need some expert battery advise

[BrianG]

I know everything can fail, but having three V3's fail in a row where reports of even two in a row is extremely rare (if any), I would start looking at other things. Maybe there's something you are overlooking? Are you geographically located near someone here that can help you out? Not saying you don't know what you're doing, but sometimes it's nice to get a fresh perspective.