@robert-hh The hearbeat LED flashes when the board and code are working properly. If I notice that the data is not updating, I'll go look at the board and the heartbeat LED won't be flashing. I'll hit the reset button on the board and everything will work normally again. I think I'll setup an identical rig but power the USB power port from a variable DC supply. Then I can turn the voltage down and see what happens.

@robert-hh - Thanks - I'll get a couple and take a look. Since I only do this stuff for my own use, my volume scale is usually 1!

@JimT Sorry, I could have told you. You may use a 1N4001 model (or any of the 1N400x series). You have to put that in series to the solar module, Anode of the diode at the + pin of the solar module, Kathode (the side with the ring on the diode case) to the charger module's + input. Doing that, the voltage of the solar panel will be reduced by about 0.7 V. I would add a small load too behind the diode, to cap the no-load case, like by a 1 k resistor at the chargers module input between + and GND. You can use the additional power in lead pads of the charger module for that. I see that the module has already a built in diode, but that is a MPB120 Schottky type and reduces the Voltage only by 0.3 V.

@VladimirAkopyan there are a couple of expansion boards already which I think are enough for prototyping and even smaller units PySense PyTrack Given the pricing and the fact that the grove connectors while nice to have are not essential whats the value add? You can also use grove with pycom base boards you just need the grove to pin adapter The only thing left is a solar trickle charger but these shouldnt be too hard to get I think i know where you are coming from but just dont think there is an urgent need - maybe there is Andrei

Why would you want to run your device directly from a solar cell? You will need a much larger panel/ device and it will be extremely weather dependant. Stop torturing yourself and get a tiny solar charger and a lipo battery, and [image: IMG_0245-450x300.jpg] Plug this into the battery port of the board, and you are done!