Reports’ chief mechanic, tells drivers to follow the owner’s manual closely and, if in doubt, to get help. The same article suggests keeping a portable jump starter in the car and checking its charge from time to time.

Gear that helps

We researched these picks against AAA’s and Consumer Reports’ guidance and the makers’ specs; we haven’t tested each one ourselves.

Do this this week

• Open your owner’s manual and find the jump-start page and any dedicated ground point.
• Pop the hood in daylight and locate the battery’s positive and negative terminals.
• Pick a bare-metal ground spot on your engine now, so you aren’t hunting at night.
• Put cables or a charged jump pack in the trunk.
• Set a phone reminder to recharge the jump pack every three months.
• If your battery is over three years old, get it tested at an auto parts store.