I want to track/register a heat pump running time based on current, ie. measure cycle from time when current goes over 0.2 A to the time when current goes below 0.2 A, summarize it, save the sum, gradually update and display the sum in format hh:mm.
Current is already measured by Sonoff POW.
One cycle might be one ore more within one day or even one in more days.
Any advice from more experienced than I am please?
Update:
Well, after some research I can use stopwatch to measure one cycle 
Still need to have the sum updated when a new cycle occures and have it saved.