Welcome to , iRV2.
Sorry you're here with problems.
From your description , the converter/charger is doing it's job, powering the coach when plugged in.
Battery power how ever is not getting everywhere it should be.
Was this a problem before the batteries were installed?
Any chance a power wire was left off the batteries or that there is a bad connection at one of the wires ?
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.