The ESP32 draws quite a lot of current when running BLE (without Wifi), unless that's been fixed recently. IIRC, the TTGO boards have poor low-power design that

The ESP32 draws quite a lot of current when running BLE (without Wifi), unless that's been fixed recently. IIRC, the TTGO boards have poor low-power design that will kill the 18650 battery in a few days, no matter what you do, that could perhaps be fixed with a small modification though. I have a hardware design that might be an interesting starting point. It's based around nrf52 (Cortex M4F with BLE and nice SDK), 400mah battery, microphone, speaker, 3*4 RGB LED matrix, gyro/accelerometer, NFC. Very small device, 35mm across. Can extend the top of the PCB, add a small OLED screen and a LORA radio. Hitting $30 price point shouldn't be a problem. Email in profile :-) https://photos.app.goo.gl/qUyrRYDrtu2SHsHR9 https://photos.app.goo.gl/qUyrRYDrtu2SHsHR9