analogRead on battery

Hi all

I'm just looking for some advice with regards to reading analog voltages when my project is powered by a 3v coin cell.

Essentially I'm trying out my own wireless moisture sensor but have a nagging thought in my head about... If my arduino pro mini 3.3v has a default vref of 3.3v will my analogRead() values be effected as the 3v battery drains (overtime) ?

I'm guessing I would need to either:

Wire up the AREF pin - so as the battery looses voltage the VREF will fall with it. or Set up a voltage divider and use the 1.1V Internal reference.

I'm I on the right train of thought?

I appreciate your help! - and sorry if this post seams rushed... I'm supposed to be working :)

Set up a voltage divider and use the 1.1V Internal reference.

I believe that will work as long as there is enough voltage to run the Arduino.

Wire up the AREF pin - so as the battery looses voltage the VREF will fall with it.

No... That's the opposite of what you want to do... ;) The reference needs to be constant & known.

See: http://forum.arduino.cc/index.php?topic=38119.0

Awesome, thanks for the responses guys!