EveryManKnows
Car and Road

How to jump start a car

To jump start a car, connect the cables in a fixed order: red on the flat battery's positive post, red on the helper battery's positive, black on the helper's negative, and the final black on bare engine metal of the stalled car, clear of its battery. Then start the working car, wait a few minutes, and start yours. Take the clamps off in reverse order.

About 15 minutes to learnTake care: injury or damage if careless

Mark it once you can do it without this page open.

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.

How to do it

  1. Nose the helper car in close, leave a gap between the bumpers, and turn off both ignitions, headlights and radios.
  2. Read both owner's manuals first, since some hybrids and electric cars use separate jump posts or rule out jumping.
  3. Inspect the flat battery, and walk away from the job if its case is cracked, leaking, bulging or frozen.
  4. Clip one red clamp to the flat battery's positive post, then the other red clamp to the helper battery's positive post.
  5. Clip one black clamp to the helper battery's negative post.
  6. Clip the last black clamp to a bare, unpainted bolt or bracket on the stalled car's engine, well clear of its battery.
  7. Run the helper car for three to five minutes, then try the stalled car.
  8. Take the clamps off in the opposite order, never letting two metal ends meet, then drive for 20 to 30 minutes.

Stop and call a professional if

  • The battery is cracked, leaking, swollen, frozen or smells of rotten eggs.
  • The car still will not start after two or three tries with good connections.
  • The car is a hybrid or electric vehicle and the manual does not show a jump procedure.
  • The battery keeps dying, which points to a charging fault or a drain a shop needs to find.

Common mistakes

  • Connecting the last black clamp straight to the dead battery's negative post, which can spark right where battery gas collects.
  • Letting the red and black clamps touch while any end is connected.
  • Switching the car off at the first stop, before the battery has had any time to recharge.

Quick self-check

Three questions. Your last score is kept in this browser.

1. Where does the final black clamp go?
2. Which connection comes first?
3. The dead battery case is cracked and damp. What do you do?

Teach this to someone

A one-page sheet for showing a friend, a roommate or a kid: what to say, what to show, and one question to check it landed.

Sources

  • Your vehicle's owner's manual, for your model year. Checked September 28, 2026.

Last reviewed . First published .