"CCred68046" wrote in message
...
Clamp it with a Zener Diode somewhere on the 12v output line. All excess
current will bleed off.

Thanks Clams,

I know I could regulate it easily. You are an old Merc fan and you know
how to
fix it so you must have run into this before. What I am looking for is
the
reason its doing this now after it ran fine all those years. Everything
is
still in spec electrically. I really find this interesting. All the posts
on
the web about it and no one can or has answered it yet.


The biggest reason that voltage climbs so high on an unregulated system is
that the battery is too small a capacity, and/or is a sealed or "maintenance
free" version. You want a "flooded cell" battery, the largest you can fit
and afford, to run your boat's electrics. Get a group 27 heavy duty battery
and you won't have any problems. A cheaper way of regulating the charging
system is just to use an additional battery in parallel to absorb the extra
charging.

Years back we told customers to run the boat lights all the time and have
the dash lights wired into the key switch so they were always on. That also
cut down on the condensation inside the gauge faces.

Bill Grannis
service manager