correct battery set up

[lowufo]

Hello boys ! I was reviewing a post I made some months back. the feed back was tremendous !! I just need some advice and some dumb questions setlled.
specs. 1975 bristol 32.
all good marine grade ( sized properly I think ) wire
all new LED lighting with very min. draw. biggest draw will be a stereo. a few hrs. a day when onboard, mostly oil lamps ,no frig,or water pumps for now
99% hook
50 amp alt. running off a westerbeak 21
seperate 12 V marine start battery
planning on 2 US 2200, 225AH bats. for house current ,should give me @ 450 AH's $ 135 each in Mass. !!
Vintron 600
Questions: aside from charging the batteries w/ the alt. for short periods of time not realizing 100% charge. what would be a efficient (cheap )solar set up to keep the house bats. up ?
If I wire the 2, 6V bats. in parralle ? to get 450 ah . how do I get 12 V down stream ? (very confusing to me)
my biggest concern is keeping the house bats up.

thanks for all you wisdom in advance

your humble student

[earlylight]

Simply put:

Two batteries wired in series will double the voltage, but the AmpHrs will remain the same as One of the batteries. Two batteries wired in parallel will double the AmpHrs but the voltage will remain the same as One of the batteries.

[lowufo]

thanks guys
I thought that was the case, but read somewhere that someone did something at the isolation switch to go back to 12 v ???? This set the confusion in motion. So my best bet ,if I understand this now, is to wire 2 ,6 V ,225 AH in series ,this will give me 225 amps but 12 volts. and I have @ half of that to use before recharge. would I need any other stuff to go along with a 50 watt panel or can I wire this directly to the bank ?Also if I and another bank would you suggest another seperate panel for them ? Is more wattage better for charging the 225 ah bank ?
thanks for the input !
Mike

[Chris Campbell]

With a 50 watt panel you'll need a solar controller to avoid overcharging your battery - fortunately they're not very expensive - in fact when I bought my 20 watt panel they guy threw one in for free. With a 20W panel you might not actually need a controller with a 225 ah bank, but it doesn't hurt to have it there, and if you add more panel later you'll need it. My 20W panel kept my 8D battery charged up on the mooring quite nicely - didn't keep up with daily use, but in between sails it would top up the last 10% that I never used the motor for (unless I was motoring too much, but I try to avoid that). It also, remarkably enough, kept the battery topped up all winter - with the panel underneath a white shrink-wrap cover!

I plan on getting another 20W panel for my current boat - I don't want something as big as a 50W panel, and for the amount of time I need to run the motor to bring the battery back up (just a few times per season), the cost isn't really justified, for me.

[mitiempo]

In Providence I doubt you will get 10 hours of full solar charging. I would figure on 5 to 7 hours at full output.