Look at your energy usage.
Steve, You need to determine how much energy you will need. Having a Group 24 or 27 as a house battery give you less than 100AH. This may be barely adequate if you only have VHF, GPS, and a stereo. If you start adding chartplotter, radar, refrigeration, pressure water, etc. the usage goes up. Also, if you are going to be away from shore power a lot you will need more reserve. The usual recommendation is 2 to 3 times your daily need. This also prevents your batteries from being used below 50% of their capacity, which severely shortens the life of a battery. I had a single Group 24 last season, plus starting battery. This season I am changing that to 2 Group 31s for over 200AH in the house bank alone. I am also adding a 3-stage regulator to more efficiently charge my batteries. Another thing to look at is the type of battery. An AGM or Gel battery may cost more, but they are much less of a maintenance headache (no water to add) plus they last much longer. You could also look at having a pair of 6V golf cart batteries. Each one takes up the space of a Group 27. When hooked up in series, you get 225AH at 12 Volts. These are a few options. Good luck. Les Murray s/v Ceilidh 86 C-36 #560
