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INA219 battery voltage reading error

Discussion in 'Sensors and Actuators' started by zazas321, Dec 2, 2018.

  1. zazas321

    zazas321

    6
    0
    Oct 1, 2018
    Hello guys. Have anyone got some experience with INA219 voltage and current sensor?I have bought an adafruit prebuilt module and I am getting a voltage error and I am not sure where it is coming from! I have a circuit ( see picture) and I am trying to measure my supply voltage and current. I was using 10V supply but on serial monitor and display I only get about 9.4-9.5V reading. According to the datasheet, INA219 measures the voltage across Vin- to GND. I have measured that voltage with multi meter and I got 9.9 ( which is close enough for me to 10). So if it measures Vin- as it states why the serial monitor reading and LCD display only displays 9.5?

    I have also tried using 5V supply and simplified version of the circuit and the reading i get is 4.9 with 40mA current load, as the load current increases, the error increases as well

    I have recently bough a 9V alkaline battery to do some testing again and I got the same results:
    Battery voltage when no load connected 8.8V
    Battery voltage when load is connected 8V
    measured voltage across Vin- and GND = 7.95V
    Displayed value - 7.5V
     

    Attached Files:

  2. kellys_eye

    kellys_eye

    4,289
    1,143
    Jun 25, 2010
    There is a calibration register in the device. Have you checked out the datasheet to see what facilities there are for calibration?
     
  3. zazas321

    zazas321

    6
    0
    Oct 1, 2018
    Do you mean PGA or something else?
     
  4. kellys_eye

    kellys_eye

    4,289
    1,143
    Jun 25, 2010
    PGA?? Did you read the datasheet?

    Another possibility is that there is a dry solder joint somewhere adding additional resistance where it isn't needed.
     
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