It was going strong for 13 years -- then we replaced it jut because. It's probably going to be working for the guy that installed the new battery for another 5 years ;^)))

I'm not as sure about the deep cycle Optima's -- I have Lifelines which last about 6 or 7 or years before I replace them, because...

We are very consciensus about not abusing them. We haven't "conditioned them" -- we just use a smart charger. We have a Mastervolt Combi. While I have some issues with Mastervolt, they make a great product. Before, our Heart (Zantex) 2500 before it seemed to work okay. (It wasn't a true sine wave inverter.