Digger wrote on 11/17/10 at 20:27:30:dasch wrote on 11/15/10 at 05:16:14:?? If there was anything to fry in the receiving vehicle's system - you would've fried it with the original battery. Or you will fry it with donor shut off. Makes no difference to the receiver whether donor is idling or not. If anybody can scientifically prove me wrong...
No science, but it seems obvious that, by having the cage idling during a jump, you are exposing your bike's vulnerable electrics to the whims of the cage's voltage regulator (possible voltage spikes and such). How lucky do you feel?
This is not a problem, however, if the cage is not running. Ain't no way a quiescent 12 volt battery is going to harm your bike during a jump, even if that battery is as big as a house.
dasch wrote on 11/18/10 at 05:23:19:Vulnerable?
Cars have even more computers and controllers than our LS. Much more. The question is - what kind of selective spikes and surges would hurt my bike's CDI and leave entire car's electronics intact??
Well.....case in point:
A few years ago, I was rat-racing through the Gulf area on my ST1100. The battery was old, so I was not surprised that the bike would not start one hot day after a fill-up.
The only cage at the station was an old, beat up Ford pickup.....70's vintage. I asked the old gentleman in the cab if he could give me a jump (I always carry a small set of jumper cables when I'm traveling on one of my bikes).
When he popped the hood, it was not a pretty sight. I kindly asked the owner if he'd mind shutting off the engine while I jumped my bike. The ST started right up, and I was not worried about the possibility of the Ford's voltage regulator being dodgy.
So, I see it this way: If I take a jump from a running cage, there is perhaps a 1 in 10,000 possibility I'll have a problem. If I take a jump from a non-running cage, there is a lesser chance that I'll have a problem. The hassle factor of jumping from a non-running cage? Zero.
Therefore, prudent risk analysis dictates that I jump my bikes from non-running cages. There's just no reason NOT to, and there IS a reason (however small) to do it this way.