How To Use Jump Leads On A Car The Right Way

No matter when you break down, it’s always at the worst possible time. Thankfully, a flat battery doesn’t mean the end of your journey, and you can use jump leads to put some life back into your car. This article is the ultimate guide on how to use jump leads on a car. 

While jump leads are a great way to stay on the road, not everyone knows how to use them, or which part goes where. For something so simple, there are dangers involved when trying to jump-start a car.

This guide will help you out when you need to know how to use jump leads on your vehicle.

What Do Jump Leads Do?

If you have ever been in a situation where your car won’t start because of a flat battery, you’ll know that jump leads can really save the day. They work by transferring electrical charge from a working car battery to one that is flat.

The leads will temporarily connect two cars. Allowing the one with a flat battery to ‘feed’ from the other and recharge enough to get the disabled car running again.

Jump leads typically have crocodile clips at either end to make it easier for them to attach to a car’s battery and transfer that much-needed energy.

How To Use Jump Leads On A Car Battery

It seems simple enough, but if you ever ask yourself, ‘How do you jumpstart a car with leads?’, you may not actually know the answer. 

We’re going to explain where to connect your jump leads and how to attach jump leads to a car safely.

The first thing you need to do before connecting anything is to check that your battery is actually the problem. 

One of the easiest ways to check if your battery is flat is to turn on your car’s headlights. If the lights are dim your battery is the problem. However, if they are bright it’s probably something else.

You can also check to see if your battery is working by putting the key in the ignition and checking for any signs of life on your dashboard.

Once you are satisfied that your battery is flat, it’s time to figure out your next steps.

You will need another car to help you out. So it’s best to ring someone to come and help or hope you can flag someone down nearby.

Make sure the working car parks with its bonnet as close to yours as possible but not so close they are touching.

Open up both bonnets and look for the negative and positive terminals on either battery. 

The positive terminal will have a plus sign on it while the negative terminal has a minus sign.

How To Connect Jump Leads To A Battery

Knowing how to use jump leads correctly is about connecting them in the right order and doing so in a safe manner. 

Incorrectly connecting the leads can be dangerous to the people nearby. While it may also cause some serious damage to one or both vehicles.

Firstly, connect the red cable to the positive end of the working car’s battery. And then attach the other end of the cable to the disabled car’s positive terminal. 

Then, connect the black cable to the working car’s negative terminal.

It’s important to note that your next step isn’t to connect the final clamp to the negative terminal on the flat battery.

Instead, find an earthing point on the disabled car’s engine. Which is typically an unpainted piece of metal on the chassis or engine block.

Leave both engines off for a few minutes, before turning on the working car and leaving to run for one minute. This minute of running helps to recharge the disabled car’s battery. After 60 seconds of this, turn on the other car and leave both engines to idle.

Give the working car’s accelerator a pump every so often to surge more energy into the flat battery. And continue to leave both running for 10 minutes. 

After 10 minutes, turn off both cars.

Once both engines have been turned off, begin to disconnect the cables in the reverse order you attached them.

This means you will be starting with the black cable attached to the earthing point and working backward toward the first red cable you attached to the working car.

With everything now detached from both vehicles, it’s time to turn on the car with the recharged engine.

If it doesn’t restart, there is likely a wider issue with your vehicle. And it’s one for a mechanic to take a look at.

Once you have successfully recharged your car’s battery, you should drive it normally for at least 30 mins to fully recharge it. 

Sitting in stop-start traffic won’t be enough to let the alternator do its job, so you’ll need to give your car a good run.

Jumping Using A Battery Booster Pack

You no longer have to worry about flagging someone down to jump your car. 

These days you can buy battery booster packs that allow you to jump your car on your own. 

When using a battery booster pack to jump your car, the cable order remains the same as though you were doing it with another vehicle.

The Potential Dangers


There are some real dangers when trying to jump-start a car, so check these warnings out. 

If the cars are touching when you jump-start the battery, a dangerous electrical arc can form between them. This may harm anyone nearby, or it could damage your car.

It’s important to inspect the quality of your battery before you jump start it. Specifically, you are looking for any cracks or leaks, although any other damage should also be noted.

 If you discover your battery is damaged, don’t try to start the car yourself. Instead, it’s safer to call roadside assistance who are trained for these situations.

There is a very real electric current passing through the jump leads. So it’s important to take as many precautions as possible. You must ensure that the cables are not touching each other. If they do, then that can also create a dangerous electrical arc.

If you cannot find a suitable earthing point when connecting the final black cable, you can attach it to the negative terminal on the battery.

However, there is a risk of releasing unwanted hydrogen gas from the battery so it’s best to avoid it if at all possible.

Hopefully, you never need to know this information. But it’s always best to check how to use jump leads on a car before trying it. 

Jump leads aren’t the only thing you should keep in your car for emergencies, however. Check out our Emergency Car Kit Checklist to find out more.

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