Comment by sho_hn

About 7 months in the first run. I recently switched things to a more efficient TPS63020-based voltage converter though, which has an extremely low operating quiescent current of only 25uA in low power mode (1/4 of the MT3608 I previously used). I'm hoping for more in the next!

The comparison will also be apples-to-oranges though since I also switched it to a 3500 mAh 18650 during that revision ... self-drain and therefore the battery make itself now become a big factor ... ask me in a few years how it went? :-)