How to jump start a car 2024

Andrew Brady

Written by

Andrew Brady

Jump starting a car

How to jump-start a car?

There are two ways to jump-start a car.

The first is the old fashioned way. Thirty years ago it was common to see two cars with their bonnets open, with a pair of cables connecting their batteries – this was jump-starting. Essentially, you're sending the power from a healthy car with a charged battery to the other car with a flat battery – the slug of electricity is enough to crank the sick car's engine and, with a few turns, it spins into life. Once the engine's sparked – and assuming there's nothing else wrong (like a faulty alternator) – from there the car can charge its own battery.

The downside of this system is you need another healthy car and someone with the time and will to help you out – not things you can always guarantee to find. 

Your second option is to use the car salesperson's friend – the jump pack. Jump packs are portable batteries that you can charge at home and then hook up to your car battery to get its engine spinning. Jump packs used to be relatively unwieldy devices, but lithium-ion technology means they are now highly portable. 

How to jump-start a car with leads?

'How to jump-start a car with leads?' can be explained in ten easy steps:

  • First off, ensure both cars are off with handbrakes on, and parked closely together.
  • Connect the positive, or live (red) jump lead to the working battery's positive (+, or red) terminal.
  • Connect the other end of the positive lead to the positive terminal on the dead battery.
  • Connect the negative (black) lead to the negative (-) terminal on the working battery
  • The latest advice is to NOT connect the negative lead to the negative battery terminal of the old battery as this creates a fire risk. It is safer to connect it to an earthing point under the engine bay. This could be on the engine block itself, a piece of unpainted metal or an officially marked earthing point. 
  • Start the healthy car's battery and let it run for a minute
  • Build its engine revs to 2500rpm to produce a strong current
  • The sick car should now start when you turn the key
  • No luck? Leave it for a few minutes and try again
  • When the sick car has started, remove the leads by reversing the process

Jump starting with a lithium-ion jump pack:

  • Make sure the car is turned off
  • Connect the supplied leads to the battery terminals, being sure to connect the negative (-) first
  • Turn on the battery pack
  • Start the car
  • If it doesn’t start, many jump packs are fitted with a ‘boost’ button, which delivers a stronger jolt of current. Press this, then try to start the car again
  • Once running, remove the leads – positive first (+) then negative (-)

How long does it take to jump start a car

Which method should I use?

Realistically, the days of needing to use a pair of jump leads and another car are well behind us. With the advent of lithium-ion jump packs, there’s no need to mess with two cars, two batteries and two leads. Using a small jump pack removes all the dangers such as accidentally clashing leads and so on. Just buy a jump pack, keep it charged up and if you ever end up with a flat battery, you can be on the road in a matter of minutes, rather than having to wait for the aid of another car and driver.

Related guides

How do I jump start an electric car?

Electric car jump start

You will need to jump start an electric car if its batteries are entirely drained. Yo may find that the lithium-ion batteries may not be able to be recharged unless the vehicle is jump-started via the 12-volt system, which gets the electronics to kick-in.  You may not be aware, but electric and hybrids do in fact have two batteries. 

One is the main battery that powers the car itself, but there's also a smaller 12v battery that powers the car's electrical components, just as you'd find in a conventional petrol or diesel car.

It's no different jump-starting either an electric car or a plug-in hybrid as it is to a conventional diesel or petrol car. But it can be a bit trickier - that's because the location of the battery is generally easy to find in a petrol or diesel car ... but with an electric or plug-in hybrid, it may require some searching. 

That 12-volt battery will power things like lights, the entertainment system and wipers, but also needs to be powered-up in order to get an the lithium-ion battery to charge, too. 

There's a few rules to remember if you're jump-starting an EV. If you're doing it with jump leads, you're going to need a petrol or diesel car to provide the boost (or, alternatively, use a booster pack) and an electric car shouldn't be plugged in to charge when you jump-start it. The reason for that is that it may cause damage to the car's electronics which can be incredibly expensive to repair.

Best jump starter boosters 2021

Hearing the dull ‘click’ of a flat battery — be it the result of age, having left the lights on or a sharp cold spell — doesn't have to ruin your day. Using a compact  jump starter booster pack is far less hassle than dealing with jump leads and also means you don’t have to rely on another car being around. Here are ten of the best jump starting booster packs around.

Ring High Power Micro Jump Starter

Ring jump starter booster pack

The Ring RPPL300 is a Lithium Cobalt LiCoO2 jump starter that's able to start 12v vehicles up to 3.0-litres. Along with the fact it's a jump starter, there are two USB ports, so you can use it as a power bank to charge phones and tablets, plus an LED torch. It fully charges in three hours and includes a micro USB charging cable along with a battery charge indicator on the side. The main unit is 16cm by 9cm so will easily fit in a glovebox, too.

At around £90 it may seem expensive but if you've ever had the misfortune of having a flat battery, you'll know it's a very sound investment. It will save you a lot of time and hassle waiting for a breakdown mechanic to arrive. The fact it has two USB ports makes it even more useful - handy if the kids in the back need to charge their tablets or phones on the move. For smaller engines up to 2.0-litres, Ring also offers the cheaper RPPL200.

