i have an app that gives me the reading of ipod battery. every time i use the safari, or playing games, the battery percent will obviously decrease. but after that, when i let my ipod in sleep mode, the battery reading will increase (but still below the initial battery reading). then, if i use the internet or play game back, the battery power will decrease quite a lot, and then after close the app, the battery reading will raise back a bit. in short, it is like the reading is keep changing, like when i use internet, maybe the battery will decrease by 5% and when the ipod in sleep mode, it will maybe increase back by 2-3%. i try to compare it with my dad iphone 4 by playing game on it, the battery reading look constant. is this normal?