I'm using an Arduino Mega 2560 board with some custom code based on the AeroQuad code.
I want to add a battery monitor, but I think I'm missing something:
The battery monitoring is done using the analog input pins of the arduino, right? These pins measure 0-5VDC, so we need a resistor divider to get 0-5V from 11.1V.
I followed the instructions on this page:
On the electrical diagram you see a diode from Vin to the resistors, blocking current flow from the arduino to the battery. While this sounds like a good protection to have, why would we need this? The input pins do not supply voltage.
Also, what resistors should I use? My logic says to use as large resistors as possible to minimize current through the battery monitor. Should I reconsider?