I leave WiFi and GPS on all the time. Where I live in NY there are WiFi spots everywhere so when i leave my house or office, this thing hunts all the time until I unchecked that setting in the WiFi settings. My battery lasts between 9.5 - 12 hours on average and that's with a lot of texting, instant messenger (I use Trillian with battery saver on), web browsing, checking two email accounts etc. The GPS only goes on when A. You open your web browser up and that is for a few seconds then turns off and B if you are using Google Nav.