I was wondering how safe it is to use jumper leads now to start a car with a flat battery.

Last night my son's Megane died on him and I ran out with my Mondeo 2.0 TDCi. I have avoided using jump leads since the introduction of electronic control units and other sophisticated electronic chips in case a surge damages these. However, I am not sure if I am worrying unnecessarily? I am not bothered about the Megane frying, but I would rather not lose my Mondeo. :)

Has any the cars got sensor on battery terminal

As long as you use them correctly and don't short them out you should be fine, there is a correct method of using them but not many do.

As long as you use them correctly and don't short them out you should be fine, there is a correct method of using them but not many do.

Many thanks. I assume that that method is the one described in the owner's manual?

mr AA man told me.

+ to +

Connect Earth to Earth chassis , do not start the Donor car , start car with flat battery , allow to tick over for about 5 mintes do not rev. Stop the car remove the leads.

Similar to Pree, although I was told to rev the car a little before you try to jump start, and keep the revs up to about 2k when you try to start the donor vehicle. Leave both vehicles to run, remove positive from dead car, then from donor car, making 120% sure not to touch any body or anything with the jumpers, then remove the negatives.

Jeeb , when i questioned the AA guy he said with the other car Donor car running , removing the jumper leads while running can cause it to Spike and damage the ECU.

safest way of doing it is with a slave battery, so if any doubt disconnect the earth lead on donor car... (not forgetting issues with radio codes etc)

connect the earth lead last and disconnect first

worth the extra money for decent leads...cheap ones arent worth it and often fail/cause problems

modern cars can be very sensitive and although the chances of a problem are slim and rare..it does happen

AA wrote off a fiat by jump starting a few years back, caused a spike and blew the immobiliser,system which meant new system and complete set of locks needed...was an old motor and wasnt worth the repair...but an eg of what can happen....

http://www.theaa.com/motoring_advice/breakdown_advice/using-jumpleads.html

Thanks Paul, Its odd as I had the RAC talk me through that process before when they came to my aid in the last Focus... I suppose each recovery person will have their own ways of doing things, rightly or wrongly!