I have bought the latest ipod nano 8GB about 2 month ago. I use it in my car to play music, however i have been measuring the average amount of time it takes before the batter goes from saying fully charged to red is like 5.5 hours. Isn't it supposed to be like 24 hours of music play? Does it affect my batter THAT much from the fact that every 15-20 minutes, i shut off my ipod once i get to my destination?