Likely a bad batt, possibly from over charging, and possibly a bad cell or two.
From my experience, if a cell goes bad, your converter will just run and run and run, as it will not detect a fully charged battery for the converter charger to stop charging. This causes the batt to get real hot, boil (cooking the battery), and leaking, ruining your batt more. Checking your batt fluid and health monthly is a best practice on wet cell batts. Only use distilled watter when topping them off.
If you have not messed with your wiring, or created some situation where you are grounding out to cause fuses to pop (coroded wires can cause this), I would check/replace the batt. Maybe go with two 6v's if you only have one 12V now; my preference is 4 6V batts as I dry camp alot, others may like 12V as their preference.
Batt maintenance is easy after you do it a couple times, and takes less than a couple minutes. Also, be careful with batteries, as the gasses are flammable, and can explode in certain rare instances, which I have witnessed. This is why the batt box in your rig should be used as well as the vent hose, and no spoking during batt maintenance. A given, but should be emphasized.
Good Luck, I hope you sort it out.
2014 Voltage 3818 (Epic I & II)
2005 Fleetwood 31ASV BP Toy Hauler
2017 Ram 3500 Longhorn DRW, 4x4, 3.73, Aisin
4 Seat Long Travel Sand Rail, 97 Jeep TJ Rock Crawler, 68 Roadrunner, Various Quads