i need your help on this. I have this custom board build with a TMP102 sensor and a mega328, so far i am able to get around 50 hours of operation with a 850 mha lipo battery. i am sleeping the arduino and then i wake it up with the watch dog timer, the average current comsume per hour is 12 to 15 mha. So i think thats good considering is a matrix display.
How ever i would like to have it outside for ever!!!
So since is low power i think i can have it hook to a solar cell outside and when the solar cell is dead(cloudy or raining) i can power ir from my lipo battery.
I have this in handhttps://www.sparkfun.com/products/10161
and for the solar cell i plan to usehttp://www.adafruit.com/products/200
now the issue i have is the circuit to select if i will be powering with battery, use the solar panel as power or use the solar power and charge the battery at same time.
i dont know if the charger can be conected at all times and that will do the switching automatically when the solar power is dead.
if thats not the case i will need to use a voltage comparator to compare lipo againts solar cell and that will trigger to use battery? do you know any good circuits that will do this?