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...
Put a voltmeter across the battery while it is hooked. It possible your converter is over charging the battery. I had that happen to my motor home. I woke up one morning to the gas detector going off. Traced it to the battery, felt the battery and it was hot. Put a voltmeter across it and it was over 16 volts. Had to replace the converter.