Insider's Guides > Battery + Spark Plugs

Car Maintenance

Also in Car Maintenance
Inside Battery + Spark Plugs
1. Battery Replacement
2. Jump Start
3. Spark Plugs
Battery + Spark Plugs
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Jump Start

If your car won't start because the battery is flat, jump-starting will get you out of trouble.

jump start
You will need:
  • A set of jump leads
  • Access to a booster battery
  • (Probably in a friend's car)

1 Position another car near yours so that the batteries are close, but do not let the vehicles touch. Switch off the ignition and all electrical equipment on both vehicles, apply the handbrakes, and ensure that the gears are in neutral (manual transmission vehicles) or 'P' for automatics. Open the bonnets.

2 Connect one end of the RED jump lead to the POSITIVE (+) terminal of the flat battery 'DO NOT let the other end of the red lead touch any vehicle metal' and connect the other end of the RED lead to the POSITIVE (+) terminal of the boosting battery.

3 Connect one end of the BLACK jump lead to the NEGATIVE (-) terminal of the boosting battery and connect the other end of the BLACK lead to a bolt or metal bracket, well away from the battery, on the engine block of the vehicle to be started.

jump start
4 Ensure that the jump leads cannot come into contact with any moving parts of either engine. Start the engine of the boosting vehicle and run it at a fast idle speed. Now start the engine of the stranded vehicle and check that it is running properly.

5 Stop the engine of the boosting vehicle only and disconnect the jump leads in the reverse order of connection.

6 Keep the use of all electrical equipment (radios, heaters, interior lights etc) to a minimum and remember that it will take some time for the alternator to charge the battery sufficiently. Don't stop the engine again too soon and try not to stall it whilst driving!

Haynes Hints

  • Jump leads come in various qualities; generally you need heavier-duty ones for diesel engines and larger petrol engines. Ask at your local Halfords for advice if you're not sure what sort to get. Beware of very cheap jump leads from market stalls and boot sales - they can overheat and even catch fire.
  • If the battery keeps going flat, it may be worn out, but it could also be due to a problem in the charging system or elsewhere in the electrics. Look in your Haynes manual for details of how to test these systems.