Guide to Jump Starting Your Car

Updated 30 September 2025

A car battery can fail unexpectedly, leaving you stranded with a vehicle that won’t start. Fortunately, jump starting a car is a straightforward process that can revive a dead battery quickly and safely if done correctly. This guide covers all the essential steps to jump start your car safely using jump leads or a jump starter pack.

Safety First

Before attempting to jump start your car, take a few important safety precautions:

• Ensure the battery is not leaking or visibly damaged. If so, do not attempt a jump start and call a professional.

• Remove all jewellery and loose clothing before working near the battery.

• Keep away from any open flames or sparks around the battery.

• Turn off both cars completely, remove keys from the ignition, and engage handbrakes on both vehicles.

• Wear gloves and goggles if possible for additional protection.

Equipment Needed

To jump start your car, you will need:

• Jumper cables or a jump starter pack compatible with your car’s battery voltage (usually 12V).

• A second vehicle with a functional battery (if using jumper cables) or a charged jump starter pack.

Step-by-Step Jump Starting Using Jumper Cables

1. Position the Vehicles: Park the functional car close to the car with the dead battery ensuring the jumper cables can reach both batteries safely, but without the vehicles touching.

2. Open the Bonnets: Open the bonnets and locate the batteries in both cars. If the battery is in the boot, look for jump start terminals under the bonnet or consult the owner’s manual.

3. Identify Terminals: Locate the positive (+) and negative (−) terminals on both batteries. The positive terminal is often marked with a red cover or a plus sign, while the negative is marked with black or a minus sign.

4. Connect Red Clips: Attach one end of the red jumper cable to the positive terminal of the dead battery and the other end to the positive terminal of the good battery.

5. Connect Black Clips: Attach one end of the black jumper cable to the negative terminal of the good battery. For the dead battery, do not attach the cable to the negative terminal; instead, clamp it to a solid, unpainted metal part of the engine or chassis as an earthing point away from the battery and fuel system.

6. Start the Donor Car: Start the engine of the car with the good battery and let it run for about one minute to charge the dead battery.

7. Start the Dead Car: Attempt to start the car with the dead battery. If it doesn’t start, wait a couple of minutes and try again. Avoid running the starter for more than 5 seconds continuously.

8. Run the Engine: Once started, let both vehicles idle for a few minutes to ensure the dead battery gains enough charge.

9. Disconnect Cables: Turn off the car with the dead battery, then carefully remove the jumper cables in reverse order: negative cable from the previously dead car, negative cable from donor car, red cable from donor car, and finally red cable from previously dead car.

10. Recharge Battery: Keep the engine running or take your car for a 20-30 minute drive to recharge the battery fully.

Using a Jump Starter Pack

If using a portable jump starter pack, follow these simplified steps:

• Ensure the jump starter is fully charged before use.

• Connect the red clamp to the positive terminal and the black clamp to the negative or earthing point as above.

• Turn on the jump starter pack according to the manufacturer’s instructions.

• Start your vehicle engine once connected.

• After starting, turn off the jump starter and disconnect clamps.

Additional Tips

• Always consult your vehicle’s manual for any model-specific jump starting advice.

• If the battery continues to fail, get it tested or replaced by a professional.

• Never let the jumper cables’ clamps touch each other when connected to a battery.

• Avoid jump starting if the battery is frozen or severely damaged.

By following these steps carefully, jump starting a car can be a safe and effective way to get back on the road quickly after a dead battery incident.