I do not have full on-line UPS units unfortunately. I only have the line interactive ones. Here is the question: is it better to replace the batteries (of a line interactive unit) OR buy a new line interactive unit? Some of the units and their electronics are from around 2005 and I wonder if newer units are more efficient with power when charging and then outputting. Otherwise, I'd be happy to be "green" and just replace the lead-acid batteries. Replacing the batteries appears to work just fine and I haven't really seen anything "great" in the UPS world like 5000VA for $100, ya know? Thanks for your thoughts.
By the time you recoup the additional costs over a new battery of the new UPS by the added efficiency, you will need a new battery for the new UPS! Unless you need more capacity than your current UPS supplies, I suggest that you just replace the battery.