Gm1234 wrote:
....

My engine is a 15HP 2-cyl Yanmar and max recommended alternator is 80A. At
normal RPM with this alternator actual output at prop would be less than
10HP. I don't have power curve for the 1-cyl 12HP but I used to own one on a
27ft boat, but I have seen them on 32ft boats and then you need every HP you
can get. In that case, a means of disabling the alternator may be needed
when you NEED maximum output from the engine - there is a way to do this,
but I don't have the details.



I have a 110 Amp Balmar on a Yanmar 2GM20FC (18 HP). When I'm powering
at 3000 RPM the engine runs significantly hotter when charging. I
normally
limit the charging current to 30 AMPs when traveling if I know the
batteries are discharged. Also, if my wife wants to use the microwave
while we're powering, I'll have to throttle back a tad.

On the other hand, when charging at anchor and running at 2000 rpm or
less, the engine stays so cool that the hot water heater doesn't get
up to full temperature.