How to Jump-Start a Car in Ten Simple Steps
FixMyCar provides a step-by-step guide to jump-starting a car.
Book a car repair nowEllie Dyer-Brown
Tuesday December 05 2023
8 min read
A flat car battery is the last thing you need at the start of a busy day, especially if you have somewhere important to be. Knowing how to jump-start your car makes all the difference in this situation.
In this guide, we provide step-by-step advice for jump-starting a vehicle in two different ways: using jump leads and a booster pack.
Jump starting a car with leads
Follow the advice below to jump-start a car with cables, commonly called jump leads.
What do I need?
You’ll need the following equipment to get your battery working again.
A pair of jump leads - a positive red lead and a negative black lead.
Your car with a flat battery, parked in an easily accessible place, and another car with a charged battery. Do not try to use a hybrid or electric car.
Safety advice for using jump leads
Without the proper knowledge, jump-starting a car can be dangerous.
Check your equipment
Do not try to jump-start your car if the battery is damaged or leaking.
Inspect your jump leads for signs of damage or wear; if you spot any, you shouldn’t use them.
Stop using your jump leads if you feel them getting hot.
Create a safe environment
Remove all jewellery and any dangling clothing that could get caught in the engine.
Make sure no metal objects come into contact with either of the batteries; this could cause a spark and potentially make them explode.
Do not smoke or allow any sparks near the vehicles.
Be mindful of when you remove the jump leads
Do not remove the leads when the engines are running; doing so could damage the cars’ electronic systems.
A ten step guide to jump starting your car
Follow these steps to get back on the road in no time.
Step One: Switch off electrical systems and devices.
Electrical components in the car with a dead battery - such as the radio, lights, and satellite navigation - should be turned off. It may help to lower the driver’s side window.
Step Two: Park the second vehicle close to the car with the dead battery.
The closer you can get the cars, the easier it will be to do a jump start. However, the vehicles should not be touching.
Step Three: Switch off both cars.
Ensure the keys are removed from the ignition and open the bonnets (or the boot if that’s where the battery is kept).
Step Four: Attach one end of the red lead to the positive battery terminal.
Often, the positive terminal has a red plastic cover with a plus sign (+) on it. Remove the cover to access the terminal.
Step Five: Attach the other end of the lead to the positive terminal on the working car battery.
Follow the same process discussed in step four.
Step Six: Attach one end of the black lead to the negative terminal.
You should clip the black lead to the working battery.
Step Seven: Attach the other end of the black cable to a good earth point on the car with the flat battery.
Ideally, a solid bit of metal in the engine would make a good earth point. Make sure it is away from the battery and fuel system.
Step Eight: Start the car with the working battery, then switch on the vehicle with the flat battery.
Let the working car run for a minute before you try switching on the vehicle with a flat battery. Leave them idling for ten minutes, still connected.
Step Nine: Switch the cars off and disconnect the leads.
Once both cars are switched off, remove the jump leads in reverse order (start by removing the black lead from your vehicle and end by removing the red lead from the other car with a working battery). Do not let the leads touch each other or any part of the cars as you remove them.
Step Ten: Restart the car that had a flat battery.
The battery should now be working and should start after a few tries. If it doesn’t, there may be a more serious issue that requires investigation by a mechanic. Once the battery is working, drive around for 30 minutes (avoiding heavy traffic) to put some charge back into it.
How to remove jump leads safely
As discussed earlier, you remove the jump leads in reverse order.
Make sure both engines are switched off.
Disconnect the black lead from the vehicle that had a flat battery.
Disconnect the other end of the black lead from the car with the working battery.
Disconnect the red jump lead from the same vehicle.
Disconnect the other end of the red jump lead from the car you have jump-started.
What to do if your car won’t start
If your car doesn’t start after you’ve used jump leads to get it going, there’s probably an issue with the battery, which may require a replacement. The best action is to contact a mechanic who can advise you about the problem.
Using a battery booster pack
It’s a great idea to keep a battery booster pack in your car. It provides the power needed to start your engine without having to involve another vehicle in the jump-starting process, making it much safer. Booster packs are also a good investment because they are rechargeable.
Safety advice before you start
Make sure the battery is in good working order, without any damage or leaks.
Take off any jewellery and remove loose/dangling clothes.
Eight steps to jump start a car with a booster pack
Step One: Check the booster pack.
The booster should be fully charged and placed somewhere stable. Avoid putting it on your engine, as it could easily fall off.
Step Two: Connect the red jump lead.
The red jump lead, which is positive (+), should be connected to the positive terminal of your car’s battery.
Step Three: Connect the black jump lead.
The negative (-) black jump lead should be connected to an earthing point on your car - ideally unpainted metal on the engine or chassis.
Step Four: Switch the booster pack on.
Once the leads are connected correctly, you can switch on the pack.
Step Five: Try starting the car.
When you turn the key in the ignition, it should start after a few tries. If it doesn’t, there may be something wrong with the battery.
Step Six: Leave the engine running.
Keep the engine running for around five minutes, after which time you can switch off the pack and let the engine run for another five minutes.
Step Seven: Switch off the vehicle and disconnect the booster pack.
Remove the jump leads in the reverse order of how you put them on.
Step Eight: Restart your car.
The engine should start without help from the booster pack. When it does, drive around for half an hour to put more charge into it.
If you're having trouble getting your car started and suspect there may be a problem with the battery, FixMyCar can help you find an affordable local garage for a repair or replacement.
Frequently asked questions
Can I drive my car after a jump start?
You can - and should - drive your car after a jump start. Doing so allows the alternator to give the battery more charge. Aim for at least thirty minutes, avoiding heavy traffic.
What do I do when my car battery dies?
Don’t panic - this guide explains what to do when your car battery is dead.
Does jump-starting a car drain your battery?
Using your car to jump-start someone else’s is fine as long as the battery is in good condition and you follow the correct steps. Make sure your battery isn’t old or damaged first.
How do you tell if your battery or alternator is faulty?
The battery and alternator present similar symptoms when faulty, making it hard to tell which is to blame. When your battery is defective, you will likely see the warning light on your dashboard. Conversely, when your alternator isn’t working, you will get a flat battery even after you jump-start your car. Here are five additional signs that your alternator isn’t working correctly.
Can you jump-start a hybrid?
Yes, you can - find out how to jump-start a hybrid battery in this guide.
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