Johno02 wrote: "Would it be practical to use an auto alternator attached to a water power turbine to maintain a 12v battery bank?? Has anyone done it successfully?? To provide some power for an off-grid RV location in particular?
Yes it is possible, and, it has been done, but, for anything other than a science experiment, it is NOT very practical. You would be much better off generating a higher voltage (like 120 Volts) using alternating current when you generate hydro power. Nicola Tesla laughed at Thomas Edison for years because Mr. Edison initially didn't understand "why" either. He did eventually figure it out though.
Chum lee