I posted this on alt.auto.tech and got an interesting answer but thought I'd see if any of our Jeep Illuminati could expand on this question.
> I tried to jump start a Suburban tonight but I couldn't because the
> > battery's side terminal post had separated completely from the
> > battery. I hope I can convey this correctly. The positive cable is
> > still attached tightly to the post bolt but where the post bolt goes
> > into the side of the battery, it's broken completely off because of
> > corrosion. I think my jumper cables are 10 gauge and I was trying to
> > get a good clamp connection on just that loose Red(positive)starter
> > cable. I was thinking that this was all I needed to do and once the
> > motor turned over, the Suburban could be on it's way.
> > After hooking everything up, the hood light would come on and the
> > interior lights would light but I couldn't get the Suburban to turn
> > over but once or twice before the starter would begin clicking. I
> > tried repeatedly but never had enough juice to crank the motor. I am
> > guessing my jumper cables just didn't provide enough current from my
> > battery to make that big motor turn over.
> >
> > Could I have done anything else? I have heard you can put your
> > positive jumper cable on the positive end on the Solenoid and crank an
> > engine that way but I have never done it before. Would that have
> > worked or would it not have made a difference?
> > I realize a motor draws A LOT of current to crank and I was trying to
> > feed this motor with my 10 guage jumper cables. Anybody want to offer
> > their observation?
> (Nate replied)
> 10 gauge is nowhere near enough. Think about it, the battery cable to
> the starter is usually 4 gauge minimum and only 40" long or less.
> You've pretty much nailed the "problem" and the only real solution at
> this point is a new battery. If you want to jump start it you'll need
> heavier cables (I'm sure they're not actually 10 gauge, maybe 1/0?) but
> depending on the year that may not be a good idea - electronics don't
> like running without the battery to damp out the voltage fluctuations
> from the alternator (the alternator doesn't put out filtered power, it's
> just straight full wave rectified) and when you replace the battery you
> may want to replace the positive cable as well - if the connection
> corroded out of the battery, that end of the wire can't be in
> particularly good shape.
> > good luck>
> nate