How to Jump Start a Car: 5 Steps

A jump start can get you moving again when your battery is flat. If you need to know how to jump start a car, this post covers the steps, the order to complete them, and the essential safety tips you’ll need. 

If you don’t feel comfortable following the steps in this post, it’s best to contact a mechanic or use your breakdown cover. For example, if you’re not sure that your battery is the problem, or you can’t confidently identify the parts of your engine, it’s best to leave jump starts to the pros. Unfortunately, it’s all too easy to injure yourself or damage your engine if you make a mistake. 

What equipment do you need to jump start a car?

A jump start can be a relatively straightforward process, but it needs some special equipment. Before you start, find: 

• A pair of jump leads. Jump leads are cables between about 3m and 6m in length (for a car, the shorter lengths will usually reach far enough). They come in pairs, one red positive lead and one black negative lead, and they have crocodile clips at each end to connect to the terminals on the batteries. 

• Another car with a fully charged battery. The car with the working battery should have the same voltage as yours. For example, if you have a 12v battery in your vehicle, you need to jump it with another 12v battery.

• A pair of rubber work gloves and goggles. These will protect your hands and eyes as you work. 

Once you have all this equipment in place, you can start the process of jump starting your car. 

What are the 5 steps to jump start a car? 

Step 1: Safety first

Before you start, make sure that you’re in a safe area.

You should check yourself, too. Take off any dangling clothing like ties, scarves, or long necklaces. This can prevent accidents when parts of the engine start to move. If you’re wearing any metal – rings, watch straps, etc. – you should also remove it. If the metal touches the battery, it can cause sparks.

You should also consult your owner’s manual, as there might be information specific to your car’s engine that can help during the next stages.

Finally, check that your equipment is safe to use. Inspect the jump leads to make sure they’re not worn or damaged, and check that the battery itself isn’t broken or leaking.

Step 2: Get into position

To successfully jump start a car, you’ll need another car with a working battery. Park the working vehicle close enough that the leads can reach between the batteries, but not so close that the cars touch.

Then, check that both cars have the handbrake on. You’ll also need to turn off the engines and any other electrical systems, such as the sat-nav, lights, and radio.

If you can, it’s also best to roll down the driver’s window before you start.  Many people have locked their keys in the car while they’re doing a jump start, and rolling down the window will help to stop you from becoming one of them.

Step 3: Connect the jump leads

Asking yourself ‘What’s the correct order to jump start a car battery?’ Or ‘When jump starting a car, which cable goes on first?’ This step is for you.

Once the cars are prepared, it’s time to connect the leads. Find the positive and negative terminals on each battery. The positive (+) terminal usually has a red cover. If you pull that cover back, you’ll be able to access the terminal.

The first step is to connect the positive terminals of the batteries with the red lead. Start by clipping one end of the lead to the positive terminal on the car with the flat battery (the rhyme “red to dead” can help you remember where to start). Then, clip the other end to the positive terminal of the working battery.

Then, take the black lead. Connect one end to the negative (-) terminal on the working battery. The other end should be connected to an ‘earthing point’ on the car with the flat battery. This can be any solid, unpainted metal on the engine or chassis, as long as it’s a safe distance from the battery and fuel system. Some cars have an earthing rod to make this step easier. Check the owner’s manual to find out if yours does.

Still wondering how to do jump leads? Let’s recap the order:

• The red  jump lead connects to the positive (+) terminal on the flat battery.
• The red jump lead connects to the positive (+) terminal on the working battery.
• The black jump lead connects to the negative (-) terminal of the working battery.
• The black jump lead connects to an earthing point on the car.

Try to remember this order, as you’ll have to do it in reverse later. It’s also extremely important that you don’t let the ends of the red and black leads touch, as this can cause sparks and damage the engine.

While the batteries are connected, the jump leads send power from the working battery to the flat one. This charges the battery enough that the engine can start, and it will then recharge fully during normal driving. Waiting about 3 minutes before starting the engines is important for this initial charge.

Step 4: Start the cars

After you’ve waited for those first three minutes, start the working car’s engine and let it idle. Then, after another minute, try to start the engine of the car with the flat battery. If it switches on, keep both cars idling for about 10 minutes.

If the broken-down car won’t start at this point, it’s best to call a mechanic or roadside assistance to find out what’s really going on with your engine.

Step 5: Turn off the cars and disconnect the leads

After both cars’ engines have run for a few minutes, turn off both the ignitions. It’s extremely important to turn off the engines before you remove the jump leads. If you remove the leads while the engines are running, it can damage the electrical systems of the cars.

Then, it’s time to disconnect the jump leads in the opposite order you connected them. This means:

• Take the black lead off the earthing point
• Take the black lead off the working battery’s negative (-) terminal
• Take the red lead off the working battery’s positive (+) terminal
• Take the red lead off the flat battery’s positive (+) terminal.

Again, it’s really important that the leads don’t touch each other or the cars as you remove them.

Once the leads are safely removed, return the car with the flat battery on again. If it starts, the car is safe to drive. It’s best to drive without stopping and starting for around 30 minutes after a jump start to charge the battery fully.

Mistakes to avoid when jump starting a car

Jump starting a car is quite a common thing to have to do, but you can seriously damage your car – and yourself – if you make a mistake.

Do not attempt to jump start a car if:

• The working vehicle you have access to is a hybrid or electric car
• Either of the batteries is damaged or leaking
• Your jump leads are damaged or if they become hot during the jump start. If the leads heat up, turn off the engine immediately and then remove the leads.

You should make sure to avoid smoking or using an open flame during the jump-start process.

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Portable battery chargers

A portable battery charger or jump starter can also help if your battery runs flat and you don’t have access to another car – for example, if your battery runs flat at night or you break down in the middle of nowhere.

To use a portable battery charger, begin by checking that none of your equipment is broken, worn, or leaking. Then, put the battery pack somewhere it won’t fall. It’s best not to put it on the engine itself, as the vibrations will likely knock it down once you get the engine to start.

Then, connect the leads:

• Connect the red lead to the positive terminal of the car’s battery.
• Connect the black lead to an earthing point on your car.
• Switch on the battery pack.
• Try to start the car, and let the engine run for five minutes if it does.
• Turn off the engine and disconnect the battery pack by removing the leads in the reverse order. 

How jump start a car properly: Conclusion

With the right equipment and access to a working car, it’s possible to jump start a car on your own if you follow the steps above. However, if you’re in any doubt, it’s best to call in the professionals.

Some car insurance policies include breakdown assistance, so you can get help from a trained mechanic if you need to jump start your car. To find out more about your policy options, contact the team at Howden today.

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