Here is one of the nRF51822 EVK's in a demo setup … the goal of this hardware stack is to run the EVK from a single "AA" style battery. The lower of the 2 boards is a booster (actually 2) based on the Microchip MCP1640. It takes 1.5VDC of the single battery and boosts it up to a little over 2VDC. Current draw ( … on this board … ) when the nRF51822 is "off" is around 20uA; when on it's an average around 2mA. Really like these parts! 
 
We used this setup to demo a thermistor temperature probe and a high pressure stainless steel pressure sensor for an HVAC application.