OpenEVSE hardware does not currently measure voltage. The voltage used in energy calculations is assumed to be 120v for L1 and 240 for L2. This value can be changed with a RAPI command or updated real-time with a external source via MQTT.

To change the value for voltage:

  • Login to OpenEVSE WiFi

  • Click the "System" Tab

  • Enable "Developer Mode"

  • Click on the "RAPI" Tab that is now visible

  • Determine the voltage in milivolts while vehicle is charging at the desired current.
  • Example 223576 - set voltage to 223.576
  • Enter the command $SV xxxxxx  and click "Send" to get the saved calibration value
  • NOTE - - volatile - value is lost, and replaced with default value VOLTS_FOR_Lx at boot