How to Jump Start a Car: Step by Step Guide With Jumper Cables or a Jump Starter

Connect the cables in this order: red to the dead battery, red to the good battery, black to the good battery, then black to bare metal on the dead car. Start the working car first, wait a few minutes, then try to start the car with the flat battery. Remove the cables in the reverse order once the car is running. Drive for at least 30 minutes afterward so the battery can recharge. Never jump start a battery that is cracked, leaking or frozen.

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It is one of the most common car problems of all. You turn the key or press the start button, and nothing happens, or the engine makes a slow clicking sound. A flat battery can strike at any time, but it happens most often on cold winter mornings.

Knowing how to jump start a car can save you time, money and the stress of waiting hours for roadside help. It takes about 10 minutes and just a set of jumper cables or a portable jump starter.

Here is how to jump start a car safely, step by step, plus what to do afterward and when a jump start will not work.

Signs Your Battery Is Dead

The first step in how to jump start a car is checking that the battery is the problem. Before you try to jump start a car, make sure the battery is really the problem. Common signs include:

• The engine turns over very slowly, or not at all
• A clicking sound when you try to start the car
• Dashboard lights are dim or do not come on
• Headlights are weak
• The car started fine yesterday but not after a cold night

If the lights and radio work normally but the engine still will not start, the problem could be the starter motor, fuel or something else.

What You Need

• Jumper cables (called jump leads in the UK), or a portable jump starter
• A second car with a working battery of the same voltage, usually 12 volts
• Safety glasses and gloves, if you have them
• Your owner’s manual, which may show special jump points

How to Jump Start a Car With Jumper Cables

This is the classic method and works with almost any vehicle.

Step 1: Position the Cars

The first practical step in how to jump start a car is getting the vehicles in place. Park the working car close to the car with the flat battery, so the cables can reach both batteries. The cars should not touch each other.

Turn off both engines, put both cars in Park or neutral with the parking brake on, and remove the keys.

Step 2: Turn Everything Off

Switch off headlights, the radio, heater, phone chargers and anything else that uses power in both cars.

Step 3: Find the Batteries and Terminals

Open both hoods and find the batteries. Some cars have the battery in the trunk or under a seat, with special jump points under the hood. Check your manual if you are not sure.

Each battery has two terminals:

• Positive (+): Usually marked with a plus sign and often a red cover
• Negative (minus): Marked with a minus sign and often black

If the terminals are covered in white or green crust, wipe them gently with a cloth while wearing gloves.

Step 4: Connect the Cables in the Right Order

This is the most important part of learning how to jump start a car. Follow this order exactly:

Order	Cable	Connect to
1	Red	Positive (+) terminal of the dead battery
2	Red (other end)	Positive (+) terminal of the good battery
3	Black	Negative (minus) terminal of the good battery
4	Black (other end)	Bare, unpainted metal on the dead car’s engine or a ground point, away from the battery

The last connection goes to metal rather than the dead battery’s negative terminal because a small spark can happen. Keeping that spark away from the battery reduces the risk of igniting any gas the battery may give off.

Make sure the cable clamps do not touch each other while any of them are connected.

Step 5: Start the Working Car

Start the car with the good battery and let it run for two to five minutes. Raising the engine speed slightly can help charge the flat battery.

Step 6: Start the Car With the Flat Battery

Now try to start the car with the dead battery. If it starts, great. If not, wait a few more minutes and try again.

If the car still does not start after a few tries, stop. There may be a bigger problem.

Step 7: Remove the Cables in Reverse Order

Once the car is running, remove the cables in the opposite order:

1. Black from the metal on the jumped car
2. Black from the good battery
3. Red from the good battery
4. Red from the jumped battery

Do not let the clamps touch each other or any metal while removing them.

Step 8: Keep the Engine Running

Drive the jumped car for at least 30 minutes, ideally on a longer road at steady speed, so the alternator can recharge the battery. Short trips may not put enough charge back in.

How to Jump Start a Car With a Portable Jump Starter

If you want to know how to jump start a car without help, this is the answer. A portable jump starter, sometimes called a jump pack or booster pack, lets you jump start a car without a second vehicle. Many are small enough to keep in the glove box.

