jump starting a car

[phil on a fazer]

Walked into one of the offices at work today to be greeted by three woman asking me how to jump start a car (its because 1 of the had a flat battery last week).

So...i told them.

They then showed me some sites that they were looking at and asked why they show the jump leads being connected in different orders.

im pretty sure they were looking at these sites, (they all show a different connection order!!)

http://www.halfords.com/webapp/wcs/store...eId=851420

http://www.theaa.com/motoring_advice/bre...leads.html

http://www.wikihow.com/Jump-Start-a-Car

this got me thinking........i've always done it the halfords way. (strating with "+" on the flat battery). ive always let the batteries settle before starting the donar car (and letting it idle).....but am i right????? its always worked 

[Lawrence]

I don't think it matters that much as long as you're careful not to short stuff out and get the polarity right.

[goldfazer]

Connect -ve last, disconnect -ve first.

Reason being that if the earths are connected, and you touch car A with the + of car B, it will be very bad. If the -ves are not connected you'll be OK.

So minimise the time when leads are flying around that this can happen.

[chaz]

the important part is that you connect the neg last away from the battery as you can get a spark as the last lead makes the circuit and more so as it's disconnected, batteries produce hydrogen gas which can explode.
I had a battery explode on my starfire, due to overcharging, the zener diode had failed, and a friend blew the battery on his range rover jumping a car off, he was at home near a tap so washed the acid of his face and was ok but the damage it did was expensive, thats only twice in 40+ years but twice too much.

[Skippernick]

Connect positives first then negative terminals and disconnect in the reverse order. You only get sparks from the positive terminals.
Well thats the way i've started hundreds of boats in varies guises and never had a problem.

[Skippernick]

Having now read the links, i still stand by what i said, but i always thought the problem with newer cars was the electrics of the cars when disconnecting so the AA's advice about letting charge and disconnecting when both are off is a good idea i guess.

[goldfazer]

'You only get sparks from the positive terminals.'

Better tell the electrons, cos they don't know about that one

And not much hydrogen from a modern sealed battery either!

[Skippernick]

Well it worked fine jump starting a yacht ankle deep in diesel and petrol and i'm still here...... i think