I took my battery back to Walmart. They checked it and it was reading 0 volts, and only 12 amps ( on a 600 amp battery ). So they said it was dead.
I exchanged it and went back to boat, where I found out that the previous owner did a shoddy wiring job of the soar charger, and the wires were completely dissconnected under the floor betwwen the hull and the wood floor.
That leads me to believe that the reason my lights were getting dimmer by the day ( when I used them ). was because I was using the battery with no charging going on.
So I fixed the wiring, taped up everything very nicely and checked the solar charger, and now evertything is on working order. Woohhooo.
We went sailing today in light winds and had a great time.