If you’d like to save household power, turning off the lights when you’re not in a room and only running appliances when needed is a good idea, but how much energy are you really saving? You could take a guess or do some rough calculations, but in order to measure power consumption hacker “deba168” has come up with a nicely finished based on the ESP8266-equipped Wemos D1 Mini Pro.
Due to the Wemos D1 Mini Pro’s ability to take in analog signals and communicate wirelessly, the project is fairly straightforward. A Hall effect current sensor produces an analog signal proportional to the current used by the appliance plugged into the device, and the Wemos takes this information and calculates the power used. This is passed on over Wi-Fi to the Blynk app and your Android or iOS phone. You can then monitor power usage and change parameters around as needed, such as the device’s calibration, power factor, and how much power actually costs at your location.
To give it a finished look, deba168 designed a nice 3D-printed enclosure available here. The write-up outlines instructions for 230VAC, but the same concept could certainly be adapted to different locations (such as the US).