Having a sort out in the shed and seeing the jump leads, I pose the question.... In the unlikely circumstance that a modern car (my forthcoming Yeti, in particular) should get a flat battery, would you actually use the leads these days? In days of old when men were men and sheep were nervous you wouldn't have have given it a second thought, but now, with all those fancy electronics, I'd be afraid to connect them for fear of frying my pcbs. There are instructions on the pack regarding the cor