8V92 alternator questions

[Don Bradner]

I am home now, and will hopefully have a couple of months to get things ready
for the next trip. I had an "interesting" day, and will outline it while the
data is fresh in my mind.

We started the day in sporadic rain, that progressed to steady rain. Early on,
when I would turn on my headlights, the transmiission would flash "Do not shift"
and "Check transmission", 3 blinks, then off, then repeat in a few seconds. That
would end with turning the headlights off.

Later in the day, when the headlights were on all the time, the transmission did
not complain.

With headlights off, I had voltage readings typically like:

Analog gauge, 13.2 volts
Prosine 2000 monitor, 13.4 volts drawing 8-10 amps
Digital readout from the engine computer, regular jumping around between 12.0
and 13.2, most around 12.5 and 12.7 (via VMSpc interface)
Alternator 1 zero output, Alternator 2, 25 amps

With headlights on, after being on some time:

Analog gauge, 12.5 volts
Prosine 2000 monitor, 13.0-13.2 volts drawing 8-10 amps
Digital readout, regular jumping between 12.0 and 12.5, most around 12.0, 12.1,
and 12.3. Occasional 11.8
Alternator 1 zero output, Alternator 2, 50 amps

Still with headlights on, generator running:

Analog gauge, 13.2 volts
Prosine 2000 monitor, 13.9 volts charging at 25-30 amps
Digital readout, regular jumping between 12.5 and 13.2, most around 12.7
Alternator 1 zero output, Alternator 2, 25 amps

Conclusion: One alternator is not working, and the other is "weak." Hard to say
yet if the problems are with the alternators themselves, or with connections to
them. That will be part of the projects I have to work on when it dries a bit
(rain predicted for every day in the next week).

Don Bradner
90 PT40 "Blue Thunder"
Eureka, CA