ESP32: Tips to increase battery life (15 weeks and still going!) : r/esp32
Power ESP32/ESP8266 with Solar Panels and Battery | Random Nerd Tutorials
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batteries - How do I implement a simple and efficient voltage divider for battery level readings for a ESP32 board? - Electrical Engineering Stack Exchange
Monitoring Battery Voltage | Details | Hackaday.io
How to measure battery level with ESP32 microcontroller | Andrey Ovcharov