How to Jump Start Your Car
A 10-step guide to jump starting your car using jumper cables.
- Position cars close together so they’re bonnet to bonnet, without touching.
- Check that both cars are in neutral with the handbrakes on.
- Attach the red jump lead to the positive terminal of the flat battery, then to the positive of the charged battery.
- Attach the black jump lead to the negative terminal of the charged battery, then clip the other end to any metal bracket on the car with the flat battery.
- Ensure all leads are secure, then wait 3-5 minutes.
- Start the engine of the car with the charged battery. Let it run for a minute.
- Try to start the flat battery car. If it doesn’t work, wait a few more minutes.
- Once both cars are running, leave them on for 10 minutes. Stay nearby.
- With the engines on, first remove the black lead from the flat battery, then the other end of the black lead. Then remove the red lead from both cars.
- Keep the car running for around 20 minutes, then drive for 30+ minutes.
There are few ways to ruin a morning more quickly than getting into your car and finding out that the battery’s dead. It seems like such a small component, but makes a world of difference when it’s not working.
If you find that your car’s battery is regularly without charge, it may be that you need a replacement. You can either take your car for a free battery check, or purchase a new battery. Find out how to change your car battery, or use our locate a Centre tool to find your nearest repair centre.
Why do car batteries go flat?
With so much connected to them, batteries take a beating. But cars and car batteries are designed to meet the needs of all the devices connected to them – so a battery shouldn’t be going flat if everything is working as it should. If you’re finding your battery flat, here are some possible culprits.
Loose battery terminals
The first place to check is the most simple one (though one that’s most frequently overlooked) – loose terminals! Terminals should be clamped on fairly tight, so give them a wiggle, and clean (from the shielded part of the cable) to see if they move.
Discharge over time
Over time, batteries lose their power. So if you’ve not used your car for a long time then it might need to be charged or jump started to get it going again. That said, with modern batteries, this is usually only the case if the car’s not been turned on in a number of months.
Parasitic Drain
If a component such as a light, the radio, or anything else has been left on, then you’ll usually be able to tell once the car’s going again. A ‘parasitic drain’ is a component that draws small amounts of power from the battery when the car is off, but over time this can drain the battery.
These are things such as internal clocks on radios (so they know the date & time when you turn the car back on). Again, unless there’s been DIY work done on your vehicle, these should only be a problem over months of inactivity.
The battery’s too cold
Car batteries, like phone batteries, lose output ability in cold weather. Although the battery retains power, it can't deliver it efficiently at low temperatures. Modern batteries can function in cold conditions but are still affected over time. Jump-starting a cold battery is usually not recommended as it can cause damage. The best options are to wait for the weather to warm up or use a hairdryer to warm the battery if you need a quick solution.
Frequent short journeys
As much as the battery gets recharged when the car’s on, the power required to actually start the engine is so great that it’ll often take more than 20 minutes of the car running to recharge back to full. If you frequently drive short journeys then the battery doesn’t have a chance to fully recharge.
Old or faulty battery
Over time, batteries become less able to be charged and hold onto that charge. After around five years of frequent use, a car battery usually needs replacing. If your car jump-starts and then runs fine until you turn it off – then your battery likely needs replacing.
Faulty Alternator
If your car jump starts but then dies again within a few minutes, then your problem is likely with the charging side of things. An alternator on its way out will get gradually less able to charge the battery. They tend to last between 6-10 years – or up to 150,000 miles – before they need replacing.
How to check your car has jump-started correctly
If the engine on the flat-battery car appears to be running fine, then switch off the engine of the boosting vehicle. Now, it is worth checking that your newly jump-started car is capable of running ok on its own. So, switch on the air con or heater, the lights, the heated rear window, and any other electrical parts. This will prevent any voltage surges from happening.
It will take a little while for the alternator to fully charge up the battery now it has been jump-started, so it is advised that you keep the engine running for some time afterwards by going for a drive and trying not to stall.
If your battery consistently fails to hold charge, you may have a more serious problem. In which case, it is worth booking in for a free battery health check with the experts at Kwik Fit.
How to start your car without jump-start leads
There are two ways in which you can start your car if you don’t have access to jump leads: push-starting and using a ‘jump-start box’.
How to push-start your car
Push-starting, also known as ‘bump-’ or ‘pop-starting’, is a way of starting your car by — you’ve guessed it — pushing it. Instead of using a battery-powered starter motor or gaining power from a booster vehicle, the engine is bumped to life by force. All you’ll need to do this is a short distance on a flat surface and a good friend or two.
- First of all, have whoever is helping you stand at the rear of the car and get ready to push when required.
- Then get into the driver’s seat and start the ignition. Leave the handbrake on and push the clutch in.
- Next quickly shift to second gear, press the brake, and release the handbrake. Now bring your foot off the brake and have your trusty helpers start to push.
- When you reach 5mph, release the clutch sharply. Don’t worry, the engine may splutter and the car might ‘jump’ but this is a good sign as it shows the engine is engaging.
- If you’re lucky the engine will start. If not, repeat the steps above at a slightly higher speed.
How to use a jump-start box
Another effective way of jump-starting your car without jump leads is by using a jump-start box.
These boxes are essentially mini portable batteries with their own jump leads attached. Jump-start boxes are much safer than jump leads themselves as they have built-in software that prevents harmful voltage spikes from occurring. So how do they work?
- Make sure your jump-start box is fully-charged itself. If it isn’t, you’ll have to wait a while for it to charge.
- Check whether your jump-start box comes with integrated cables. Most should do nowadays, but if not, connect the cables to the correct posts — positive and negative.
- Similarly to actual jump leads, connect the red lead clamp to the positive post of your dead battery. This will be indicated by either a ‘+’ symbol or a red cover.
- Then, connect the black lead clamp to a grounded, unpainted metal surface on the frame of your car.
- Now everything is connected properly, switch on the jump-starter box. After a couple of minutes, start your vehicle.
- The car should start straight away, but if it doesn't, then wait a few more minutes to give the battery time to charge.
- Once the car has started, you’re good to go! All you have to do is turn off the jump-start box and remove the leads in reverse order and you’ll be on the road in no time.
What to do if your battery keeps dying?
Did you know? The Kwik Fit battery test is free, takes less than 10 minutes and could alert you to any battery faults that you may not have noticed yet. If you find that your car’s battery is regularly failing, it may be that you need a replacement. Visit your local Kwik Fit centre today, find out more about your vehicle and its health in our blog section, or contact our friendly team for further advice today.
1. Position cars close together so they’re bonnet to bonnet, without touching.
2. Check that both cars are in neutral with the handbrakes on.
3. Attach the red jump lead to the positive terminal of the flat battery, then to the positive of the charged battery.
4. Attach the black jump lead to the negative terminal of the charged battery, then clip the other end to any metal bracket on the car with the flat battery.
5. Ensure all leads are secure, then wait 3-5 minutes.
6. Start the engine of the car with the charged battery. Let it run for a minute.
7. Try to start the flat battery car. If it doesn’t work, wait a few more minutes.
8. Once both cars are running, leave them on for 10 minutes. Stay nearby.
9. With the engines on, first remove the black lead from the flat battery, then the other end of the black lead. Then remove the red lead from both cars.
10. Keep the car running for around 20 minutes, then drive for 30+ minutes.
