You may well be right Rich but in my own experience, on both sides (user and designer), consumer electronics are just about bullet- proof. Typically, if one does the worst thing imaginable, say for example installing the batter backwards (electrically, not mechanically), there are shunts and diodes all over the place to protect all the major components from any damage. So as a general rule, I find almost all consumer- available electrics and electronics to be pretty robust, even in the face of determined..... silliness :-) Even w/out a working battery in the circuit, the voltage regulator will still be working, and besides all that, jumping any 12 volt vehicle from anther 12 volt vehicle, running or not, is fine in my opinion and IME. It is not about the current coming from the 'big truck' say, it is all about the voltage, and no matter the size of the vehicle, the voltage will always be limited in the primary source (big truck, backhoe, whatever).
That said, of course at some point, and I think this person is there, your advice to 'stop' is certainly sound and prudent. It seems to me that there is enough evidence pointing toward the battery, as several of us suspect, that it IS time to stop and just get a new battery. But then again, the OP said he was going to do that before I posted so I was just basically re- affirming your and others' opinions that it was the most likely thing.
As far as two or more devices, again, if all are voltage- limited, they can all be connected at the same time. The typical thing is a batter charger / staring jumper used to start a vehicle and leaving it attached and engaged while the vehicle's alternator kicks in which happens immediately when it is started. So the electrical system is being fed by two different sources but because both are voltage- limited, no problem. The same thing would go for three devices; as long as everything is limited to, say, ~15 volts, no additional current will flow into the motorcycle system (or lawn mower or anything else).
So generally, I am not really wary of mixing vehicle wiring systems to get one going, or charge the battery or anything else. In fact, if I do have a weak or dead battery and use my charger / starter booster to start that vehicle (from snowblower on up to backhoe), I usually leave the vehicle running with the battery charger connected to increase the current charging the battery for a few minutes because most or all vehicular charging systems just do not produce enough current at an idle.
Brian
and with nowhere to bleed off the power, as the battery can't act as a buffer... bad results will occurr... no?
I'm no genius, but some of these things kinda scare me...
pushing juice into a system like this, with 2 separate power generating devices (one at an extremely higher rate, the truck), for 20 minutes...can't be a good thing.
