search

3KUdelta / Solar_WiFi_Weather_Station

Based on the work of Open Green Energy: First solar Zambretti Forecaster
111 stars 49 forks source link

Battery Voltage Monitoring #21

Closed polanskiman closed 4 years ago

polanskiman commented 4 years ago

Hello,

I had a question about the voltage monitoring. Code says:

//******Battery Voltage Monitoring*********************************************

 // Voltage divider R1 = 220k+100k+220k =540k and R2=100k
  float calib_factor = 5.28; // change this value to calibrate the battery voltage
  unsigned long raw = analogRead(A0);
  volt = raw * calib_factor/1024;

Question is, how one calibrates the battery voltage?

Thank you.

3KUdelta commented 4 years ago

Hi,

First measure the voltage on your battery. No run the program and you will get the voltage on the serial monitor. If these two values are different then change the factor (float calib_factor = 5.28;) accordingly.

polanskiman commented 4 years ago

Hi. Thank you. Not sure exactly how to find the value of the float calib_factor. I'm either getting tired or my brain is not functioning properly.

Voltmeter says 3.983v Serial monitor say 4.847v (yes I added an additional decimal in the code - lol)

3KUdelta commented 4 years ago

OK, quick maths: Formula in the code: volts = raw calib / 1024 1.) Find raw first: 4.847 = raw 5.28 / 1024 --> raw = 940 2.) Find calib: 3.983 = 940 * new_calib / 1024 --> your calib_factor: 4.338

Should work...

polanskiman commented 4 years ago

I am tired indeed!

Thank you.