RoyPow J08 Portable Car Jump Starter

Roypow jump starter booster pack

RoyPow J08 is a small jump starter, a power bank and a flashlight. You can jump start a dead battery in seconds, while the clamps offer protection against power surges, overcharging etc. The jump starter pack can jump-start petrol engined car up to 3.5-litres.

The 2.1A USB outputs allow for fast charging of phones, tablets etc and there are three flashlights modes for safety if your car breaks down in the dark. The J08 also comes with an 18-month warranty for peace of mind.


Tacklife jump starter booster pack

If you don’t want to spend a huge amount then this compact TACKLIFE unit could be ideal. It puts out a peak of 600A and it’s claimed capable of being able to handle up to 6.2-litre petrols or 5.0-litre diesels, so it should be able to get you back on the road.

Like the NOCO, it also features a host of additional functions – including an LED torch and the ability to charge mobile devices. A six-month warranty is standard.

DBPOWER 600A 18000mAh Portable Car Jump Starter

Dpower jump starter booster pack

This DBPower jump pack is able to jump start 12V vehicles (up to 6.5L petrol or 5.2L diesel engine) in seconds with 600A peak current and 18000mAh battery capacity. It can also charge phones, tablets, laptops etc at the fastest speed possible with the included adapters. It's small enough to store in the glove box and the LED Flashlight can switch between lighting, strobe and SOS modes.

The LCD screen shows the jump starter's working status, while the clamps can provide protection from short circuits, overheating, reverse-polarity, reverse-charge protection, overcharging etc. The DBPower jump pack currently has a 4.6 out of 5-star rating on Amazon from over 1000 reviews.

NOCO Genius Boost Pro GB150 2000A

NONO Genius jump starter booster pack

There are numerous compact lithium-based jump packs around these days but NOCO produces some of the most highly regarded units. The GB70 is one of its more expensive offerings but it’s packed with features. For starters, it's rated to put out a hefty peak power of 2000 amps  – which allows it to start petrol engines up to 8-litres or diesels up to 6-litres.

It also has integral 12V and USB connections for powering devices, an internal torch and a one-year warranty.

Sealey RS1312HV Roadstart Emergency Power Pack

Sealey jump starter booster pack

Sealey has a long history of supplying good tools and among its extensive line-up is a range of jump packs. This RS1312HV is an affordable offering that packs a stout peak output of 900A, so it can tackle bigger engines with ease, and it also features two 12V sockets and a USB port – so it can be used to power or charge other things.

It is bulkier and trickier to charge than lithium alternatives, though, but it is a durable and guaranteed for a year.

NOCO Genius Boost Pro GB150 4000A

Noco genius boost Pro jump starter booster pack

If you want a compact lithium jump pack that’s guaranteed to get pretty much anything going, and you have a big budget, then this NOCO offering could be just the ticket. It packs a peak output of 4000A and, according to NOCO, it can be used to start up to 10-litre petrol and diesel engines. NOCO claims it can do 80 jump starts on a single charge.

It has integral 12V and USB connections for powering devices (an iPhone 8 seven times and a GoPro Hero 16 times). It can also be used to power useful tools like tyre inflators. It offers an internal torch and a one-year warranty as well.

Clarke JumpStart

Clark jump starter booster pack

This comparatively inexpensive heavy-duty Clarke starter pack is ideal for those needing to get bigger engines started, as it can put out a peak of 1500A – helping it turn over obstinate engines without hassle; Clarke recommends it for petrol engines up to six litres and diesels up to four litres.

It also has an integral light, a 12V socket and an isolator switch. A 12-month warranty is standard. It is heavy, though, weighing a hefty 17kg due to its lead-acid battery.

Suaoki U29 jump starter & air compressor

Suaoki jump starter booster pack

If you’re looking to cover as many bases as possible then you may well want to get a combined jump pack and compressor. This Suaoki U29, for example, features a powerful lithium battery that can put out 2000A peak and an air compressor; consequently, you’ll be able to sort flats of both the battery and tyre kind.

It also has a multi-mode torch, which can strobe or turn red for emergencies, as well as 12V and USB ports. A one-year warranty is standard.

CTEK MXS 5.0 12v battery charger

CTEK jump starter booster pack

Okay, so this isn’t a jump starting pack – but bear with us. If you've got a car that’s often sitting for long periods, and the battery discharges to the point where you always need to jump-start the car to get it going, it’s worth investing in a trickle charger. It’ll keep the battery in good health and your car will always be ready to go.

We wouldn’t be without a battery charger and, for £65 (and a five-year warranty), we reckon this is a tough product to beat. It’s sturdy and it works well. We’ve bought several batteries back from the dead. It’s a quick worker as well. Plus, the opportunities for leaving it connected make it ideal for car owners who garage their pride and joy over the winter, or those who don’t clock up quite enough miles to recharge the battery over the course of a weekend.

It should take about five minutes to jump start your car following the steps outlined above. 

If you turn the key nothing happens, your battery is most likely dead. If there's some charge left in the battery, your car's engine may turn but not crank into life. Dim headlights are a clear giveaway your battery is weak.

When jumping a car, first attach the negative lead (black) to the negative terminal marked '–' to the flat battery. 

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