How to Jump a Car: A Complete Step-by-Step Guide

Knowing how to jump a car can save you an hour and a tow bill. All you need is a set of jumper cables, a working vehicle (or a portable jump starter), and five to ten minutes.

A dead battery is one of the most common roadside problems in the U.S. It usually isn't complicated to fix. But get the cable order wrong, and you risk a spark, a blown fuse, or damage to a car's electronics.

This guide walks through the exact steps, the right connection order, and what to do if the jump doesn't work. We'll also cover EVs, hybrids, and when you should just call for help instead.

What You Need Before You Jump a Car

First, make sure you actually have jumper cables or a portable jump starter in the trunk. Then check a few things before you touch any clamps.

• A set of jumper cables at least 10 feet long (16 feet if the dead car's battery is hard to reach)
• A working vehicle with a healthy battery, or a portable lithium jump starter pack
• Both cars in park or neutral, parking brakes on, engines off until instructed
• Safety glasses if you have them — battery acid can splash during a bad connection

Park the working car close enough that the cables reach, but don't let the vehicles touch. Metal-to-metal contact between the cars can cause electrical issues.

How to Jump a Car With Jumper Cables (Step by Step)

The connection order matters more than anything else here. Doing it out of order is the single biggest cause of sparks and damage.

1. Turn off both engines and put both vehicles in park with the parking brake set.
2. Locate both batteries. Most sit under the hood, but some cars (many BMWs, some Mercedes models) have the battery in the trunk with a jump-start terminal under the hood instead.
3. Connect the red (positive) clamp to the positive terminal on the dead battery. It's marked with a plus sign and is usually larger than the negative post.
4. Connect the other red clamp to the positive terminal on the good battery.
5. Connect the black (negative) clamp to the negative terminal on the good battery.
6. Connect the final black clamp to an unpainted metal surface on the dead car's engine block or frame — not the dead battery's negative terminal. This grounds the circuit and cuts down on sparking near the battery.
7. Start the working car and let it run for about 2-3 minutes.
8. Try starting the dead car. If it turns over, let it idle for a few minutes before removing cables.
9. Remove the cables in reverse order: ground clamp first, then the good battery's negative, then both positive clamps.

Warning: Never let the red and black clamps touch each other while any clamp is connected to a battery. That creates a direct short and can send sparks flying.

Which Car Should You Connect the Cables To First?

Always start with the dead battery's positive terminal, then move to the working car's positive terminal. Here's why the order matters:

Connecting the ground (negative) clamp last — and attaching it to bare metal, not the battery — keeps any spark away from the battery itself. Batteries release hydrogen gas, and a spark near the terminal can, in rare cases, ignite it.

If you're unsure which post is positive, look for the plus (+) sign or red cover. Most terminals are also color-coded or labeled directly on the battery case.

How to Jump a Car With a Portable Jump Starter

A portable jump starter skips the need for a second car entirely. These battery packs run $40-$150 and fit in a glove box.

1. Make sure the jump starter is charged. Most show a battery level on a small screen or LED.
2. Connect the red clamp to the dead battery's positive terminal.
3. Connect the black clamp to an unpainted metal surface, away from the battery.
4. Turn on the jump starter (many have a power button or auto-detect the connection).
5. Start the car. It should turn over within a few seconds.
6. Disconnect the clamps and turn off the jump starter to save its charge.

Portable units are worth owning if you drive an older car or live somewhere with cold winters — cold weather is the top reason batteries die. For a deeper cost breakdown of professional jump-start calls versus doing it yourself, see How Much Does a Jump Start Cost? Complete Pricing Breakdown.

What If the Car Won't Start After Jumping?

If the engine doesn't turn over after a few tries, don't keep cranking it. That can drain the good battery too and strain the starter motor.

• Check your connections. A loose clamp is the most common reason a jump fails.
• Let it charge longer. Give the dead battery 5-10 minutes connected before trying again.
• Listen for clicking. A single click usually means the battery is too far gone or the starter itself has failed.
• Check for corrosion. White or greenish buildup on terminals blocks the connection — a wire brush can clear it in seconds.

If the car still won't start, the battery may be fully dead, or the real problem could be the alternator, starter, or a parasitic drain. At that point, it's time to call a tow truck or mobile mechanic rather than keep trying. Our guide on How Long to Run Car After Jump Start? The Real Answer explains why a quick idle isn't always enough to fully recharge the battery.

How to Jump an EV or Hybrid (Special Cases)

Hybrids and EVs usually still have a small 12-volt battery that runs the electronics and starts the system, separate from the main traction battery. You can jump this 12-volt battery the same way as a regular car, but check your owner's manual first.

Some hybrids have a dedicated jump-start terminal instead of direct battery access, since the main battery sits in the trunk or under the back seat. Never try to jump the high-voltage traction battery yourself — that's a job for trained technicians only.

For more on handling these vehicles safely, see our Hybrid Vehicle Towing Guide: Dual System Considerations Explained and EV Towing Challenges: What to Know About Battery Risks.

Common Mistakes That Damage Your Battery or Electronics

A bad jump can cost more than the battery itself. Here are the mistakes that cause real damage:

• Reversing polarity — connecting positive to negative. This can blow fuses or fry a car's computer in seconds.
• Connecting the final clamp to the dead battery instead of bare metal, which risks sparking near battery gas.
• Jumping a frozen or physically damaged battery. A cracked or leaking case can be dangerous to jump at all.
• Letting the vehicles touch. This can create an unintended ground path and electrical noise.
• Revving the working car's engine during the jump. It doesn't speed things up and can spike voltage.

How Long Should You Drive After a Jump Start?

Plan on driving at least 15-30 minutes, or more if your battery was fully dead. A short idle in the driveway rarely puts enough charge back in.

So how do you know it actually took? If the car starts again on its own after sitting a few hours, the battery is holding a charge. If it dies again quickly, the battery likely needs replacing — or something else is draining it while parked.

When to Call a Professional Instead of Jumping It Yourself

Jumping a car yourself is usually safe, but it's not always the right call. Here's a simple way to decide:

A mobile jump-start service call typically runs $35 to $95, depending on your location and time of day. Prices from providers can run higher overnight or in rural areas. Prices are current as of 2026 and vary by region — we're not affiliated with any specific provider.

If you don't already have a plan in place, our Best Roadside Assistance: Complete 2026 Guide compares coverage options. And if the jump doesn't work and your car needs a real tow, you can find towing services near you through USA Tow Finder in minutes.

Keep a set of cables or a jump starter in your trunk year-round. A dead battery always seems to happen at the worst possible time — but with the right steps, you can usually be back on the road in under 10 minutes. If not, get a free towing quote and get help on the way fast.