Welcome to the forum and congratulations on the 8281SS!
If you are depending on the power center in the trailer to recharge the battery, it will take quite awhile. Depending on the size of the battery, it could take two or more days to recharge a completely dead battery. Even though the battery is relatively new, if completely discharged it can drastically reduce the life of a battery.
As far as manuals, there is no 8281SS specific manual. Forest River (and most other RV manufacturers) just give a basic instruction manual which doesn't really tell you anything and then a stack of manuals for each specific component from its manufacturer: AC, water heater, microwave, stove, axles, brakes, etc. Most of those are available on line, you just have to look up what you have.
Good luck and happy camping.
Glenn & Beth (Dad & Mom)
David & Audra (16 year old twins)
2006 Dodge Power Wagon (Adventure & Tow Vehicle)
2006 Rockwood 8281SS (Home away from Home)