I have a 5V Pro Mini Arduino I intend to connect to a 3.7V Lipo battery trough a step-up board (http://dx.com/p/lm2577-dc-3-5-18v-to-dc-4-0-24v-voltage-step-up-boost-module-red-154906
I would like a LED to be lit when the battery is getting empty. Can I connect the battery to an analog input of the Arduino trough a resistor and detect when the value decreases under a specific voltage threshold ? Or is there a better way to do it ?
Thank you in advance.
That should work, and there is no real reason to use a resistor as a analog input pin is high impedance and will not draw any significant current from the battery. A reading of 3.0vdc is a generally used common value to stop drawing current from the lipo cell to prevent cell damage.