RW Salnick wrote:
Jeff inscribed in red ink for all to know:
KLC Lewis wrote:
Essie has a Model 20 Universal (5416) 16hp Diesel, fitted with a 50
Amp alternator. The biggest alternator I can put on this engine,
according to my research, is an 80 Amp.

What is the limitation? I would agree that with size of the bank more
than 80 might not be cost effective, but the small case alternators go
up over 100 Amps.
....

Aside from any physical limitations, there is the matter of horsepower -
turning that laternator isn't free you know. At 12 V, a 100 amp
alternator is delivering 1.2 kw. At 100 % efficiency of conversion
(unrealistic), this represents nearly 2 HP. At more realistic
efficiencies, this is more than 2 HP. This is only a 16 hp engine...


That is an issue, but it isn't a big problem. My alternator is on a
Yanmar 2GM20FC, which is 18 HP. When at anchor, its actually better
to have the large alternator, because it means the engine isn't
running unloaded.

Underway, it can be a issue. Since I have twin engines on my cat, its
easy to so see how the load affects both the output and the
temperature of the engine with the big alternator. If I expect to
need full power, I set the regulator to 30 Amps; otherwise, the loaded
engine won't rev up fully, and will run hotter. Also, its SOP for
the cook to advise the helm when the microwave will be used - this
will have a quite noticeable affect on the power, as the DC draw of
the inverter is 86 Amps. Thus, it would be desirable to at least have
a shutoff; would that simply be a field disconnect?

One thing I will concede: I go through a lot more belts on the big
alternator than on the small!