How to jump start a car

The most common type of breakdown is a flat battery – and whenever it happens, it’s always inconvenient. A dead battery in your car can mean the difference between getting home safely and being stuck somewhere for hours. Flat batteries often happen in cold weather when they’re under pressure to perform. If you don’t use your car often it’s usual for car batteries to lose charge over time. If it keeps losing charge in normal conditions, there may be more of an issue. To get yourself back on the road, you can jump start your car. 

How to jump start a car with jump leads

The most common and effective means of jump starting a car is by using jump leads. All you need is; a second vehicle with a fully charged battery (avoid using a hybrid or electric car as this could cause damage), and a pair of quality jump leads.

Safety precautions before jump starting a car with jump leads

When jump starting a vehicle, it’s important not to take risks. Consult your owners manual first and if you’re not confident that you know what you’re doing seek help.

• Check for damage – if there’s any obvious damage to either of the batteries, or the jump leads, don’t risk attempting a jump start.
• Remove any rings or metal jewellery you’re wearing and make sure nothing metal touches the terminals on the battery.

Steps to jump start a car

Here are the steps to jump starting a car with jump leads.

1. Before starting, make sure any electrical systems or devices in the vehicle with the dead battery are switched off (lights, radio/CD, sat-nav, etc.) and if possible, lower the drivers window.
2. Park the second vehicle as close to the casualty vehicle as possible, without the vehicles touching, ensuring the jump leads will comfortably reach from one battery to the other.
3. Ensure both vehicles engines are switched off, remove the ignition keys and open their bonnets (or boot if the battery’s located there).
4. Attach one end of the red jump lead to the positive terminal on the flat battery. The positive terminal will usually have a red plastic cover with a plus (+) symbol on it. Pull the cover back to access the terminal.
5. Then attach the other end of the red jump lead to the positive terminal of the good battery on the second vehicle.
6. Attach one end of the black jump lead to the negative terminal of the good battery.
7. Then attach the other end of the black jump lead to a good earth point on the casualty vehicle – a solid metal part of the engine is usually best.
8. Now attempt to start the casualty vehicle. If it doesn’t start after a few attempts, it might be more serious than a flat battery.
9. If it does start, leave it running for about five minutes.
10. Switch off the casualty vehicle, disconnect the negative jump lead then check the engine starts again okay. Disconnect the remaining jump leads.

How to safely remove the jump leads

To safely remove the jump leads, do the following.

1. Switch off the engines on both vehicles.
2. Disconnect the black jump lead that is connected to the casualty vehicle.
3. Disconnect the other end of the black jump lead from the second vehicle.
4. Disconnect the red jump lead that is connected to the second vehicle.
5. Disconnect the other end of the red jump lead from the battery on the casualty vehicle.

After the leads have been removed

Restart the engine on the casualty vehicle. The battery will need to recharge fully for it to be fully serviceable, which is best achieved using a quality battery charger for several hours. In the meantime, if possible, drive the vehicle normally (not in heavy traffic) for around 30 mins to try to put some charge back into the battery.

How to jump start a car with a portable battery pack

If you’re worried about getting stranded with a flat battery when you are unable to call for help or seek assistance from someone, then you can buy a portable battery pack as a precaution, to keep you mobile if your battery goes flat.

Before you start

When jump starting a vehicle, it’s important not to take risks. Consult your owners manual first and if you’re not confident that you know what you’re doing seek help.

1. Check for damage – if there’s any obvious damage to either of the batteries, or the jump leads, don’t risk attempting a jump start.
2. Remove any rings or metal jewellery you’re wearing and make sure nothing metal touches the terminals on the battery.

Jump starting with a portable battery pack

Here are the steps to jump starting a car with a portable battery pack.

1. First check that the battery pack is fully charged.
2. Locate the vehicle battery – usually situated in the engine bay under the bonnet, but in some vehicles, it is located in the boot. It’ll probably be hidden under a plastic cover – unclip this and you should see the battery with its two terminals.
3. Connect the positive (red) lead from the battery pack to the positive (+) terminal of the battery. Connect the negative (black) lead to a good earth point on the casualty vehicle – a solid metal part of the engine is usually best.
4. Stand the battery pack on the ground next to the vehicle, the leads are usually long enough to reach the battery. Avoid placing it on the engine as it might fall off when the engine starts.
5. Once the battery pack is connected, switch on the pack and attempt to start the vehicle as you normally would. If it doesn’t start after a few attempts, it might be more serious than a flat battery.
6. If the vehicle does start, keep the engine running for about 5 minutes. Switch off the engine, then switch off the battery pack and remove the leads from the battery pack. Now restart the engine again.
7. The vehicles’ battery will need to recharge fully for it to be fully serviceable, which is best achieved using a quality battery charger for several hours. In the meantime, if possible, drive the vehicle normally (not heavy traffic) for around 30 mins to try to put some charge back into the battery.