My battery died a lot but a friend showed me this trick. If you go into the menu and hit the 0 (zero) button a screen pops up the code for that screen is 00000 Five zeros. From that you go to network select, then mode preference. Then go to your last option 1x only and the battery lasts all day.
The problem with this is that the vcast will not work. If you want to use vcast you can just switch it back.