Mobile (APN) control is not working on Android 4 (Ice Cream Sandwich) unless app is installed as system app (which is only possible on rooted devices). Reason is that WRITE_APN_SETTINGS permission is available only for system apps.
Currently I have no plans to fix issue unless google provides public API for controlling mobile data connection instead of changing APN settings.
Controls selected connections to save battery life. Connections are disabled when screen goes off and enabled back according to your settings. There are several options provided to customize connection control.
Check screenshots for options.
If you don't find this application saving battery enough, try with different options, e.g. increasing poll interval.
Note. Mobile (APN) is disabled by adding suffix to preferred (active) carrier's apn and type. So, if you select from option "Enable connection": "Never" then you must manually remove this suffix or you can always change "Enable connection" option to something different and let application remove suffix automatically when it enables connection. Option "Never" is just included if someone finds it useful.
Application will also start automatically after system reboot.
Mobile (APN) control is not tested widely with many different devices, so in case of problems please report also your device model and Android OS version.
Note! In battery info section, estimated time left is inaccurate at the beginning but gets more accurate over time.
You can also suggest new features. I will try to implement them whenever I have time.