I’m powering the Turner Turbidity Plus via the Mayfly’s 3.3V, and its average current draw during wiper cycles is 109mA.
Thanks for sharing your wingboard. As far as wiring, I have some of the EnviroDIY protoshields that I plan to use. I’m interested in how, physically, you connected the Vbat to your ADC for measurement. Are you using the onboard ADS1115 or an external one? Any photos you can share?
The STC3100 looks interesting. Have you found a breakout board for it, or are you a surface-mount-soldering ninja? 🙂