New batteries

I have a Grand Design Solitude that is about 9 months old. We returned from a two week trip, did not dry camp, so the 5er was either hooked to the TV or on shore power for the two weeks. When we returned it to our storage spot, I was tired and did not throw the disconect switch I installed, the factory disconect left too many things connected, so I installed a disconect to kill all power. A day later, we returned to finish picking up and getting everything straightened out, I was able to extend the slides, but when I atempted to pull them in, the battery died! Today I replaced the 12 volt interstate with two Optima blue top batteries. Hopefully these will last longer and provide better service. Also, I had to remove the battery box, when I did there was an awful lot of corrosion dust, yellowish powder, all over the place! I thought I was cleaning and keeping the battery in good shape!