I am noticing a trend more and more on my new 4s. Whenever I charge my phone overnight like I normally do the battery tends to drop quickly first thing in the morning, sometimes up to 20% in just an hour or so. However during my commute to work I plug my phone into my Griffing iTune rf transmitter to listen to audiobooks and podcasts and upon arriving to work my battery appears to be infinitely better. For example lose 20% checking email and Facebook in an hour or so compared to losing only 25% for 8 hours of audiobook listening streaming over Bluetooth to my Bluetooth headset. It is things like this that have me scratching my head.