How to Jump-Start a Car

Battery dead? No roadside assistance? Learn how to jump-start your car in 10 easy steps.

By Tina Chang

Updated 24 March 2022

Sections on this page

What You Need
10 Steps to Jump-Start a Car: With Another Car
How to Jump-Start a Car Without Another Car
When You Shouldn't Jump Start a Car
Frequently Asked Questions

Whether you have a brand new car or a used car that's seen better days, you should know how to jump-start a car. You never know when your battery will die—maybe you left your lights on, or maybe your battery has just seen better days.

Although roadside assistance may be an option to get your car back on the road, jump starting your car yourself can save you a lot of time, money, and hassle. Follow our step-by-step guide to get yourself back on the road.

What You Need

When jumping a car, you're going to need the following things:

Your vehicle (that has the dead battery)
A second car (with a good battery)
Another person
Jumper cables

You may also want to keep these things in your car to make jump-starting it safer and easier:

Flashlight (in case you're jumping your vehicle at night)
Mechanic gloves (to prevent injuries)
Owner's manual

You'll also need a good battery—you don't want to jump a car with a damaged battery.

10 Steps to Jump-Start a Car: With Another Car

Before you jump-start your car, follow these steps to verify that it's safe to do so:

Read your owner's manual (it should be in your glove box) to make sure it's safe to jump-start your car. Look for warnings from the manufacturer.
Open the hood and check the battery. You don't want to jump-start a battery that looks damaged or frozen. (Read more on when you shouldn't jump a car below.)
Get to know the battery terminals. You'll notice both a positive and negative terminal.
Get to know the cables—there is a positive cable (red) and a negative cable (black).

Important Safety Information!

Don't allow any of the clamps on the jumper cables to touch each other once you've started hooking up your car. One person should hold the clamps on one end only—one in each hand.

Follow these steps to jump-start your car:

Park both vehicles so the jumper cables will reach.
Turn both cars off, put on the parking brakes, and open the hoods of both vehicles.
Securely connect the RED (positive) clamp of the jumper cable to your dead car's RED (positive) terminal post. You'll need to remove the plastic covering from the battery, so the clamp goes on the metal part.
Take the other end of the RED (positive) jumper cable and securely attach it to the RED (positive) terminal post of the working battery in the other car.
Securely attach the BLACK (negative) clamp of the jumper cable on the same end to the negative terminal of the good battery in the same car.
Attach the BLACK (negative) clamp on the other end to an unpainted metal surface on the main engine block of your dead car. This could be a metal bolt or nut. Try to attach it as far away from the battery as possible. Make sure the connections are secure.
Start the working vehicle with the cables connected and let it run for a few minutes.
Try to start your dead car. If it doesn't start, wait a little longer to give the working car time to charge the dead car's battery.
Once you've jump-started the car, let it run for a few minutes while still hooked up to the other vehicle to let it charge more.
Unhook the clamps when you're ready to go, in this order (reverse order that you put them on):
- BLACK (negative) clamp attached to the metal surface (bolt or nut).
- BLACK (negative) clamp attached to the working battery in the other car.
- RED (positive) clamp attached to the working battery.
- RED (positive) clamp attached to your previously dead battery.

And you're off! You'll want to drive your car for at least half an hour before turning it off to ensure your battery is sufficiently charged. If you turn it off too early, you might need to jump-start it again next time.

How to Jump-Start a Car Without Another Car

It may be impossible or difficult to find someone willing to offer their working car to you when your battery is dead. It may even be unsafe to flag a stranger down to help you in some cases.

If you're concerned about this, you may want to invest in a portable power source/jump starter. It serves as the doner battery, allowing you to charge your battery without needing a second vehicle.

These boxes will average around $150 and can be used for years. Buy them on Amazon or at any auto parts and accessories store.

How to Jump-Start a Car with a Portable Jump Starter

Before jumping your car's dead battery, read the owner's manual and look up your battery charger's voltage. You want to make sure it matches the jump starter's voltage (usually 12 volts).

Important Safety Notice

Do not allow the clamps on the portable charger's jumper cables to touch each other.

Make sure both the car and jump starter are off.
Securely connect the RED (positive) clamp to the positive terminal on your dead car battery.
Securely connect the BLACK (negative) clamp to an unpainted metal surface of your car (either on the engine itself or the car's frame). Try to find a bolt or nut somewhere far away from the battery, fuel lines, and carburetor.
Turn on the portable starter with the cables connected.
Try to turn on your car. Only crank it for about 5 seconds at a time.
If the car doesn't start, wait about 2 or 3 minutes, then try again. If your car still doesn't start after trying 4-5 times, you may need to replace your battery.
If your car starts, you can turn the jump starter off.
Remove the BLACK (negative) clamp from your car.
Remove the RED (positive) clamp from your car battery.
Let your car run for a few minutes before you start driving to allow your battery to charge itself.

After using your portable jump starter, you need to recharge it. Read the starter's manual for more information on how long it should charge for.

When You Shouldn't Jump Start a Car

Even though now you know how to jump start a car, sometimes it's not an option or can be dangerous. You shouldn't try to jump-start it if:

Your battery is frozen
Your car battery is leaking or cracked
Your battery is dry (there is no fluid in the cells)
You notice white or greenish power on the battery (it means the battery is corroded)
Your car manual warns against jump-starting the battery
Your jumper cables are old and/or damaged
You can smell a rotten egg smell from the battery (usually means a damaged battery)

Corroded car battery. — Don't try to jump start your car if you notice signs of corrosion or damage on your battery.

It's important to note that it can be risky to jump-start modern cars, as a surge in power can damage your vehicle's computer. A damaged computer can be much more costly than getting a new battery or paying for roadside assistance, so it's probably a job for the car experts if you're unsure what to do.

Frequently Asked Questions

Why would I need to jump start a car?

The main reason for jump starting your car is because of a weak or dead battery. This can happen for a variety of reasons, such as:

An old battery
Leaving your lights on when your car was off
Cold weather

Some other less common reasons include:

Issues with the starter or alternator
Clogged fuel lines
Dirty spark plugs

Can you jump start a car without cables?

You can jump start a manual car without jumper cables and without another car. You'll need your car to be on an incline.

Hold down the clutch and get the car into second gear without starting the vehicle.
Put the key into the ignition (don't try to start the car just yet).
Push the car down the hill.
Hold the clutch until your car is going about 5 miles an hour.
Release the clutch—the car should start.

If you aren't conveniently situated on a hill, you can still jump start your manual car without cables, but you'll need much more help pushing the car.

How can I tell if my car battery is dead?

There are a few signs of a dead battery to look for:

Your car doesn't start when turning on the ignition.
Your car starts but then dies right away.
The motor cranks but the engine won't start.
The engine takes longer to crank.
The "Check Engine" light is on.
Your door lights don't turn on, even though they're switched on.
Your headlights don't work.
Your battery looks damaged, corroded, or swollen.
You can smell rotten eggs from your battery.

What if my car still doesn't turn on?

If you've tried to jump start your car but you still have a dead battery, this either means you need a completely new battery or there is some other reason your car isn't starting. If you don't know that much about cars, your best option is to get professional help from a mechanic.