Where do you ground a negative jump lead?

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.

These can be purchased from the RAC shop and are able to jump start a car without the use of another vehicle.

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, give the RAC a call on 0330 159 1111 and we’ll be happy to 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.

Jump starting with a portable battery pack

First check that the battery pack is fully charged.

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.

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.

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.

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. In this event, seek professional help by calling the RAC on 0330 159 1111.

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.

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.

If your MOT is due or if you would like to book your vehicle in for a full car service, you can book online with your local RAC Approved Garage today.

Hopefully you won't need this information anytime soon, but make sure you have breakdown cover, van breakdown cover or business breakdown cover sorted just in case!

If you have a flat battery, starting your car can be next to impossible. With a set of jumper cables and a good Samaritan on hand however, you can be back up and running in no time at all.

Late model cars are generally more dependent on complex electronics to function and any voltage spike can damage the delicate electronic circuitry. Quality jumper leads fitted with a 'spike guard' or 'surge protector' should always be used and are available online or from any Supercheap Auto store.

NOTE: If the vehicle will not start, the charge indicator shows a fault or the alternator light is on, you should stop what you are doing immediately and contact your local auto club or local mechanic. In these circumstances the issue may not be battery related.

If you're looking to jump start a car with a Jump Starter pack, check out the how to jump start with a jump starter article Click Here.

Will Jump Starting my Car Damage the Electronics?

Jump starting a car could potentially damage sensitive electronics, but only if it is not done correctly, or those electronics aren’t correctly wired up in the first place. Usually, and provided that you follow the correct procedure, there is absolutely no risk to either vehicle when jumpstarting a car. The most likely damage caused if the cables are reversed or connected wrong, is to your car’s fuses. High quality jumper cables, and modern cars themselves are usually built with surge protection, so you only really run the risk of blowing fuses. It is still important to be careful and to ensure that you don’t allow live cables to touch anything they shouldn’t.

Can a Car Battery Be Too Dead to Jump Start?

Unfortunately, sometimes a car battery can get so dead that it simply can’t be jump started anymore. Often a “dead” battery will still discharge power, it just won’t be able to reach the standard 12-volt range and so won’t be able to turn over your car. Check for excess buildup around the terminal posts, leaks, spillage, swelling or overall corrosion as these are often signs of a battery that is too far gone to jump start. If it is unable to be jump started or even recharged, then it is time to recycle your old battery at your nearest Supercheap Auto - absolutely free of charge (no pun intended.)

Why Don't You Connect the Negative When Jumping a Car?

When you hook up a set of cables to jump start a car you should never connect the black cable to the negative terminal on the old battery. You don’t actually need to, since the circuit will still be completed when you connect the cable to ground - but the reason it isn’t recommended is because batteries can omit volatile gases. These gases are often highly flammable and any sparks from a connected battery could cause an explosion or fire risk.

Connect the positive at the battery terminal first (there is no danger of a spark as a complete circuit is not formed) then connect the negative cable to a point on the chassis or engine, away from the battery, so the resulting spark is not in the area likely to be affected by any gases.

Does Giving a Jump Drain Your Battery?

Anything your battery does drains your battery, however as long as it doesn’t fall below operational voltages, your battery should be more than capable of jump starting another car. If your vehicle is running, the power you are sending through to the flat battery is actually being generated by your alternator so you’ll usually find that your battery’s voltage won’t really change at all.

How Long Should You Drive After Jumping a Car?

As mentioned, you should drive your car for at least 30 minutes after jump starting it, in order to give your alternator enough time to fully recharge your battery. The alternative to this is if you have a battery charger at home and can simply drive home to charge your battery there.

Where do you ground negative jumper cables?

Where do you put the ground wire on a jumping car?