Actual power consumption measurements
The power beast – ESP8266
One of the very first and most important measurements is how much the ESP consumes when its waken up. I used my voltage/current logger to measure this. This is the result:
It shows that the ESP is awake for about 0.7 seconds and on average it uses 78mA. The raw data can be downloaded here.
AtTiny85 and the sensors
Next is measuring the cycle of the AtTiny when it does it’s measurements. The chip uses so little power that I had to change shunt resistor of my INA219 from 0.1R to 10R, giving it 100 times more sensitivity.
It shows that a measurement takes about 180 ms and uses about 1.35 mA on average. The raw data can be downloaded here. I have deliberately reduced the clock frequency on the AtTiny from 8 MHz to 1 MHz. This makes it go from 10+ mA down to about 1 mA.
My modification to my datalogger:
Sleeping power consumption
With a multi-meter I was able to measure 23.5uA for the entire device when both the AtTiny and the ESP are sleeping. This is without any power regulator or DC-DC converter. I still havn’t decided which way I will go here. But it should be possible to find a solution under 10uA quiescent current.
With the above measurements I can now do the real world calculation of the battery consumption. And it was quite close to my first calculation.
This should be fine for running some years on AA batteries 🙂
I will add more info about power regulators / DC-DC converters when they arrive from china. This can take 1-2 month. I hope you enjoyed reading about my little project.
Comments are welcome 🙂