Well, having only an '83 Nissan Stanza (a nearly extinct animal (carburetor & older alternator)) I’m not up on new cars, but voltaire seems not to be referring merely to a rare problem with H2, but to the interposition of some electrical component/module between the negative terminal of the battery and the engine block. If there be such a component, I wouldn’t know which side of it the negative side of the alternator output would be connected to. mr. john refers a “lil black box” but doesn’t specify where it exists in the circuit. He then implies that new-car alternators have external regulators, so I would assume the box he refers to to be a regulator. Then again, not knowing mr john, maybe the box he’s referring to is some kind of fuel-injection control circuit which has nothing to do with the jump-start task. In any case, before getting involved with jump-starts to or from new cars, with or without fuel injection, I’d want to know the possible battery-supply and charging circuits that are around these days.
Of course, there’s no way electrons (or ions in the battery) can ever know whether you clamp any given cable first to the dead battery and then to the good one, or vice versa, so that’s of no consideration at all. And if nothing other than the cables completes any circuit between the two cars, it also certainly doesn’t matter whether you hook up the plus cable first or the minus one. Mention of these concerns does make me wonder about the legitimacy of the concern shown here as to where the negative cable is clamped on the car with the bad battery. This practice is probably good in general, though, in case the “bad”-battery ground cable has high resistance and the starter on that car is also returned directly to the block, as it should be. Starting the car with the good battery first, of course, always has been the proper thing to do, and it’s usually best to rev that car up somewhat about normal idle.
Ray (EE but no expert on cars)