Out-of-the-box it appears that the battery in the Rapid IoT device lasts less than a day.
I did see that the LCD backlight can be turned off, but haven't tried it yet.
Backlight_SetLevel ( BLIGHT_LEVEL_OFF )
But need to be able to put into deep sleep until a particular trigger is detected (such as motion or interval timer).
I haven't found anything like that in the SDK docs.