Joe,
Thanks for the input so far. Are you able to say what the output of the 110A alternator would likely be in practice? Is 50A reasonable?
I have a conventional diode splitter with the sensing wire at the batteries on the 50A and have been getting voltages of 16.5 - 17 indicated with about 25A on boost which seems to suggest the wiring is indeed marginal anyway. I would expect 14.8 plus about 1.5 for diode plus cable maximum (?). If I fit a 110A I will seriously examine/replace the cabling but how big should it be? In am assuming for that amperage I will need 25mm2 battery lead. Also would you expect the single 1/2" belt drive to be man enough? I see the driftgate alternator is fitted with one as standard but am considering fitting twin pulleys is this OTT?
If I assume 50A at 15.5V thats 775W which is a little over 1HP assuming I have got my sums right (?) assuming 100% efficiency. 110A would be 2-2.5 HP theoretically but I think the sterling will need the trip switches re-set for the bigger alternator (I will have to look up the installation manual again) and will not allow a higher rate of charge than the batteries will tolerate which will probably be no more than 50A. Either way I will fit a switch in the activation line of the stirling to allow me to reduce the charge rate when I need maximum output of the engine to drive the boat.