Explain jump starting from a started car is bad for your bike

[bluesjr]

Wouldn't the dead cell be more likely to be on the bike battery? I don't think most would use a busted car battery to jump their bike, would anyone? So given a full car battery and a dead bike battery, even with one cell out, how would that create a hazard to the car battery?

Haven't been following this since I posted, but yes, we're talking about jumping from a good car batt to a dead moto batt.

If the moto batt has a cell shorted (~10V remaining), the higher-volt car batt (~12V) will be dumping current into it trying to bring the moto's voltage up. Not nearly as harsh, but in effect, like shorting the car battery to ground. The short pulls too much current out of the car's battery. At least this is how I imagine the damage to occur.

And btw, to return to a point (load) that has been brought up before. If there's no load, current doesn't flow.