Why did I stop the logging after almost 12 days? The batteries got too low - down to 0.9V/cell. That's a good place to stop discharging #NiMH AAs.

I spent nearly zero effort thinking about power efficiency, but getting about 2 weeks on a set of AAs isn't bad.

It uses a #LM317 to get a steady 3.3V, but there are better ways (with smaller dropout and lower energy waste) that I should look into. I measured 4.5mA current on the LM317's output, which I bet I could reduce. #electronics