Under test ---------- LiFePo4 is a recharable battery. Nominal voltage 3.3V and charging voltage at 3.6V The maximum voltage for MCU is 3.6V. It is possible to change the voltage regulator so it gives 3.6V to MCU. This means we can connect a solar panel to V_IN and charge when sun is shining. During night/overcast etc the LiFe battery will power the mote. The diod used has 0.63V forward drop and cathode towards GND. It can be mounted close to the voltage regulator. Desoldering can be tricky. It's probably best to cut the old LP2950/3.3V and install a new one to not damage the PCB. Diode monted: http://herjulf.se/products/WSN/sensors/pictures/ldo-mod.jpg Test are done with AAA 200mA battery http://herjulf.se/projects/sensor/environmental/apple-tree-last-5000.png