If you ever have a flat car battery, you might need to use jump leads (sometimes called booster cables) to start your car. Booster cables are a pair of thick wires with metal clips at each end that can transfer electricity from one battery to another. However, misusing jump leads can be dangerous and damage your car or cause a fire or explosion. Here are some tips on safely using car battery booster cables.

What You Need
- A pair of working heavy-duty jump leads (you can buy online here ).
- Another vehicle with a fully charged battery that has the same voltage as yours (usually 12 volts). Avoid using a hybrid or electric car, as this could cause damage.
- A safe and flat place to park both cars so that their batteries are within easy reach of each other (without the cars touching).
How to Connect the Jump Leads
- Turn off both engines and remove the keys from the ignitions. Also turn off any lights, radios, fans or other electrical devices in both cars.
- Open the bonnets of both cars and locate the batteries. They should have a red cover marked positive (+) and a metal post marked negative (-). Some cars may have special terminals for boost cable connections under the bonnet without accessing the battery directly.
- Connect one end of the red boost cable to the positive (+) terminal of the flat battery. Make sure the clip is firmly attached and does not touch any other metal parts.
- Connect the other end of the red boost cable to the positive (+) terminal of the good battery. Again, make sure the clip is secure and away from any other metal parts.
- Connect one end of the black boost cable to the negative (-) terminal of the good battery. Make sure the clip is firmly attached and does not touch any other metal parts.
- Connect the other end of the black boost cable to an earthing point on the car with the flat battery. This should be an unpainted metal part on the engine block or chassis that is well away from the battery and fuel system. Do not connect it to the negative (-) terminal of the flat battery as this could cause sparks or explosions.
- Check that all four clips are properly connected and that none of them are touching each other or any other metal parts.
How to Start the Car
- Start the engine of the car with the good battery and let it run for a few minutes. This will help charge up the flat battery.
- Try to start the engine of the car with the flat battery. If it starts, let it run for at least 15 minutes to allow the alternator to recharge the battery. If it does not start, wait for another few minutes and try again. Do not crank the engine for more than 10 seconds at a time as this could damage it.
- If you still cannot start the car with the flat battery after several attempts, there may be another problem with your car or your battery may be too old or damaged to take a charge. In this case, you will need to call a breakdown service or replace your battery.
How to Remove the Jump Leads
- Turn off both engines and remove the keys from the ignitions. NEVER remove jump leads with an engine running above idle speed.
- Remove the jump leads in the reverse order of how you connected them. Start with the black cable from the earthing point on the car with the flat battery. From the negative (-) terminal on the good battery, then remove the red lead from the positive (+) terminal on the flat battery and finally remove the remaining red positive (+) lead from the good battery.
- Be careful not to touch any metal parts with your hands or let any clips touch each other or any other metal parts as you remove them.
- Close both bonnets and store your boost cables safely in your boot.
How to Prevent Your Battery from Going Flat Again
- Check your battery regularly for signs of wear or damage, such as cracks, leaks or corrosion.
- Replace your battery if it is more than five years old or if it fails to hold a charge.
- Avoid leaving your lights, radio or other electrical devices on when your engine is off.
- Drive your car regularly and for long enough distances to keep your battery charged.
- If you do not use your car for a long time, disconnect your battery or use a trickle charger to maintain its charge.
There are some signs that can indicate your car battery needs replacing:
- Difficulty starting the car. If your vehicle takes longer than usual to start or makes a clicking sound when you turn the key, it could mean your battery is low on power or has a bad connection.
- Low or loss of power to electrics. If your lights, radio, windows, or other electrical devices are not working as well as expected or only work when the engine is running, it could mean your battery is not holding a charge well.
- Dashboard warning symbol. If you see a battery symbol illuminated on your dashboard, it could mean a problem with your battery, alternator or wiring. It would be best to get it checked by a professional as soon as possible.
- The condition of your battery. If you notice any physical damage, leaks, cracks, corrosion or swelling on your battery, it could mean it is old, worn out or defective. It would be best to replace it immediately to avoid further damage or safety hazards.
If you notice any of these signs, you should get your battery tested by a qualified technician or use a smart charger to check its condition and charge level.
I hope this blog post was helpful and informative for new drivers who want to learn how to safely use car battery boost cables.