Pi PICO W on batteries

The errors are very predictable as they are caused by certain very low value capacitors in the switched capacitor adc having incorrect values. It seems that the chip design tools did not model stray or fringing capacitances accurately enough. There is software around that can post process the adc readings to make a substantial improvement.

Oh yes. It has noise allright. But feeding sensors from the stabilised

Do I really need 12 bit accuracy to measure temperature? Not really. Nor is it a microsecond sample that I need, Ring buffers and averages are easy to implement

Onboard is fine.

I saw a video couple of weeks ago, there's a new release of SDK that vastly improves deep sleep power consumption and control of hbernate/sleep ...

couldn't remember if you were using picoW or zeroW