Thank you for the advice. The converter looks pretty old school. Magnatek series 6700 Model 6720. Also learned the battery is an EnerSys DataSafe 12HX330 Sealed Lead Acid Battery 12.0v 330W/Cell 15 min. Flame Retardant. This is what the sticker on the side of the battery says. Seems like a strange choice for an RV battery (looks like it’s meant to be some sort of back up system for IT applications)
I also talked with the guy who built it out. He says he just kept it plugged in during the winter (used it occasionally as I plan to do).
Any additional thoughts?