Soil Humidity - any ideas how to fix the values?

All right, it seems the watchdog does not really work for me. I've got the final code up here:

https://gist.github.com/anonymous/9706137

I had to reset the device manually twice this morning and it just stopped again.

Here is the procedure so we can rule out all other issues:

• transfer the code
  
• save() -> init is called and it all starts
  
• it is then in debug=true mode - I watch it a few times and then do
  
• debug=false and save() again
  
• I then disconnect from the mac/pixel and reconnect to the USB power supply. It works nicely for sometimes a few hours, but the secodn time it just stopped just after half an hour...
  
  

How could I get more info and data if it's connected to a power source?