So I used my Hero this morning/afternoon with music, wi-fi, internet browsing, and I used up the first half of the battery. And after that, I have been mostly studying and not using my phone... but the second half of the batter drains, it seems like, FASTER than the first half did! No music playing, no wi-fi, no internet browsing? Is this normal? Is it just the nature of these batteries? Is this abnormal for me to experience?