jfalsone wrote:
After over a week cruising the Ches Bay I've learned a lot about the T37 and my requirements. On the electrical side, clearly 200 AH were not enough as emphasized by Dometic. I could only achieve a full charge off shore power and this seems adequate for perhaps 2 days of use at anchor but will bring the batteries down to 50% / 12.2V. I'll qualify this by saying that my first two days were colder that normal so that reduced frig consumption some. While we were blessed with some great sailing weather (sailed a ton!), we still had to motor some through creeks and it is clear that my charging system is not capable of giving the batteries a full charge. Whereas my shore power charger will put about 14V and 10-30+ amps in, I found that my alternator/regulator system will only allow about 13.3 and the amps quickly draws down to well under 10 amps. In fact, while running the engine there are times where I'm negative on amps when the frig kicks on. I find this very frustrating! I don't have the particulars on the regulator but will find out but I'd be surprised is it was anything other than what came with the boat.
On the frig, I have some 1" insulation on the lids but will upgrade to 2" and add some seals. Not sure what people use for seals because the lids barely close flush as they are now without them. Suggestions welcome! I had added rubber drain plugs. I will look into the fan. Copy @Velera on the two banks. Need to check this but I think I can isolate the batteries now. Looking for the most sensible solution that doesn't break the bank.
For seals I used some of that rubber seal that you see on a refrigerator door. It is sometimes sold as window seal in hardware stores. It has a sticky back and comes in a coil and you can position it so that the doors close completely. It is an oval rubber or neoprene extrusion that is hollow. Works great.
As far as you not getting a full charge, I am not clear if you have a "smart" three stage external regulator. If you are using one, you might re read my previous post. The problem with these suckers is that most of them are programmed to radically taper the charge output as they sense your batteries are getting close to a full charge. So, unless you run your engine for 4 hours or more, you will never get a full charge on your batteries with a smart external regulator. So it is not the fault of your alternator if you have this kind of regulator and a large bank. The reason they design them this way is to prevent over heating the batteries and gassing them by putting a full 14.3 volts (or more on them) when they are close to fulling charged. Yes, it saves batteries from over charging and heating up, but it also can take a LOOOOOOOONG time for you to charge that last 10% of your capacity. If you are using a standard internal regulator you can ignore all of what I just wrote here.
I really have to question whether external regulators are not more trouble than they are worth for the average weekend and two week vacation boater. I hope someday to corner Nigel at a boat show if we are not both in nursing homes at that time and talk to him about this.
Ray