A flat battery is the most common reason a car or van won’t start — a single click, dim lights, or a dead dashboard. Jump-starting from another vehicle or a jump pack gets you going in minutes, but the order you connect the leads matters for safety. Here’s the method that works on almost any 12 volt petrol or diesel.
First, Is It the Battery?
A flat battery usually gives a rapid clicking, very slow cranking, or nothing at all, often with dim or flickering dashboard lights. If the engine cranks briskly but won’t fire, the battery probably isn’t the problem — look elsewhere.
Before You Start
- Park the donor car close but not touching; both ignitions off, handbrakes on, in neutral or park.
- Use good jump leads or a lithium jump pack (make sure a pack is rated for a diesel if you’re starting one).
- Locate the battery — under the bonnet on most cars, though some have it in the boot or under a seat, sometimes with a dedicated remote jump terminal in the engine bay.
- Keep leads clear of the belt, fan and hot parts, and don’t let the clamps touch each other.
How to Jump-Start (Step by Step)
- Connect the red lead to the flat battery’s positive (+) terminal.
- Connect the other end of the red lead to the donor battery’s positive (+).
- Connect the black lead to the donor battery’s negative (−).
- Connect the other end of the black lead to bare, unpainted metal on the flat car’s engine — a bracket or lifting eye — not the flat battery’s negative terminal. Earthing to the engine keeps any spark away from the battery’s gases.
- Start the donor car and let it run for a few minutes.
- Start the flat car. If it doesn’t catch, wait a couple of minutes and try again rather than cranking continuously.
- With the engine running, remove the leads in reverse order: the engine earth first, then the donor negative, then both positives.
- Drive for 20–30 minutes (or leave it running) so the alternator recharges the battery.
With a jump pack, connect the positive clamp to the battery positive and the negative clamp to the engine earth point, then follow the pack’s own instructions.
After a Jump-Start
If the battery went completely flat you may need to reset the clock and radio, and re-initialise things like electric windows or the tyre-pressure system. If the car dies the moment you disconnect, or is flat again the next morning, the battery is likely worn out or there’s a charging or drain fault worth checking. Bump-starting (push-starting) only works on manuals and isn’t recommended on modern common-rail engines — a proper jump-start is safer.
Vehicle-Specific Jump-Start Guides
Battery location and a few after-steps vary by model — here are step-by-step guides:
- Vans: Renault Trafic, Fiat Talento, Nissan NV300, Vauxhall/Opel Vivaro, Mercedes Sprinter
- Cars: Hyundai i10, Kia Picanto, Toyota Aygo, Suzuki S-Cross, Mitsubishi Outlander, Honda Insight, Dodge Charger
If a warning light stayed on after the jump-start, look up the code on autodtcs.com.
