Hy Kip's41, "new" batteries can sit on the shelf for months, and when they sit there wet (with acid in them) they start to go bad and lose capacity. When I used to work in a F.L.A.P.S. we stored our batteries dry, and only added acid when a battery was sold. I had a problem with a "new" battery, it came to me dead, when I called the store about it, they told me that I had to charge it, I said I don't think so, but I will try that and see how long the battery lasts. Two weeks after charging the battery and using the vehicle, the battery was dead again. I removed the battery and grabbed my small hand held battery tester and headed for the store. I explained the problem to the store manager and asked if I could load test his stock of that brand of battery, he agreed, when I left all of his stock of that brand of battery was off the shelf and waiting to be sent back, none of them passed the load test, and most of them were not charged enough to even test. If battery stock is not rotated they will go bad, I still think your problem is more battery related. Once you have a good battery you can setup your charging system as Hotrod Lincoln suggests, or you can take it to an automotive electrical shop and have it setup, if you can find a shop with the experience to work on a generator/regulator setup, hope that helps.
