we use 2S Lithium-ion battery connecting to Vin pin. Below you can see the circuit diagram used in the RFID-based attendance system project. If you are completely new to using RFID, you can check out ...

The module measures 15 mm × 23 mm × 3 mm with a supply voltage of 1.8 V to 3.6 V. It operates between -40°C and +85°C, with a sleep mode current as low as ~5 μA when the ESP32 is asleep. The ...