If the 30 amp fuse is actually a breaker and your battery positive cable is lying around shorted to ground your converter/charger is trying to charge the missing battery but is instead feeding that power to the shorted positive cable.
The breaker is probably cycling on and off enough to get hot. A fuse would burn open IF the short is a solid low resistance short but if the short is not making a good contact it could allow almost enough current to blow a fuse.
Pulling the fuse removed the short so to speak and allowed power to get to the other circuits.
There may not be enough power from your converter alone to run an awning or heavy current item. Your converter could be a real wimp and just big enough to charge the battery but not big enough to run any big loads.
The 30 amp fuse/breaker could be misleading however correct in that it is just that size to allow the battery to supply that much current FROM the battery and not sized for the charging ability.
That is probably not clear but in any case you will find the short on that positive cable somewhere.
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Certified Senior Electronic Technician, Telecommunications Engineer, Telecommunications repair Service Center Owner, Original owner HR 2008