Transmitting lipoly voltage

Hey, I'm building a drone I'd like to control with my phone.

One of my problems now is transmitting the battery voltage level, or at least an alert the battery is low. I've seen instructables that use a voltage buzzer to do this, just by taking off the buzzers, but I want something smaller I can build into my control board.

I'm currently using a 14.8 battery with a 5v ubec to power a 3.3v avr board. I'd imagine the ubec makes it difficult to use just a voltage divider into an analog input. Can I just read from a voltage divider raw from the battery, as long as I bring the level down to 3.3v?

Thanks

Of course you can read the voltage, using a voltage divider. But I don't know whether the resulting resolution is fine enough to find out the battery loading state.

If you create a voltage divider with a couple of resistors you can drop the 14,8v to a range that is suitable for your Arduino. Then you can read the value with analogRead(). You will probably need to do some experiments to figure out what the ADC reading corresponds to and to figure out the value that you want to use as a lower limit. I suggest the total resistance of the voltage divider should be about 10k to keep the drain on the battery low. And make sure the voltage divider is sited so there is no current through it when the system is switched off - otherwise you will flatten your battery.

...R

What do you mean by sited? As long as the board is off, it shouldn't draw current, right? Or do I need to add a transistor in front of it?

Thanks for the help btw

CantSayIHave:
What do you mean by sited? As long as the board is off, it shouldn't draw current, right? Or do I need to add a transistor in front of it?

All I meant was to put it on the OFF side of the switch.

...R