SID

Jump starting a vehicle

Chances are you’ve done it yourself, seen someone doing it, or at least held a set of jump leads in your hands at some point in your life. The correct use of them, however, is not as straight forward as you might think, and we recommend you follow the guide as set out below.

Generally, jump starting a vehicle is a pretty safe and straight forward procedure, but remember the following points for your personal safety:

Jump starting a car
  • Don’t smoke or use naked flames - batteries give off flammable gases and an explosion could be the result.
  • Keep any metal objects away from the top of the battery - watch straps, rings, tools, etc, could all cause a spark, and that in turn could also cause an explosion.
  • Make sure the jump leads are in good condition - damaged clamps or conductors can result in overheating and can cause a fire.
  • Keep your hands well away from any moving parts like belts or pulleys, and avoid loose fitting clothing like scarves or neck ties.
  • Don’t ever try to jump start a battery that is damaged or leaking acid!

OK, you’re ready to charge - now what?

Before connecting any leads make sure the vehicles are the same voltage - differences can especially occur between differently sized vehicles. Ensure that the handbrakes are on, both ignitions are off, and that the vehicles do not touch.

  1. Connect the red jump lead to the positive terminal of the good battery, and to the positive terminal of the flat one.
     
  2. Then connect the black lead to the negative terminal of the good battery and to a suitable earthing point on the frame of the other vehicle, not to the negative terminal of the flat battery. Make sure this earthing point is away from the battery and fuel system.
     
  3. With both leads in place, wait a few minutes for the voltages to equalise before starting either vehicle’s engine.
     
  4. Start the engine of the donor car and let it run for a minute or two. Then, with the donor car’s engine still running, start the engine of the other car and leave both running for at least five to ten minutes - fast idle will do, no need to rev it up to the redline. Don’t remove the the jump leads when the engines are running - serious damage to either car’s electrics can be the result. Should the leads get hot, then switch off both engines to avoid a possible fire.
     
  5. Turn off the ignition on both vehicles and disconnect the leads in reverse order to the way they were connected. Take care not to touch the clips against each other or against the car’s bodywork.


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