I agree with other posts - sounds like metering issue. Temperature or
moisture related?
I'd try drying everything out with a hair drier before you start the
engine - see if the problem goes away.
David
"Fred Miller" wrote in message
...
Boat and motor are both 1979 vintage but are in reasonable condition for
their age, However, in the last week a strange problem has shown up with
the charging system on the motor. After sitting overnight the engine
starts
normally but the voltmeter on the panel shows only about 9.5 to 10 volts
but
the engine seems to run well both at idle and at speed no differently then
before this began. After sometime ( 5 to 15 minutes) the voltmeter shows
13+ volts and continues to show and show normal voltage behavior after
shutting down and restarting. Even after 3+ hours off it will start right
up and show normal starting voltage. All suggestions for checking this
out
are welcomed. Fred