Bigger is Better in Batteries
Jerry for the power requirements you have listed, I would get the biggest battery you can afford. Add up all your electronics amperage needs and multiply by the # of hours on the hook then double that A/H answer by 2, so that you don't go below 50% of your battery rating when the batts run down. I would also get a "matched" 3 stage charger. Assuming you can plug in at your slip, wire the charger into your boat electrical system. If you are out on the hook and want to replace a few amp hours get one or 2 good size solar panels. That plus what ever you can get out of your alternator will prolong your electrical bank.I would also recommend a battery moniter to guage your voltage, charging current and amp hours consumed. Takes the guess work out of it.I would have a dedicated starting batt. Does not have to be a brute , just a smallish car battery should suffice. Keep it seperate from your house bank, using a switch, or isolator.I have 2 6V 220 amp/hr golf cart batts, and a guest 10A 3 stage 2 bank charger. A cheap car starter batt, a 1-2-both-off switch, and a Trace battery moniter. Two 2 amp solar panels, and an alternator on the diesel round out my charging capabilities. Its taken a few years to assemble my system, but I finally feel I can just about meet my electrical needs. The only thing I would change would be to increase my solar panels to 2 5 A panels. Its a work in progress.I would mount this mass of lead as low as possible, to add to the stability of the boat. Also should be readily accessible. There is a lot of opinion on battery type (gell, AGM, wet), make (dual purpose, deep cycle, 6 V, 12 V). Check out the books in this forum, under electrical. Sorry for the rambling, but this is not a simple subject. Good luck with your decisions.Don