I was reading Marc Kurth's post on another forum and when I clicked his name, I wound up here. so I am going to ask my question to him or anyone else. I need new Deep cycle for my RV, I don't want wet, so looking at 12v agm, lifeline is tooting their wedsite of having advanced agm, and Marc says he sell concord xtender/lifeline and they honor warrenty. I see only 1 yr of concord but 5yr pro rated and 1 yr free replacemeny, so I am trying to justify that both these cost 2x what I can get of other brands, like NPP, now I heard there are only 2 places in the USA making batteries, so I am confused. any input? anyone?