To jump start a car, first of all you need a set of jump-leads (sometimes referred to as booster cables). These will give you the opportunity to pipe battery power from another car (the donor) to get yours (the casualty) started. Always buy the best jump-leads you can afford; if they’re as skinny as a pencil, they won’t carry a lot of current without getting hot, but if they’re as thick as your thumb they’ll do the job nicely.
The battery terminals on both cars will be marked with a “plus” sign (positive) and a “minus” sign (negative) and the jump-leads are coloured red (positive) and black (negative). It’s important they’re connected correctly. You’ll need to have an idea of the battery location on both cars – that seems obvious, but it’s easy to spend a bit of time positioning the donor nose-on to the casualty only to find the battery is stored under the passenger seat.
Both cars should be positioned so the batteries are as close to each other as possible – not always easy as you can move only one car. Don’t let the cars touch each other though.
Once positioned, switch off the donor, make sure you have both sets of keys in your pocket and follow the steps below:
Connect the red jump-lead to the positive terminal of the donor…
…and then to the positive terminal of the casualty.
Connect the black jump-lead to the negative terminal of the donor…
…and then to the negative terminal of the casualty
Wait a couple of minutes for the two batteries to stabilise.
Start the ignition of the donor car first…
…and then start the casualty
Wait five minutes and turn off both cars
Remove the leads in the reverse order.
Restart the casualty and take it for a drive.
It’s important to follow this procedure to the letter as any sparking when connecting or disconnecting cables could damage the car’s electronics.
If the problem was caused by leaving a light or the radio on, that should be an end to the matter. Otherwise, it’s necessary to get the battery checked to be sure that it’s not going to let you down again.