1. Make sure the jump starter is charged.
2. Turn off the car and all electrical items.
3. Connect the red clamp to the positive (+) terminal.
4. Connect the black clamp to bare metal or the negative (minus) terminal, as the instructions say.
5. Switch on the jump starter.
6. Start the car.
7. Switch off the jump starter and remove the clamps, black first.

Jump starters cost from about $50 to $150 in the US, or £40 to £120 in the UK. They are a smart thing to keep in your car in winter, and many can also charge your phone.

Safety Tips

Safety matters every time you jump start a car.

• Never jump a battery that is cracked, leaking or bulging.
• Do not jump a frozen battery. If you see ice or the sides are swollen, it could explode. Let it thaw first.
• Keep sparks and flames away. Do not smoke near a battery.
• Wear eye protection if you can.
• Check the voltage. Both cars should use the same voltage battery, usually 12 volts.
• Read your manual. Some modern cars, hybrids and luxury models have special instructions.

Can You Jump Start an Electric or Hybrid Car?

Electric and hybrid cars have a large high voltage battery for driving, but they also have a normal 12 volt battery that powers the computers and lights. If the 12 volt battery dies, the car will not switch on.

Many EVs and hybrids can be jump started using the 12 volt battery or special jump points, but the process varies. Some manufacturers say their electric cars should not be used to jump start another vehicle. Always check the owner’s manual first.

Why Do Car Batteries Die?

Cause	What happens
Cold weather	Batteries produce less power in the cold
Old age	Most batteries last about three to five years
Lights left on	Interior or headlights drain the battery overnight
Short trips	The battery never fully recharges
Car not used	Batteries slowly lose charge when parked for weeks
Faulty alternator	The battery is not recharged while driving
Corroded terminals	A poor connection stops power flowing

How to Jump Start a Car Alone

If no one is around to help, you have a few options:

• Use a portable jump starter. This is the easiest way to jump start a car on your own.
• Ask a passing driver or neighbor if they can help with jumper cables.
• Call roadside assistance. Many car insurance policies, credit cards and new car warranties include it.
• Push start a manual car. Some older cars with a manual gearbox can be started by rolling them in second gear and releasing the clutch, but this does not work with automatics and is not recommended for modern cars.

Choosing Jumper Cables

Not all jumper cables are the same. When you buy a set, look for:

• Thicker wire. A lower gauge number, such as 4 or 6 gauge, means thicker cables that carry more power.
• Length of at least 12 to 20 feet, so they reach between cars easily.
• Strong, well insulated clamps with a firm grip.

Keep them in your trunk all year, along with gloves and a flashlight.

What to Do After a Jump Start

A jump start gets you going, but it does not fix the cause. After you jump start a car:

1. Drive for at least 30 minutes.
2. Get the battery tested. Many auto parts stores and garages test batteries for free.
3. Check the age of the battery. If it is more than three to five years old, it may be time to replace it.
4. Watch for warning lights. A battery light on the dashboard while driving can mean an alternator problem.
5. If it goes flat again soon, have a mechanic check the battery, alternator and charging system.

When a Jump Start Will Not Work

If the car still will not start, the problem may be:

• A battery that is completely worn out
• A faulty starter motor
• A broken alternator
• Loose or damaged battery cables
• An empty fuel tank
• A blown fuse

In that case, call roadside assistance or a mechanic. In the US, AAA and many insurance policies include roadside help. In the UK, the AA and RAC offer breakdown cover.

Keep Your Battery Healthy

The best way to avoid needing to know how to jump start a car is to look after your battery.

• Test your battery every winter, especially once it is three years old.
• Turn off lights and accessories when you park.
• Take a longer drive at least once a week.
• Keep the terminals clean.
• Use a battery maintainer if your car sits unused for a long time.

Our guide to winterizing your car has more tips for cold weather. The National Highway Traffic Safety Administration also shares vehicle safety advice at NHTSA.gov. For more background, see the jump start Wikipedia page.

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Frequently Asked Questions

Sources: AAA, RAC, AA, NHTSA, battery manufacturer guides