My Coachmen Freedom express has been plugged in since I de-winterized it in April, the battery (new in 2014) was stored in the garage (heated) over the winter. Over the last week I've noticed a sulfu...
More than likely the battery is toast. the charger is seeing low voltage and is trying to charge it. it is being charged so much it is boiling the battery. I had one do the exact same thing.
I can tell you from personal experience you do not want to be near a bad, boiling, overcharged battery! they can explode! (I know from experience). fortunately I was not hurt, but it could have been very bad!