The
WF-8955AN is a 3 stage converter and should be capable of being left plugged in without damaging the batteries... unless there is something wrong with it.
You did not state when the previous owners replaced it, but they do have a 2 year warranty on them.
I had the same converter in my camper and it died a few weeks outside of the warranty period and WFCO replaced it anyway. I sold the replacement to a member on this board.
I had decided to buy a different converter and bought a progressive Dynamics motherboard unit (
PD4655 MBA) that fit into the WFCO power center and have had zero issues with it being plugged in all day, every day. You do need to check the levels in the batteries regularly and fill with distilled water when required.
I bought a really neat
system for filling the batteries up, from a gallon jug.
-Brian