This message was posted on behalf of Intel Corporation
Hello Thomas Kirven,
Thank you for interest in the Intel® Edison Breakout Board.
Have you tried using the “battery-voltage” command? Just type “battery-voltage” at the command line with root access.
If you already tried that, you may want to check this link which shows a software-oriented alternative https://github.com/cjo20/EdisonVoltage.
It looks like the battery-voltage command is used for batteries on J2 and the github link does more or less the same thing. I was wondering if there was a way to check the voltage of an 11.1v battery on J21. I did try the battery-voltage command but that just gave me a reading of 4400 mv which I believe is the default reading if no battery is plugged in.
Looking at the schematic for the breakout board:
I don't see anyway of measuring the voltage on J21 becuase it is not connected to any kind of ADC.
It is connected only to the Power Management Chip, U37 and it doesn't have any way of communicating with the processor.
I think your only choice would be to build a custom ADC board and fit it between the battery and J21