Gordon wrote:
Calling all you electrical aces!
I took the boat 60 nm north to have a hard top dodger installed.
When I left the home dock, the charging rate was 13.6 and doing well.
Several hours into the trip I noticed the charging rate was down and
dropping at 12.3. Ammeter showing zilch. Turned off all electrical with
no help and continued on in. Drove up a few days later to work on the
problem, but when I started the engine, all was normal. Good current and
voltage.
Picked up the boat a week later and same thing occurred. Worked good
for first few hours and gradually fell off.
This alternator uses a separate regulator. So it appears either the
alternator or the regulator is going south when it warms up.
So which is it or could it be something different?
Thanks
G

It would help if you used proper terminology: "Charging Rate" should be
Amps, but it looks like you're giving us Volts. Both are useful, since
Voltage tells you what the regulator wants to see, and Amps tells you
how much energy is transmitted through the belt, out of the alternator,
and into the battery. Also, it would help to know what type/age of your
alternator, regulator, and battery bank.

I would normally expect an external regulator to either drop into "float
mode" after a while, which would be a bit under 14 Volts, or simply stay
at a fixed Voltage, perhaps about 14.2V. The fact that you never see
it that high sounds like you're not measuring at the battery, or have a
real problem.

In addition to the obvious regulator possibility, you might have a
slipping belt, which could appear to work when its cold, but then
essentially does nothing when it warms up and starts slipping. This
would usually fail the "sniff" test. You could also have a fried cable
to the battery - sometimes the end at the alternator can be charred
enough to fall apart when you wiggle it. This would appear as reduced
Voltage as the resistance wanders.