Its not all that unusual for a dead battery to draw alot of current to get started back up to charge. I would put back a 50AMP fuse or bigger...
The sad thing is I suspect your battery may be beyond help if it is drawing this much current to start up a re-charge. The Deep Cycle batteries don't do to good if you let them get below 12.0VDC State of Charge. They start going into self destruction after that... Lets hope you can re-cover ok...
Good luck...
Just to be sure it is NOT connected in REVERSE POLARITY - note on the battery case which terminal is labeled "NEG" or has the symbol "-". Then hand trace this connected battery cable to make it is the one going to the trailer frame ground connection that is real close to the battery. It is so easy to get them reversed... We all do it one time or another...
Roy Ken
