Guys, to be fair there
ARE DC generators in the 90%+ efficiency area, higher than most any alternator, add a pwm "regulator" or a simple contactor on/off setup and it could be more efficient at delivering power although it may not keep up at idle.
I always figured this would be a good way to downsize the alternator, have a bigger battery and integrate solar as a method of keeping the battery alive while using the least power output.
Heck control it and charge during decel
Cheers