The Alternator is a Valdo from Turkey (60A 24v), it was on the boat when we bought hear, I assume it's the original one as the 12 v alternator also is a Valdo (60A 12V).
The problem I think is that we have a "dump" regulator and not a smart one, the only smart regulator I have found in Greece are the Sterling one, which I have heard mixed verdict about, so hesitate to purchase one.
I had the alternator overlooked at a local workshop who cleaned it and change the bearing etc, he said it work fine. what does mean?, he could not supply any smart regulator unfortunately. now it start to charge at 1800 rpm and give good amps at least in the beginning. If I reduce rpm it still charge but Amps goes down rather quick. We have had rather good charge rate on our batteries most of the time as we have the solar panels, but still it should start to charge at least at 1300 rpm.
Paul on S/Y Kerpa SM#259