How to Jump Start a Car: A Calm, Clear Guide From Someone Who’s Done It in the Rain

We’ve all been there. You hit the starter, the dash lights cough, and then… nothing. Don’t panic. Jump starting a car is simpler than it looks, and with the right order—and a little patience—you can be on your way in minutes. I’ve done it in grocery store lots, on frosty ski mornings, even outside a concert where the owner sheepishly admitted he’d listened to the encore with the headlights on. Here’s how to jump start a car safely and confidently.

What You’ll Need to Jump Start a Car

• Jumper cables (red for positive, black for negative), or a portable jump starter
• A second vehicle with a healthy 12V battery (or the aforementioned portable unit)
• Space to park nose-to-nose or side-by-side without cars touching
• Gloves and eye protection if you have them—batteries vent hydrogen gas

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

Modern cars may hide the battery under a cover, in the trunk, or beneath a seat. Look for the marked jump-start posts under the hood—usually red for positive (+) and a bare metal post for negative (–).

1. Both cars off. Keys out, lights off, accessories off. Park, apply parking brakes. Make sure the vehicles aren’t touching.
2. Find the terminals. Positive is “+” or red. Negative is “–” or black. On some cars (BMWs, Mercedes, many hybrids) use the designated jump posts under the hood.
3. Red to dead. Connect the red (+) clamp to the positive terminal on the dead battery.
4. Red to donor. Connect the other red clamp to the positive terminal on the good battery.
5. Black to donor. Connect the black (–) clamp to the negative terminal on the good battery.
6. Black to ground on the dead car. Clamp to a clean, unpainted metal point on the engine block or a solid chassis ground away from the battery. This helps avoid sparks near hydrogen gas.
7. Start the donor car. Let it idle for 2–5 minutes. If it’s a small car feeding a big SUV, give it a little throttle (1,500 rpm) to help.
8. Start the dead car. If it cranks weakly, wait another minute and try again. Still nothing after a few tries? Stop—something else may be wrong.
9. Remove cables in reverse order. Black from the grounded point, black from the donor battery, red from donor, red from the formerly dead battery. Keep clamps from touching anything metal as you remove them.
10. Let it run. Keep the revived car idling for at least 15–30 minutes or take a 20–30 minute drive to recharge.

Cheat Sheet: The Order to Jump Start a Car

• Connect: Red dead → Red donor → Black donor → Black ground (dead car)
• Disconnect: Black ground → Black donor → Red donor → Red dead

Common Mistakes When You Jump Start a Car (And How to Avoid Them)

• Clamps on the wrong terminals. Triple-check the + and – markings. Polarity errors can fry electronics. Don’t ask how I know.
• Bad ground point. If you clamp the last black lead to paint or plastic, no circuit. Find bare, solid metal.
• Cars touching. It’s a shortcut to short circuits. Keep a little distance.
• Revving like it’s 1999. A modest 1,500 rpm is fine. No need to redline the donor car.
• Instant shutdown after starting. Let the revived car run. Turning it off immediately might leave you stuck again.

Alternative: Jump Start a Car With a Portable Booster

These pocket-sized lithium packs are the unsung heroes of winter. I keep one in my long-term tester’s glovebox and it’s bailed me out twice this year alone.

After You Jump Start a Car: What Next?

• Drive it. A 20–30 minute highway run helps replenish the charge.
• Test the battery. If it’s more than 3–5 years old, have a shop load-test it. Many parts stores do this free.
• Check the alternator. If the battery dies again quickly, the alternator may not be charging. Look for a battery/charging warning light on the dash.
• Find the cause. Dome light left on? Glovebox not latched? Parasitic drains happen—especially in cars that sit.

When You Shouldn’t Jump Start a Car

• Cracked, bulging, or leaking battery. Hazmat territory—don’t mess with it.
• Hybrid/EV high-voltage systems. You can jump the 12V system of many hybrids, but never attempt to jump a high-voltage pack. Check the owner’s manual for the correct 12V jump points.
• Unknown aftermarket wiring. If the battery area looks like spaghetti, call a pro.

Real-World Moment

On a freezing January morning in Vermont, I tried to jump start a car that had sat for a month at a ski lodge—classic case. I followed the steps above, but the first attempt failed. The ground point was painted. Moved the clamp to a bare bolt on the strut tower, let the donor idle a bit longer, and it spun to life. Sometimes it’s the little things.

Conclusion: You Can Jump Start a Car Without Drama

Follow the order, respect the safety bits, and you’ll jump start a car like a pro. Keep a set of decent cables—or better yet, a portable jump starter—on board, and you’ll turn a potential day-ruiner into a minor pit stop.

FAQ: Jump Start a Car

• How long should I leave the cables connected before trying to start?
  Give it 2–5 minutes with the donor car idling. Big engines or deeply drained batteries may need a bit longer.
• Can I jump start a car in the rain?
  Yes. Batteries are low voltage. Just keep clamps off puddles and metal-to-metal contact to what’s intended.
• Which cable goes on first when I jump start a car?
  Red to the dead battery’s positive first, then red to donor positive, black to donor negative, and black to a ground on the dead car.
• Will jump starting damage my car?
  Not if you connect correctly. Reverse polarity or letting clamps touch can cause damage—double-check your connections.
• Can a bad alternator cause a dead battery?
  Absolutely. If the car dies again shortly after a jump, have the charging system tested.