Curious what you mean the BATTERY BURNED UP...
If your converter/charger is a single mode (always puts out 13.6VDC) type battery charger this may boil out your battery fluids over time and when the fluids get below the core tops inside your battery they may short out between the cores on you. This short will make the battery get real warm and also only put around 5VDC.
This and running down your battery below 50% charge state are about the only things that will make you replace your battery. My cheap standard issue 85AH Interstate batteries were installed in 2008 and are just now staring to fall off on performance. I lost one right away from being shorted out as I was not watching my fluid level. The remaining three are still in service now.
I would definitely look into why your battery "BURNED UP" what ever that means...
Two 6VDC golf cart type GC2 batteries in series makes a good setup especially if you like to camp out off the batteries over a weekend sometimes. Getting these GC2 6VDC batteries from COSTCO or SAM's are around $90 each an dwill give you around 220AHs capacity.
If your CONVERTER/CHARGER is not performing right I would get it replaced first.
Exposed batteries is probably the best way to have them but most of us like to hide the batteries inside metal boxes or inside trailer battery compartments to keep them from being stolen. Batteries are a high THIEF item. "OUT OF SIGHT-OUT OF MIND" is a good thief deterrent...
Roy Ken