When we think about sensor terminal working outside, battery replacement is a headache problem if we put it on the mountain top or roof top. Here I made a "self-powered board" contains RTL8710 module, BME280 I2C sensor, OLED display and LiPo charging circuit powered by Solar cell!!

So we don't need to care power source anymore and just put on somewhere as we wish and continue to work till LiPo's lifetime!!

Power consumption (current flow) of this board is,,,

OLED activation, not web server accessed: 30mA

OLED activated, web server accessed: 70mA ! (very short time, like spike)

OLED turns-off, not web server accessed: 17mA (continuous)

OED turns-off, web-accessed: 60mA (during access, very short time, spike current)

So for the 24/7 operation, considering night time length, just 300 mAh battery is well enough if not so frequent access (for example, just one time every hours). Indeed RTL8710 has a deep-sleep function and if we utilise it, we may be able to work with just 100mAh battery...

Actual operation can be found in the following movie. Have fun!