During a recent trip we discovered the charge on the house batteries was very slowly dropping although we were plugged into 50 amp shore power. Also, the refrigerator inverter was completely dead when not plugged into shore power. At the recommendation of the shop who services our coach, I am having to replace all four 6v wet cell house batteries (plus 2 for the residential fridge) in our 2010 Fleetwood Discovery. I am meticulous about checking the water level in the batteries every two weeks, keeping them topped off at proper levels, and keeping the cables/connections clean and free of corrosion. We do limited dry camping, and when doing so, I have never let the battery charge go below 50% (12.06 amps). The batteries we are replacing are Crown (brand), which were purchased new only about 30 months ago. It seems to me they have failed prematurely. I'm wondering if I am overcharging them. When in storage, I always have the coach plugged into shore power. Would I be better off not plugging into shore power and use the battery-kill switch? Any comments, ideas, or suggestions will be appreciated.