James Saulpaw wrote:
"Alternator output (current) does not change with engine speed."
Wow, I don't know how you can possibly justify a statement like that.
Alternator output varies a lot with RPM, especially at low RPMs. Once a certain minimum RPM has been achieved the curve flattens out a lot but the difference between idle and cruising or even wakeboarding speeds is dramatic.
If you would like to see what a typical high output alternator's RPM vs AMPs output looks like take a look here: http://www.balmar.net/PDF/Alternator%20Drawings/70-seriesdimensionaldrawing.pdf
Note that alternator RPM is typically up to twice the engine RPM.