I'm with Tim - I've never seen any alternator spec'd at more than 15V and would need to see some mfg info explaining the 17-20V - also that's part of what the
voltage regulator is for, internal or external, to prevent blowing up the battery
also note that turning an alternator takes about 1hp for each 25amps it can produce - if you can do fine with an 80 amp unit, why sacrifice as much as 5hp on a 200 amp? unless you want to have a portable welder along for the ride
Bill
