The current measurement in OpenEVSE can be calibrated to more closely match another accurate or trusted source.

OpenEVSE RAPI commands are used to get and modify the calibration value.

To calibrate begin a charge at the desired current.

  • Login to OpenEVSE WiFi
  • Click the "System" Tab
  • Enable "Developer Mode"
  • Click on the "RAPI" Tab that is now visible

  • Enter the command $GA  and click "Send" to get the saved calibration value
  • OpenEVSE should respond $OK 220 0 (default) values for Scale and Offset

  • leave Offset at 0
  • change the value for Scale by + or - 5 until close then + and - 1 to fine tune
  • Enter new value for Scale $SA xxx 0 and click "Send"
    OpenEVSE should respond >$OK^20
  • Compare OpenEVSE displayed Current with the calibration source and continue to adjust as required