Solar Super-Cap Energy Harvesting ESP32 E-Ink

That is a lot of buzzwords to throw together but the idea is to make some extremely low powered wireless devices for sensing and display. I have had the idea kicking around for a while to make a mailbox detector but I didn’t want to have a battery. I figure a super cap could store up solar power for some period of time and then the esp can come out of hibernation to check status and turn on the wifi long enough to send a quick message. Of course I was thinking of diodes and good intentions for the power side of things until I found out about energy harvesting chips and a board a guy in the Netherlands made. (links below).

The chip is designed to maximize output from the solar cells to charge a cap or battery and then provide a 3.3 and 1.8 volt outputs. there is even a status pin to give a fraction of a second warning of power failure.

Super caps are crazy cheap and large these days compared to where we were just a few years ago. About three dollars for 10 Farads on Aliexpress! I bought a few different sizes to play with.

The other use I have is for E Ink displays to be able to store up some room light, wake up to gulp some data, and then display it before hibernating again. I have some Lilygo TT5 two color displays I want to prototype with. They seem to be discontinued and I am not sure how difficult the older demo code will be.


Solar harvesting board

The solar harvesting chip

Datasheet for the chip

Super caps

Harvesting board, TT5 ESP32 E Ink and Flipper for scale

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