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jump lead
  1. Breakdown
9th May 2022

How to jump start a car with jump leads or a booster pack

This blog provides a step-by-step guide to safely jump starting a car with a flat battery using jump leads or a booster pack.

Car Insurance from just £125 per year

You never know when your car battery is going to let you down, so it’s a good idea to carry a set of jump leads in the boot. They take up very little space but can get you out of trouble if your battery does fail. This blog explains how to use jump leads effectively and safely.

Before you jump start a car: make sure you’re safe

Before you try to jump start a car, remember that batteries produce flammable gases and an electrical charge, so you should follow these steps to stay safe:

  • Ensure you are in a safe place so you can get under the bonnet without harming yourself or others
  • Ensure you have no dangling clothing, such as a tie or scarf, as they can catch in the engine’s moving parts
  • Don’t let anything metal – such as tools, rings, watch straps and stray wires – touch the car batteries as they could spark and cause an explosion
  • Don’t smoke or allow naked flames anywhere near the engine compartment
  • Don’t try to jump start a battery that is damaged or leaking
  • Never use damaged jump leads
  • Switch off both car engines and stop using the jump leads if they get hot or begin to smoke
  • Don’t let any metal objects touch the car batteries – these could cause a spark and possibly make the battery explode. That includes rings, necklaces, watch straps, hand tools, clips, stray wires, etc.
  • Don’t remove the jump leads while the engines are running as this can cause serious damage to the cars’ electronics
jump lead

Step-by-step guide to jump starting a car with jump leads

1. Find someone with a car who can help

You will need to find someone who has a fully charged battery and is willing to give your car a boost. Hybrids and electric cars are not suitable. 

2. Put the cars in position 

Manoeuvre the booster car so that both batteries are within easy reach of each other. Depending on the position of each car’s batteries, they may need to be very close, but they must not touch each other. 

Next, apply the handbrakes of both cars and switch off the ignitions. 

3. Clip the jump leads in place

Clip the red jump lead to the working battery’s positive (+) terminal and clip the other end to the flat battery’s positive (+) terminal.

Next, clip the black jump lead to the working battery’s negative (-) terminal and clip the other end to an earthing point on the engine block. 

4. Start the booster car

Start the booster car and let it idle for a couple of minutes.

5. Turn on the engine of the car with a flat battery

Start the car with the flat battery, letting both cars idle for a few minutes. It may take a couple of attempts for the car to jump start. 

6. Wait for about ten minutes

Leave both cars idle at a fast tick over for about 10 minutes.

7. Turn off both engines and disconnect the jump leads

Next, turn off both engines and disconnect the jump leads in the reverse order to the way they were connected, removing the black lead from your car first and finishing with the red lead from the booster car.

8. Restart your car

Finally, restart your car and drive it normally for around 30 minutes to enable the battery to fully recharge. 

Read our blog for more guidance on what to do if you have a flat car battery.

Jump starting a car with a battery booster pack

If you have a car battery booster pack, you won’t need anyone else’s help to boost your failed battery.

When you are using a booster pack, you will need to follow the same safety advice for getting a jump start from another vehicle. The procedure using a booster pack is very similar to using a booster car.

jump lead

Step-by-step guide to jump starting a car with a booster pack

1. Make sure the pack is fully charged

Before you start, make sure the pack is charged fully and position it somewhere stable and close to the failed battery. But don’t sit it on the engine as it might fall off when the engine starts and vibrates.

2. Clip the leads in place

Clip the red positive (+) jump lead from the battery pack to the positive (+) terminal of the car battery.

Next, clip the black negative (-) jump lead to an earthing point on your car. 

4. Turn the booster on

Check the battery pack’s connecting clips are secure, then switch the booster on. 

5. Restart your car

Restart your car, letting the engine idle at a fast tick over for about five minutes after you have jump started it.

6. Switch off the boosted pack

Turn off the pack and allow the engine to run for a further 5 to 10 minutes so the battery can recharge itself.

7. Turn off the engine and remove the leads

Switch off the engine and remove the jump leads in the reverse order, first disconnecting the black lead, then the red lead.

8. Restart your car

Turn the keys in the ignition and drive the car normally for around 30 minutes to enable the battery to fully recharge.

9. Get your battery checked at a garage

If you’re still worried about what might have caused the battery to drain, it’s a good idea to get your car checked at a garage.

10. Recharge your booster pack

Make sure your booster pack is recharged so it’s ready to go the next time you need it.

Read our blog to learn everything you need to know about car battery maintenance

Help if you can’t jump start your car

If you can’t jump start your car, you will probably have to get some professional help. Whether your problem is a flat battery or something more serious, you can rely on Sterling Rescue breakdown insurance. Cover costs from as little as £25.42 a year – that’s a lot of peace of mind for very little money!

And if you breakdown and don’t already have cover, just give us a call on 0344 381 9959 and you can get instant breakdown cover from as little as £173.60 a year. 

 

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