How to jump start a car

Flat battery? This is how to jump start a car, with or without jump leads

Jump starting a car because of a flat battery is something most people have to go through at some point. It becomes more prevalent in cold weather as the brisk temperatures slow down the reactions inside the car battery cells and reduce the voltage.

What’s worse is that because of all the electronics fitted to new cars, a standard 12-volt battery can be drained of its power rapidly. Slowly over time, your battery will lose its ability to hold a good state of charge. Meaning one morning (when you are probably running late) your car will refuse to start. When this does happen, being able to jump start your car is critical.

• Best intensive winter driving courses

Aside from anything else, learning how to jump start a car is an incredibly useful life skill which may be useful to more people than just yourself. Should your battery go flat, the processes described below to get your car going again show how easy it is to do yourself, and should, therefore, mean a call to the emergency breakdown services is not needed.

However, there are some common mistakes people make, so by reading the guide below you’ll get the full low-down on how to jump start a car correctly and safely. There are two common methods for jump starting a car. One of these requires jump leads and another (running) car, while for the other, you need to be able to get the car rolling to bump start the engine into igniting.

Whichever way you do it, you should get your car battery checked as soon as possible after jump starting. Replacing the car battery could very easily remedy the problem, but if there is trouble with the car’s alternator that means it’s not recharging the battery when you’re on the move, then this could result in a costly replacement.

How to jump-start a car with jump leads

  • 1. Position the two cars: 
    Move another car with a similar size engine (Car 2) close to your car (Car 1) so that the engine bays are close together. Move all metal objects out of the way of both batteries and remove loose clothing. Check that both batteries and your jump cables aren’t damaged.
  • 2. Connect the red jump lead: 
    Connect the red jump lead’s crocodile clip to the positive (+) terminal on Car 2’s battery, then the other end to the positive (+) terminal on Car 1’s battery
  • 3. Connect the black jump lead: Connect the black jump lead’s crocodile clip to the negative (-) terminal of Car 2’s battery, then the other end to an earthing point on Car 1.
  • 4. Start the engine: Start Car 2’s engine. Wait about 5 minutes and then start Car 1. Remove the clips in reverse order to the above.
  • 5. Run or drive the car: Run or, preferably, drive Car 1 for at least 15 minutes to let the battery recharge and allow it to start on its own.

See each step in more detail here.

Without cables (manual cars only)

  • 1. Get help Gather some friends to help push the car (not needed if you are parked facing downhill).
  • 2. Clutch and gear Push in the clutch (do not release until step 4) and put the car into second gear. Turn on the ignition.
  • 3. Push Have your friends start pushing the car, or let off the brakes if you’re on a hill.
  • 4. Release the clutch Once you’re moving, bring up the clutch quickly and the engine will start. Let the car run while it recharges.

See each step in more detail here.

Jump starting a car with jump leads: explained in detail

1. Safety always comes first when dealing with electricity. Make sure that there are no metal objects nearby, like tools or even jewellery, that could come into contact with the batteries or cables – and take off any clothing that could get caught inside the engine bay.

You should also make sure that the batteries of both cars aren’t damaged. If a battery’s plastic casing is broken or it looks like it is leaking, don’t try anything – either remove it yourself, if you know what you’re doing, or take it to a professional to be replaced. Likewise, if the cables are damaged it may be best to borrow someone else’s or buy some new ones – they’re not too expensive.

2. After you’ve moved two cars close together so that the leads will reach between the batteries, it’s time to connect the leads. Make sure both cars are completely off with the keys out and place a clip on the red jump cable onto the positive terminal – marked with a plus (+) symbol – on the battery of the car that works (we’ll call this Car 2).

Clip the other end of the red cable to the positive (+) terminal on the non-starting car (Car 1). Make sure both clips are on securely and will not snap off. You should also make sure the cables don’t fall into the engine bay and obstruct any moving parts.

3. Connect one end of the black jump lead to the negative terminal – marked with a minus (-) symbol – on Car 2’s battery.

The other end of the black cable should be attached to an earthing point on Car 1 – some cars have a dedicated point, but otherwise use any bit of solid metal attached to the engine block or chassis, like an unpainted bolt. This should be away from the battery and any fuel-related parts. A small spark as you connect it is nothing to worry about.

4. Now start Car 2 and let the engine run for a little while. After about 5 minutes you should be able to start Car 1. If it doesn’t start, then turn Car 2 off, gently adjust the clamps to ensure a good connection and then try again. If this doesn’t work you may need a new battery or other essential parts to be repaired.

Once Car 1 is running , the clips can be removed. Make sure you don’t touch any electrical components and only handle the insulated parts of the jump leads. Remove the leads in he opposite order to before: Earthed end of black lead, then the black clip on Car 2, then the red clip on Car 1, and finally the red clip on Car 2.

5. You will need to drive Car 1 or keep it running for at least 15 minutes to charge the battery up, but once it is running normally it can be driven as normal – just don’t turn it off before the 15 minutes are up or you risk having to repeat the whole process!

How to jump start a car without jump leads: detailed push start guide

1. Before you try push starting a car, you need to make sure it’s a manual car with a clutch. You can do this by reading the owner’s manual that came with the car, or simply by looking into the footwell.

You’ll also need a group of friends to help you get the car moving. If you can’t find any nearby, try asking some passers-by to help – they may even become your friends in the future, which would be a nice side-effect of having a flat battery. If you’re on a hill and you can get the car moving without any help, you’ll be able to start the car on your own.

2. Push in the clutch, and keep it depressed fully until step 4 (below). Put the car into second gear and turn the key so that the ignition light comes on.

3. Get your friends to start pushing the car, making sure that there is no traffic coming as you would when pulling off normally. If you’re on a hill, let the brakes off so that you start moving.

4. Once you’re on the move, at about 5mph, release the clutch quickly so that the engine and gearbox connect. The wheels will turn the gears, pulling the newly-connected engine along with them and starting the engine’s combustion cycle.

Come to a stop, leaving the engine running, and thank your companions for doing the legwork. Make sure you run the engine for at least 15 minutes to charge the battery before turning it off. You can use this time to make your friends a cup of tea, or simply drive away.

How to jump start a car with a portable power pack

Portable power packs are a way of starting a car without any extra effort. These devices carry enough charge to jump start your car simply by attaching the built-in crocodile clips to your battery’s positive terminal and to an earthing point – exactly like the steps for jump starting using another car (above). All you have to do then is turn the car on and remove the power pack, then leave the engine running to recharge the battery.

Check out our best mini jump starter packs here…

  • • Best winter tyres
  • • Winter driving tips
  • • Winter car checklist & best buys
  • • Hot new 4×4 cars coming soon
  • • Fact or fiction? 10 winter driving myths busted
  • • Best SUVs and 4x4s to buy now
  • • Best small 4x4s to buy now
  • • The world’s coldest roads

Leave a Reply

Your email address will not be published. Required fields are marked *