My latest ESP8266 battery experiment platform. Here’s an ESP-07 connected to a single 18650 cell through a combination usb charging + protection board, as well as a 1N4001 diode. The idea with the diode was to use the 0.5v drop (at this low current) to protect the ESP from the 4.2v charging voltage.
The ESP-07 has an always on power led which I didn’t de-solder. I’ll get rid of it next time around. Oh, someone suggested earlier that I power the DS18B20 off a digital pin, so I’m trying that. GPIO5 powers the probe and GPIO4 reads it.
The cell I’m using is a counterfeit sourced from ebay. The seller proudly claims 5000mAh from one cell, ya, right. It weighs a fraction of what my genuine Panasonic cells weigh, and feels like it’s hollow. I guess that could be plastic case versus metal case, dunno.