new problem to my 3gs

now my iphone sometimes charges from 10 % to 15% on 1-2 hour :/ something wrong with this, and sometimes the battery draining is fast and sometimes verry verry fast . so can i downgrade to ios 5.1.1 without shsh blobs . i was on cydia and i have only shsh for ios 4.1, 4,1,5 , 4.3 and a bit more but not for ios 5 :/ so waht can i do to get down from ios 6 , it gives me only problem