Solar harvesting into Li-ion battery

I have received R2 PCBs and assembled one and guess what, it works.

I have ordered 50x PCB assemblies from Elecrow, it will take 3 week to ship. Now I need to prepare the Tindie page where I will be selling these. 

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,

I have soldered the components onto 3 boards using a solder paste stencil and a hot air gun. 

They also solder well on to 0.1" header pins for use in a breadboard. 

Then hardware verification could start. 

I connected a 20x25mm Li-Ion battery and 1V/100mA 30x25mm solar panel. I measured the 1.8V and 3.3V on the outputs. which only happens when the circuit is able to charge. The solar panel voltage was close to the expected 75% of the open circuit voltage. The battery voltage divider with 4.7M and 10M resistors worked as expected. As well as the mosfet with the status output pin. 

Today I have received revision 1 PCBs from Elecrow. They look good. I like the black color. I received 13 while I ordered 10.

In coming days I will solder and test a few. And if all is good I want Elecrow to produce a small batch that I can sell on Tindie.