Excess power
Hi Ted,
I don't know what the original electrical system on the 38-200 is like but there are a few key questions you should consider. It sounds like you spent this past weekend evaluating your current system? I have the benefit of several conversations with the electrical engineer, who I bought the boat from, about the electrical system he installed. Below seems to be the essence of the initial thought process.
1. How many batteries are you planning to carry around?
2. How often do you want to have to run the engine for charging? (or, How fast do your batteries get down to 50% charge when your do your normal "cruise stuff?")
3. How long do you want to run the engine to charge your batteries?
Actually, he may have started with "Darling, what modern conveniences do we have to install to make you happy on an extended cruise?" That would have changed question one above to "Where am I going to put all those batteries?"
I have happily inherited a pretty good, but complex, electrical system. The engine battery is a gel cell and it charges through an Alpha regulator off the standard 50+ amp alternator. Mine is a Prestolite 51 amp replacement. The house system has four 100 amp-hr AGM batteries in two banks. They charge from a 190 amp alternator (see the lower alternator in the picture) and a second Alpha regulator. I think this one is a Delco, but it has no external marks on it. Normally, the large alternator is de-energized. When I need to charge the house batteries while away from shore power, I have a power switch for the second regulator and a switch for the alternator (field current switch, I think).
With an Adler-Barbour refridgerator, 12v incandescent and fluorescent lighting at night, the instruments running when anchored, anchor light at night, it takes about 2 days to get into the 50% discharged state on the house batteries. It takes two hours of engine running to charge the batteries back to full. I've seen the house banks take 80 amps initial charge from the 50% state.
I have an out of production three-bank battery monitor that counts amp-hr cumulative consumption, which is very useful. It also has charge and discharge current readings in addition to voltage. I carry a Xantrex regulator for a spare.
P.S. The water heater peeking over the motor is 12 gallons.