Bought a battery 3 years ago from some battery-shop next to the road for K9. Cost me like $80, it did have a warranty. Don’t remember the brand since it has been working well from the day I bought it. The lesson? Some of those batteries last, some don’t. I suppose the more expensive batteries last longer in general, but there are only so many factories that actually make batteries and quality is what is it. My -97 Fat Boy is on its 2nd battery, -11 CVO has original, -03 Chopper is on its second. None of those have been expensive, just “ sell me reasonable price battery for my...” K9 destroyed a battery on road trip, but it was because erratic VR...
I guess if your batteries don’t last, check the charging current cold, hot, idle, with some rpms... I also keep the bikes on intelligent charger if I store them for over month...