I just found this out - and I'm amazed at the stupidity of Google for having this setting so hidden no one would find it. I use Wi-Fi 90% of the time - at home and at work. Generally using Wi-Fi takes a ton less battery than using 3g since you don't have to have the radio connection for data usage. But did you know that the base setting for Droids have Wi-Fi turn off once your screen goes off? You heard me right - when the screen goes off so does your wi-fi connection. It turns back on when you turn the screen on. This means when the screen is off you are using far more energy using 3g. I changed the setting today and my phone is still 80% after 7 hours. Unheard of. Want to know how? Settings Wireless & Networks Wi-Fi Settings THEN press the four line button on the bottom of your phone. (the one next to your home button) Click Advanced. Click Wi-Fi Sleep Policy Change it to NEVER. Yeah, who would think.