jfalsone wrote:
Thanks Valera. My system is now comprised of three Odyssey G31 100ah AGM for house bank and one G24 AGM for start/reserve. I will be installing 100W solar but may add later if it makes sense based on useage. I just finished rewiring it all. I'm using a Blue Sea ACR between the banks. My new alternator is Compass Marine and I will be using a Balmar MC 614 regulator. Mainesail tells me that with a standard W50 3/8" belt I will generate 60-70 amps (controlled through belt manager) and that my alternator will be "very happy". Of course, I want to make sure I have the right charging profile correct for best bulk and acceptance performance. My biggest load is refrigeration right now (4-5 amp intermittent I think) but I will need to figure running a laptop off a portable inverter too.
So, moderate size bank for moderate loads and external regulation. The info about your cruising experience with 3/8" belt is valuable.
So if you do the math on what you are presenting here, You have about 150 ah of usable power between recharge cycles--because you do not want to take them down much more than 50% I would assume. The 100w solar will be very valuable to "top off" your batteries from the deficit your "smart" regulator will leave (because--no matter how you set it--it is going radically reduce the charge rate as it approaches "full" voltage--look at what amps are actually going in after the first hour and what you % of charge is on your monitor--if it does not stop charging altogether from heat sensors on the alternator or battery if you have those options) but the solar will not really provide much of your basic needs. Seems like you are set up with moderation as you say and should get along nicely. I do like most of what Mainesail says, but we disagree on some of his details. He is selling stuff now and I don't blame him but it has sort of gotten him back in the retail business pushing more is better and I will never understand his love of Balmar stuff considering the number of failures he has reported--except that it is very good looking and grossly overpriced. I have met him in a Maine anchorage a couple years ago--his boat looks as nice as you would expect. If you ever want to simplify things, you could lose the starting battery. I assume your bank is divided (? or maybe not with three batteries?) in two banks. You are very unlikely to have a dead cell in both batteries and if you flatten both batteries you can get a small diesel started again by cutting out the bad battery out of your system with the switch and letting the other rest for a few hours. It will start. I have never had a starting battery in my boats in 45 years of cruising (just two banks that I ordinarily run together 99% of the time). I have flattened batteries a couple times accidentally and had a bad cell once, but no real problems.
The big thing you can do to manage power is to deal with your refrigerator demand. Not sure what you have done, but the T37 box is very well insulated except some of the tops are not sealed or properly insulated. Also, the compressor should be in the coolest place possible. In the tropics I used to open the lazarette cover over night so the thing was not fighting engine heat. Also, I put a bigger computer fan on the compressor and put a tiny one (these use much less current than the OEM and move more air)in the box to keep the cool circulating off the bottom (and put a cork in the drain so the cool does not run into the bilge). All this reduced my compressor run time by at least 30%. Froze my beer in Panama. So you can increase your electricity production or manage your energy sometimes. For most of us, refrigeration is more than half of your energy budget.
FWIW
Ray