One fact that is either overlooked, or maybe not known at all is the stability of the output of the alternator VS the generator. Since the charging current is broken up into pulses several times a second by the commutator of the generator armature as it passes under the brushes, the generator produces a very "dirty" current flow when viewed on the screen of an oscilloscope. Back when the most sophisticated piece of equipment on a vehicle was a tube-type AM radio, charging the battery with pulsating DC current didn't present much of a problem. Now, with the possibility of having all sorts of fancy electronic devices onboard is present, an alternator is the obvious choice for anything other than a truck that competes in car shows where numbers-correct originality is important. Just don't get tempted to use one of the horrendously expensive fakes that try to put an alternator into an original-looking "generator".
I don't know of anyone who would want to subject a smart phone, a GPS, electronic ignition, or a fancy sound system to the choppy output of a DC generator. Solid state electronics don't play well with that kind of signal.
Jerry
