Hello,
In the process to find better isolated current measurement solution I am exploring the posibility to use the ACS712 Current Sensor Board with the ESP8266. As they are all over the place, so why not.
Main identified problems to solve:
ASC712:
5 Vdc power supply device
measure positive and negative 5/20/30Amps, corresponding to the analog output 100mV/A BUT
"ZERO" point, means no test current through the output voltage is VCC / 2 =5v/2=2.5V !
ESP8266:
3V only device
ADC range max: 0-1V
So far, the solution that I found was to use a difference amplifier:
If you know any other way to do it or have any related ideas, please feel free to share 
For reference: ASC712 Current module meets ESP8266
Part 2 of the story : programming the ACS712 Current reading function.
Question for any of you using frequently the ASC712 sensor: it is all the time so noisy or is just mine ?
Using the Voltage Level Shifter and DC op amp module with a big number of reading gives decent result but in case of direct voltage divier the noise level is very high.
I've used the ACS712 for a battery cycle testing station I was building. There was some noise but if you take multiple readings (I did 20) then average that, I was able to get good and consistent current values. I used an arduino though so that was pretty simple and straightforward.
xane514:
I've used the ACS712 for a battery cycle testing station I was building. There was some noise but if you take multiple readings (I did 20) then average that, I was able to get good and consistent current values. I used an arduino though so that was pretty simple and straightforward.
In my case, reducing the bandwidth (Cf around 10nF has done the job) and averaging values (32 readings) looks like the right recipe in a noisy environment.