Well my WF-9855 converter is behaving just like everyone says, no bulk charge available regardless of SOC. And as usual it's gotta be the garbage factory wiring, it's 20+ ft. to tongue mounted Interst...
I totally gave up years ago on 6v battery's. I use 2 12v wired with a marine style selector switch. Less expensive and 10 times more reliable for the 70 or 80 days a year I boondock.