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How to jump start and bump start a car

Battery flat and need to jump start your car? Even if it’s winter and the weather’s miserable, we’ve got what you need to know – so you can charge right ahead.

Driver attempts to jump start their car

Jump starting your car – what you need to know

The most common type of breakdown is a flat battery – and it’s always inconvenient.

Flat batteries often happen in cold weather when they’re under pressure to perform. Or when your car’s not used much.

To get yourself back on the road, here’s our quick all-you-need-to-know guide.

What do I need?

  • A pair jump leads
  • A second car with a battery in good order

What do I do next?

You need to organise the rescue car and connect the jump leads. Don’t worry, it’s straightforward – just a few simple, safe steps.

1. Park the rescue car close by. Make sure both have their hand brake on and can’t move forward or back. Some handbrakes are electric.

2. Switch off all your car’s electrics. This includes radio, fan and anything else. Don’t forget devices – phones or tablets, for example – perhaps still connected to any USB outlets.

3. Connect the red lead. Place the positive (+) red lead on your battery’s red terminal. These look a bit like crocodile clips. Then place the other red ‘croc clip’ onto the rescue vehicle’s red battery terminal.

4. Connect the black lead. Join the black negative (-) clip to the healthy rescue car’s battery. After this, place the negative black lead on some bare metal of your car. That could be bumpers or the bonnet. Even part of the engine. Take care not to scratch any exposed paintwork!

5. Start the engine of the rescue car. Keep it running. If the problem is only a flat battery your own car has an excellent chance of starting.

6. Start your car. Keep both cars running for around 10 minutes at around 2,000-2,500rpm. Your rev counter tells you your engine speed.

7. Disconnect the leads. But make sure you switch your car off before removing the jump leads. If you don’t you could damage your car’s electrics.

And don’t forget to thank your neighbour or friend who helped you out with their car!

What to look out for before jump-starting your car

If your battery is leaking or looks damaged it’s not a good idea to charge it.

Also, don’t let the positive and negative cables touch – they can short out and damage your car’s battery.

Remember, modern cars are full of electronics. Jump-starting a car the wrong way can potentially damage your car’s ‘brain’ – the electronic control unit or ECU.

The ECU controls your car’s decision-making. It can be very expensive to replace! So…connect positive to positive and negative to negative – always!

A word on electric and hybrid vehicles here. It’s not a good idea to use an electric vehicle or hybrid as the donor rescue car. While electric cars often use an extra same-style battery, they can be damaged by jump-starting another vehicle. So, stick to traditional petrol or diesel power!

Oh, and do make sure you know exactly where your car key is. Trying to re-start your car is not the time to be locked out!

How do I remove jump leads safely – five basic steps

1. Always turn your engine off. If your battery’s just on the low side you should now have enough juice to re-start it.

2. Removing battery leads should always be done in the reverse order they were connected.

3. If you remove the jump leads when your engine’s running your car’s electrics could be damaged. Try to avoid.

4. So, remove the black lead from the earth (or bare metal) point from your own vehicle first. Then, remove the other black lead end from your donor vehicle.

5. After this, remove the red lead from the donor vehicle. The last lead to remove is the red lead end from your car’s battery.

How do I keep safe when jump-starting my car?

Trying to fix your car’s battery when you need to be on the road is stressful. Jump-starting your car safely though is straightforward.

To keep your stress level down it’s a really good idea to adopt a few common sense guidelines to avoid any risks.

1. First, make sure you and your family are out of the way of traffic and harm’s way – including your vehicle and the healthy ‘donor’ car. Also, make sure the hand brake on both vehicles is on.

2. Keep any metal objects like watches, rings, coins and hand tools well away from both car batteries and the cables. 

3. If it’s cold and you’re wearing a scarf, whip it off. The same goes for anything which can dangle or get in the way – tie, handbag or messenger bag. Car fan belts and anything ‘strappy’ is a bad mix!

4. If the hazards lights are on, switch them off unless they limit your on-road visibility. These lights gradually drain a battery.

5. Once your car’s running, remove the jump leads in the reverse order they were connected. But never remove the jump leads when the engine’s running.

When we’re anxious we’re more liable to take risks or take chances. So do always take it steady.

What’s the difference between jump starting and bump starting my car?

A bump start only works with cars with a manual gearbox. So if your car’s an auto the bump option’s out – sorry!

A bump start is also called push-starting or clutch popping. To keep it simple we’ll stick to bump start.

This means your car is pushed along a low speed (don’t forget to release the hand-brake!). The driver then releases (or drops) the clutch forcing the engine and gearbox to engage.

