There is a trio of people claiming marine batteries are good for this use. It would be unfair to reply to just one. Marine batteries are fine for this use. A t

There is a trio of people claiming marine batteries are good for this use. It would be unfair to reply to just one. Marine batteries are fine for this use. A typical marine battery might be good for 350 cycles. That should be more than enough for a UPS. (It isn't clear from the battery literature what they consider a "complete cycle", it seems like a high number for a full discharge, but even if overstated it is still plenty for a UPS). Marine batteries do have a higher cost per stored energy compared to deep cycle batteries. I don't know if that is from the higher available discharge rate or having the word "marine" in front of them. Renewable energy folks shun marine batteries because the real deep cycle batteries are good for 3000+ cycles, but you just don't need that for a UPS.