Dfrobot Gravity I2c 3.7v 5v Programmable Low Power Li Battery Fuel Gauge Module Maxim's Algorith For Solar Street Light Robotics - Demo Board - AliExpress
Adafruit LC709203F LiPoly / LiIon Fuel Gauge and Battery Monitor [STEMMA JST PH & QT / Qwiic] : ID 4712 : $6.95 : Adafruit Industries, Unique & fun DIY electronics and kits