Well, during the first few days, my battery would lose about 4-5% over night. However, last night it lost about 75% overnight...just laying there on my bedside table. The only difference was that I left the wifi on. Would doing that cause such a drain on the battery? It seems kind of inconvenient to have to go into the settings and turn on wifi every time you need to use the phone. I don't remember it ever being an issue with my 3G.