I have received design review comments on revision 1 from E-peas, the harvesting IC manufacturer. They said that the IC signal BUCK should not be accessible to the user because it's an internal voltage that should not be so dirty. In addition I had brought out the SELMPP0 and SELMMP1 signals to the connector that could be connected to BUCK signal.

I started a new design. I removed BUCK, SELMPP0 and SELMPP1 from the connector. SELMPP0 and SELMPP1 can not be changed externally anymore, they are set to a fixed vallue on board, if you want to change you need the cut a trace on the board and make a solder jumper. I wanted to make the design smaller and cheaper to produce and so I removed the battery voltage measurement divider, if people want it they can add it externally. The circuit already has an output to warn the user of an impeding 3.3V shutdown (STATUS pin) in case the battery runs low.  

I could shrink the board from 1.0x0.6inch to 0.8x0.6inch.

I have also added pin names to the silkscreen so the board is easier to use. I have ordered a new set of PCBs from Elecrow for prototyping before I make them assemble a batch of 50 that I want to sell on Tindie,