So I have a 3s 800mAh that I would like to use to power my arduino uno, but at the same time I would like to use one of the analog pins to monitor the voltage. Is this possible? Also, I know the maximum current the arduino input can handle is 40 mA and I'm scared that hooking it up will fry my board. Is there a way I can calculate how much current will flow through if I connect a fully powered lipo at 12.6V to my Uno (would Ohm's law be the right track? If there is a resistance value for the Arduino's input?). Thanks in advance for all the help.
would the voltage divider be wasteful in terms of energy lost in the resistor?