The converter to battery pos wire might already have the rig's "battery disconnect switch" on it somewhere.
When that is opened, the converter cannot charge the battery bank, but then neither can the battery bank run the rig's 12v systems via the DC fuse panel. When on inverter for 120, you are still on battery off-grid. The inverter is just another 12v load on the battery bank.
You must disable the converter by disconnecting its 120v supply (various methods for that) AFAIK the charger in the inverter/charger will not "enable" when on inverter.
