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pappajohn · 12-09-2007, 06:17 PM

hi,
during my short lived apprenticeship(cant take orders) i was always told to connect the neg lead to a suitable engine/body point on the dead car LAST as, if the battery had been gassing, there was a chance of explosion if the lead sparked on contact with the battery neg. if connected to a different point it should be far enough away from the battery not to really matter if it sparked.

im sure with the advent of the ECU/EMU connecting to all terminals could cause a power surge and 'spike' the ECU, but i have my own views on this and i've never experienced it, after all, the handbooks state ignition MUST BE OFF when connecting, presumably to isolate the ECU.

the other point about not touching vehicles goes back to the days of chrome bumpers ect. if the cars were touching you already had an 'earth' connection so when the pos lead was connected this could spark and do the same as in explaination one.
plus in the days of pos earth you would certainly know you got it wrong. if one car was pos earth and the other neg earth it would be the same as connecting two batteries POS-NEG and NEG-POS.(BANG)

john.

12-09-2007, 06:17 PM	#15 (permalink)
pappajohn Member Funster No : 172 Join Date: Aug 2007 Location: scarborough, nth yorks About Me: Waiting for Tommorrow Interests: beer,tv and motorhoming MH Type: coachbuilt MH Model: swift kon-tiki Years Motorhoming: 5 years Posts: 2,382 Thanks: 33 Thanked 175 Times in 162 Posts	hi, during my short lived apprenticeship(cant take orders) i was always told to connect the neg lead to a suitable engine/body point on the dead car LAST as, if the battery had been gassing, there was a chance of explosion if the lead sparked on contact with the battery neg. if connected to a different point it should be far enough away from the battery not to really matter if it sparked. im sure with the advent of the ECU/EMU connecting to all terminals could cause a power surge and 'spike' the ECU, but i have my own views on this and i've never experienced it, after all, the handbooks state ignition MUST BE OFF when connecting, presumably to isolate the ECU. the other point about not touching vehicles goes back to the days of chrome bumpers ect. if the cars were touching you already had an 'earth' connection so when the pos lead was connected this could spark and do the same as in explaination one. plus in the days of pos earth you would certainly know you got it wrong. if one car was pos earth and the other neg earth it would be the same as connecting two batteries POS-NEG and NEG-POS.(BANG) john.