One of LIfe's Big Mysteries
On the journey along the US ICW and through the Caribbean we found that, and particularly when motoring, the batteries did not charge very well. We might be motoring for six or seven hours yet, at the end of the day, the batteries had not charged much. When stationary and the sun is shining the batteries would show a fairly healthy state of charge, but if not sunny, we would have to run the gas generator. So I sought the assistance of Mike in St Marten to, not only sort out the AIS/Navionics set up but to also trouble shoot the whole electric charging system.
Keep in mind that, when stationary, the fridge and freezer were operating 24 hr each day drawing, on average, about 5 amp hours. When sailing/motoring there is an additional draw from the auto pilot, say 3-4 amps depending on conditions. And at night time of course there is no charge coming into the batteries.
So, Mike started with the solar panels. We found on a mid sunny day that the solar panels were producing around 16 volts each (should be 18-19 volts but still reasonable). Three, spread over the arch, are hooked up in parallel. On checking the wiring we found that there were two places along the cable where it had noticeably overheated. Mike fixed this by cutting out about a metre of this cable and joining another (thicker) wire to the original cable to fill the gap. Worked much better.
Next we checked the charge when the motor was running and the alternator was doing its thing. The smart regulator showed that it was all okey on startup and shortly thereafter, so all seemed good. We even tried the spare smart regulator to see if that improved things – according to Mike it did so I left it connected.
All seemed to be looking good and we departed St Marten and headed south/east. Along the way ie a day or so later and while motoring between Nevis and Deshaies (pronounced day eh), Guadeloupe, I found the regulator had stopped working ie no lights showing at all. I did not stop as the engine continued to run normally and we were pushed for time, plus the seas were quite lumpy and uncomfortable. We stayed for a few days on a mooring in Deshaies, so I tried to fix the problem with the regulator, but without success. I even tried to wire the internal regulator of the alternator (which is available for this alternator) but that did not seem to work either.
We pushed on to Pointe-à-Pitre, Guadeloupe where we were to be joined by my mate, Lawrie, from Oz, who just happened to be an electrician, computer nerd and self-made vehicle mechanic. He wanted some work to do but he walked into a bit more than I think he anticipated and indeed was challenged.
After many hours of checking this and that, wires, terminals, multimeter checks, on engine, alternator, regulator, owner manual(s), fatigue, blah blah blah almost by accident, Lawrie found that the power cable for the regulator was loose at the fuse. He found this by jiggling the wire while the motor was running and the regulator was not showing any lights. Simple, and with a bit of fiddling of the fuse fitting so that it was much more secure, it has not failed since.
Next problem. When running the engine our battery monitor would show 20 amps, say, belting into the batteries for about one minute and then followed 3-4 minutes of negative power flow ie no positive amps and just a few amps leaving the batteries. This had us completely baffled and much checking (as above) followed. Finally, Lawrie jiggled the excite wire and the AC tachometer wire, which were part of a plug assembly joining the regulator with the alternator, and low and behold the problem became obvious. The plug assembly was intermittently connecting/disconnecting. The fittings were made more secure and so power to the batteries became consistent ie starting with 20 amps and lowering as the batteries became more charged but always positive current flow into the batteries. Much joy and celebrations followed, the engine charging problems, when the engine was running, appeared to be finally resolved.
That is, until we cruised into Carriacou, Grenada from Mayreau. As we came to anchor, there was a nasty smell of burning electrical insulation/cable coming from below. It sort of went away when we turned off the motor and could find nothing obvious, but the smell lingered.
A couple of days later, when we motored into Clarke Courts Bay, on the southern side of Grenada, we checked more widely and thoroughly, and found the alternator wires, where the excite and tacho wire entered the alternator, had melted. Lawrie then resurrected the old alternator, fitted it, and then everything worked (again). (Clearly we've been keeping our visiting crew very, very busy this year!)
So, in September (2023) and on the hard in Power Baats Yard in Trinidad, the ‘new’ alternator is in the repair shop and the old one is still fitted to the engine. When the ‘new’ one comes back, assuming it is healthy, we will refit it and the old one will go back to being my trusty spare.
What caused the overheating/meltdown on the alternator remains a mystery!
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