One thought.. My Chassis battery (Workhorse branded) lasted 9 years (Same as house.. well almost chassis went a month sooner) but during that time I had several "Dead battery" like events.
Damon used common crimp on "RING Terminals" not proper battery lugs to connect to the side terminal battery. the metal reacted with the lead and a tiny amount of acid that tends to be present and corrorded somethign fierce. A quick wire brush or scraper job and good as new.
When i replaced the battery.... I replaced the terminal lug. (Wire end).