The only fuse for the battery bank are the three green 30 amp uses on the PD9280 converter.
The motorhome's house batteries were never fused other than the alternator's cable going to the starting battery which may be either fused or have a fuse link to protect the alternator.
when I install a second aux battery in a vehicle I normally install a large amp fuse at both ends of the 1/0 or 2/0 cable going to the second battery.
I do this sometimes for other automotive circuits where neccsary, some DC circuits only require to be fused on one end.
DC circuits potentially becomes more volatile than AC where high amps are involved. I've seen various types of DC become instantly hot starting a fires due to high amp sparks. Protection of DC is a bit different from AC which reacts to overload differently from DC.
Anyway there is no fuse protection near the house batteries.
