as in the previous lead-acid battery charger circuit. Additionally, this charger reduces VIN(REG) to 15V, tracking the reduction of the solar panel VMP at low currents. D6 and C6 implement a ...

This half-inch square ultra-low power energy harvesting LiPo cell charger ... battery health monitoring and undervoltage protection. [Kris] has been using the board along with a small 2.2 Volt ...