Sometimes the clutch is ‘dropped’ in second gear to its ‘bite’ point, not first. The advantage of second gear is that it doesn’t slow you down so much.

With a bit of luck, the combustion cycle’s complete and your car engine has burst back into song. Don’t forget to shout out some thanks to your supporting pushers. 


What do I need?

A friend – two or three perhaps!

Some passers-by or family members if there’s a temporary shortage of willing bodies.

A hill is pretty handy as it gets you rolling without a human ‘push’ option.

Before a bump start do switch off anything that’s draining the battery. So headlights, music and blower. Even your car’s interior light.

The point is that you give your car the best possible chance to burst back to life – with the help of engine, gearbox and people power!

A tow from another vehicle is an option too.

Can I jump start a car on my own?

Yes you can. You’ll need a booster pack which are easy to buy online. Make sure it’s fully charged, or has had a recent re-juice so your car’s got the best chance to fire back to life.

There’s a few basic steps to follow. A booster pack has two cables, red and black. So:

1. Attach the booster pack’s red cable to the red, or positive, battery terminal on your car.

2. Then attach the black, or negative, terminal clamp to something metal and solid in the engine bay. Possibly the chassis or part of the engine block.

3. When everything’s connected up, turn on the battery pack.

4. Try starting your car. It may need a couple of tries if there’s nothing wrong.

5. Once the engine’s fired back into life keep it running for 5-10 minutes to charge up a bit more. Keep the battery pack on.

6. Then, turn off your engine and the battery pack. As long as the problem is a weak charge, you should be fine to get going again.

7. Within 30-45 minutes of driving your battery should be back to operational power. So perhaps give your car a proper chance to get its battery mojo back a bit.

If you don’t use your car often it’s usual for car batteries to lose charge over time. If it keeps losing charge in normal conditions, there may be more of an issue.

Car battery boosters, on the other hand, can vary a bit in how they work. But they’re basically all the same – portable power on tap when you need it most.

Booster packs are brilliant in another way – you’re not dependent on bothering another person for help.

Don’t forget to keep one topped up, every so often. Some take 10 hours to fully charge. A re-charge every three months should do it.

If your household has several cars a booster pack is invaluable.

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How often do car batteries last?

A good quality battery can last many years. Even the lifetime of your car, if you’re very lucky. Most of us aren’t so lucky.

Like everything, all batteries die eventually. If yours is more than five years old and is struggling on colder mornings, get it checked out.

Poor charging is sometimes linked to an alternator fault. It’s not always a battery issue. But remember, car batteries work a lot harder than they used to.

Modern cars, for example, turn their engine off at traffic lights to keep emissions down and to save fuel. Yet wipers, lights and audio stay on. There’s also more electronic ‘active’ safety tech on board.

Oh, and cars are also heavier than they used to be to meet safety legislation.

So your multitasking battery really has its work cut out!

Is jump starting bad for your car?

It can be. It depends on your car and its age. All modern cars have an electronic engine control unit (ECU). Small but mighty the ECU is basically a computer – or your car’s brain.

It handles all the decisions about fuel mixture and even how your brakes and air con work. If your jump leads are short circuited and there’s a power surge this ECU can be quickly damaged. Some ECUs can be expensive to replace.

There’s also the risk of damage to any components a damaged ECU might cause. For example, a power spike might potentially compromise your car’s headlight units or exhaust system.

(We did mention all that multitasking).

So if you’ve got a flat battery, be careful about how you handle the jump leads.

If you’ve a car which is started by an older-style key (rather than a push-start button), don’t leave it in the ignition when the jump leads are connected. But it’s fine to pop the key back into the ignition after the leads are clamped on.

If in any doubt, do check your car’s instruction manual. If you can’t find it, many are available online.

Or, call the roadside assistance recovery company. If you don’t have breakdown cover, you might be surprised by how little 24/7 support costs.

Your car insurance provider may even offer breakdown cover, but be sure to check. And remember, always shop around!

Why do car batteries get flat?

Car batteries lose their charge over time. Bad weather’s often a big contributor here. The lower the temperature, the harder the battery has to work.

If you tend to use your car for short runs your battery doesn’t get a chance to recharge properly. Short journeys limit a battery’s ability to keep its charge. Long term, that drives down your battery’s working life.

Tip: If you’re worried about your car battery and you don’t use your car much as you used to, perhaps buy a trickle charger.

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  Low-voltage trickle chargers can keep up the health of your battery without overcharging them. ‘Smart’ ones work out your battery’s charge level, then adjust the power.

Which means you’re always ready to go, even when you haven’t driven your car in ages.

Trickle chargers are also great if you have a classic car that only gets a few outings a year.

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