I have a problem, I want to make a voltage sensor that will be seen through the esp32 microcontroller, and the voltage is 175 - 224 V DC from battery 70 cell. What circuit should I make? If I use a voltage divider, how many resistors should I use? and I also want to monitor the current which is approximately 17 A to 20 A using what is the most appropriate circuit? Thank you

 

Hi mhilmi,
Welcome to AAC.
As you may know, the ESP32 ADC will only accept 0V through a +3.3V input voltage.
As you have a ~50V signal variation, based on a 174V voltage, you will require to cancel out the 174V and reduce the 50V signal to 3.3V.
Have you already drawn up a draft circuit method?
E
BTW: I would suggest you check the linearity of the ESP32 ADC section, it has problems

@mhilmi_w
https://forum.arduino.cc/t/fixing-the-non-linear-adc-of-an-esp32/699190

 

Hi mhilmi,
Welcome to AAC.
As you may know, the ESP32 ADC will only accept 0V through a +3.3V input voltage.
As you have a ~50V signal variation, based on a 174V voltage, you will require to cancel out the 174V and reduce the 50V signal to 3.3V.
Have you already drawn up a draft circuit method?
E
BTW: I would suggest you check the linearity of the ESP32 ADC section, it has problems

I originally wanted to monitor the battery voltage using ESP 32 and it uses a voltage divider circuit, but I haven't found the most appropriate circuit because my previous experiment experienced a short when I installed the voltage divider. Is there a good circuit for this?

 

Show your divider circuit with specs.

 

Hi mhilmi_w,

you can refer to this sample :

https://f1atb.fr/power-measurement-with-an-esp32/

 

hi mih,
This basic circuit is one option.
E

 

just note that with those values would require R1 to be at least 2W. or you can increase R1/R2 values tenfold...
also it would not hurt to add some sort of clamping of the input (just in case).

 

and I also want to monitor the current which is approximately 17 A to 20 A using what is the most appropriate circuit? Thank you

One of These modules should work.

 

hi mih,

If you do not have a +5V supply available, you could use a MCP6001 powered by 3.3V and perhaps limit the output range to 0V through +3V.
As stated, ensure that the divider resistor are correctly power rated or increased in value or use the values in this image.
I would suggest that a 5k Trim pot for the lower resistor, this will enable adjust of the OPA Vout Span.

E

 

I would suggest that a 5k Trim pot for the lower resistor, this will enable adjust of the OPA Vout Span.

And I would suggest a 4.7K resistor in series with a 1K pot to make the adjustment less sensitive.

 

Morning Bob,
I take your point, but a 4k7 would take the settings off-scale, perhaps a 2k fixed and a 1k trim would give an easier set up.

E

 

hi mih,

If you do not have a +5V supply available, you could use a MCP6001 powered by 3.3V and perhaps limit the output range to 0V through +3V.
As stated, ensure that the divider resistor are correctly power rated or increased in value or use the values in this image.
I would suggest that a 5k Trim pot for the lower resistor, this will enable adjust of the OPA Vout Span.

E
View attachment 339935

Thank you very much for your help, after this I will try. Actually I have tried several things using a larger resistor, but maybe the wattage is less so the circuit is shorted which causes the mcb to work for protection. maybe if there are more problems later I will let you know. thank you