I admit I have not read the entire thread so this might have been covered. How old is the battery? If you are at two to three years it just might be getting on the edge. At that point parasitic loads tend to count more . You might offset it for a while by getting the briefcase size solar battery maintainer at good old Harbor freight. I find the larger version more useful than the small one. Might be worth a try.
Battery new die hard from advanced. Wouldnt put it pass defect though lol since theres not rep on the quality yet been thinking about a maintainer but was nervous on which one to get lol. Any good? I know harbor freight got mixed reviews