Jump starting is simple in principle, but modern cars with stop-start systems, hybrid drivetrains and sensitive electronics need more care than the old rules of thumb suggest. This guide explains the basic connection order, the mistakes that cause damage, and when it's safer to leave it to a professional with a protected booster pack.
Check your handbook first
Many modern cars have specific jump-point locations under the bonnet or in the fuse box, and some manufacturers advise against connecting directly to the battery. Look in the handbook before connecting anything.
The basic order of connection
Connect red to the positive terminal of the flat battery, then red to the positive of the good battery, then black to the negative of the good battery, and finally black to a bare metal earth point on the stalled car, away from the battery.
Start the donor, then the stalled car
With leads connected, run the donor vehicle for a couple of minutes, then try starting the stalled car. Once it is running, remove the leads in the reverse order.
Why modern cars need more care
Stop-start systems, hybrid drivetrains and sensitive electronics can be damaged by voltage spikes from badly connected jump leads. This is one reason professionals use a protected booster pack instead.
After the car starts
Keep it running and drive for at least thirty minutes if you can. If it fails to start again the next day, the battery or the charging system needs testing.
When not to try
Do not attempt a jump start if the battery is cracked, leaking or frozen, or if you are not sure which terminal is which. Call us instead.
Common questions
Which jump lead goes on first?
Red to the flat battery's positive, red to the donor's positive, black to the donor's negative, and the last black clamp to bare metal on the stalled car away from the battery.
Is it safe to jump start a hybrid?
Often yes at the designated jump point, but you should follow the manufacturer's guidance. Many hybrids cannot be used to jump other cars.
How long should I run the engine afterwards?
Around 30 minutes of driving gives the alternator a reasonable chance to recharge the battery, though a weak battery may still fail again.
Why use a booster pack instead of jump leads?
A protected pack avoids needing a second vehicle and reduces the risk of voltage spikes, which matters on modern electronics.