Vehicle manufacturers design alternators to suit the CHASSIS. How many thousands of 12SI 66 amp alternators have I overhauled on 80's largest Bounders and other Fleetwood products, Southwind, Winnebago, you name it. I replaced rotors to the 7273 78 amp model minimum.
Sal is absolutely correct about voltage regulators. They use normally internal temperature compensation some of the newer rigs use ECU voltage regulator especially those with MoPar chassis. There has never been in the history of USA alternator manufacturers a FLAT COMPENSATION voltage regulator fitted to a production motor vehicle. With the 3G, 4G and 6G Ford alternators it is normal to see a .7 volt slump from 0C to 150C.
Up until around seven years ago THE OVERWHELMING MAJORITY of alternators used on cruising sailboats was a custom highly modified 10DN Delco alternator. Rotors finished cut to .012" rotor stator airgap, and Delta 12 gauge 4/3 hand wound stators - many used the 12 SI wider stator lamination stack. Rectifiers (1/2" press fit) were changed from 25-ampere 100 volt rated units to Motorola 5012 50-ampere 200 volt. These old "Lestek" rectifiers had red printing on the bottom of the can for cathode case rectifiers and black for anode case rectifiers.
Then Ford with their rectified WYE 3G alternator hit the market. It charged much better at low speeds. Any OEM alternator that uses a rectified WYE stator has EIGHT rectifiers rather than SIX.
Next, many aftermarket alternator peddlers tried the large frame older Ford 100 amp alternator, others DENSO frame alternators that are modified.
The latest generation is a real humdinger. Alternators with HAIRPIN stators much like the old 50DN Delco bus (mostly gear driven) alternators. These guys use 125 amp stud mounted rectifiers with 6 gauge leads.
But whomever made the comment that automotive technology is ice-age is spot on. IF and I mean IF an alternator is not controlled by an ECU it can be modified to accept an "A" circuit cruising sailboat external voltage regulator. Three-stage with equalization circuit. But there is a catch. Equalizing voltage is far too high to trust onboard electronics to deal with it.
Hope This Helps
