The ultra low power reconfigurable digital logic in YDrip makes it possible to log more than just water usage. The design is great for any application that needs to do simple logic like counting, leak detection or more. Smart meter reading is one of those applications. Most smart meters work by flashing an IR led to indicate electricity usage. You could use a general purpose CPU and wake-up on a GPIO interrupt, but this means the power hungry processor will wake up multiple times a minute draining battery. With YDrip, we can program the digital logic to count for us and wake the CPU when necessary. Using this approach we only use 60uA while reading.

I 3D printed an LED housing and clamp holder for testing. In hindsight, using two claps to hold the threaded rode would provide more stability for the LED.

Three wires provide power, ground and signal from the YDrip expansion connector to the LED.

Here is the github branch I made for the software modifications: 

https://github.com/YDrip/ydrip-esphome/tree/smart_meter