Tried a little experiment
this morning to see if I could tell if the alternator/regulator are working properly before I took said alternator off for testing.
I disconnected the sense wire, which is connected to the house/anchor windlass, and connected the regulator
up to the starter battery instead.
Disconnected the mains power and shut down all the electrics so there were no drains on the system at all. Just the solar panels
pumping a few amps into the house battery.
Fired up the lump and checked the voltages;
At the Alternator 14.5v
At the Starter Battery 14.2v
At the House Battery 14.2v (thruster showed 13.85v measured at the separate diode)
Leaving the engine running for a few minutes I monitored the voltage coming out from the alternator and it steadily dropped down from 14.5v to 14.25v. Fluctuated a little but no more than +/-0.5v I continued to monitor
and the alternator kept producing a steady 14.25v.
I then shut down and swapped back to the original sense wire and tried again.
At the Alternator 14.5v
At the House Battery 14.25v (this was actually measured at the diode not the battery)
At the Starter Battery 14.25v
Again as I let the engine run and monitored the voltages the alternator slowly came down from 14.5v to 14.25v with both the batteries showing 14.2v (+/-0.5v). All steady with no spikes or fluctuations.
This means the regulator
is doing it's job at the basic level at least so should mean I don't need to remove the alternator.
Doesn't get me any closer to finding out why we suddenly got the high voltages in June when this all started but at least I have removed a few variables.
So the plan now is thus:
Trace as much of the wiring as possible so as to know what is going where in the engine bay and label the wires in English
instead of Germ
Check the 2 earth cables from the alternator to the engine block. Find out where the thin earth cable goes
Over winter replace the diodes with a single
3 output Sterling ProSplitR (180amp) along with an intelligent regulator for 3 banks (2xL/A, 1xAGM). Wire the Thruster battery into the mains charger directly instead of routing mains charge through the separate diode from the house battery as it is currently. Fit a battery monitor to the thruster, wire the starter battery into my house monitor and fit an alternator ammeter at the engine controls. Double up or replace any wiring that requires it.
And don't worry I will get this work done by a qualified electrician
Hopefully that should smooth things out and keep us going for a few more years
Thanks to everyone for their input and advice throughout all this and your patience while dealing with Mr Rocksforbrains