Read input voltage superior to 12V

Hello everyone,

I'm currently using an arduino uno board and here is my problem: I need to read input voltages that are superior to 12V. The problem is that in the final product I won't know the power of the battery the consumer will use. The guys that I'm working for bought me this:

http://www.dfrobot.com/index.php?route=product/product&filter_name=power%20shield&product_id=378#.UYoleCtah_c

But from what I read I can only read output voltage. So could you help me by giving some advices on how to read the input voltage with or without the power shield. Or by indicating me new boards that could be more useful.

Thanks a lot for you help :)

That shield is a DC-DC converter. It will make a voltage of 1.25-12V for a device that requires such a voltage.

Reading a voltage is done with two resistors in series as a voltage divider. http://arduinotronics.blogspot.nl/2011/03/monitoring-voltage-of-dc-battery-supply.html

For example with 100k and 10k. The 10k to ground. The 100k to the voltage to meausure. Connect the resistors and feed that to an analog input.

You will be able to read 0...55V with roughly 100mV accuracy (50mV accuracy in theory).

Thanks a lot. It worked for me. I had already saw that link but I wasn't sure of how it worked. Thanks :D