Start a new topic

Adjust fixed voltage for power calculation

Hi there, I live in New Zealand and our nominal mains voltage is 230VAC -/+ 5% so the calculations are all a bit low. Is there any way to change the fixed value?

Hi Ethan,

There are a few ways. The value of your voltage can be input into the source code and compiled into firmware.

A workaround would be to calibrate the ammeter 5% low using WiFi in developer mode in the  RAPI tab. Amps would read a little low but power calculations would be closer.

The latest development firmware has an option to set voltage, but will be lost each reboot. I am planning to validate the firmware and create a release in the next couple weeks.

SV mv - Set Voltage for power calculations to mv millivolts

 $SV 223576 - set voltage to 223.576


  - only available if VOLTMETER not defined and KWH_RECORDING defined

  - volatile - value is lost, and replaced with VOLTS_FOR_Lx at boot

The last and most dynamic option uses a live voltage from another source (solar, energy meter, etc) over MQTT and updates the voltage every fer seconds using updated firmware and the command above. For this you need the latest ESP32 WiFi module and code 3.2.0 or later.


Thanks for the comprehensive response Chris! I figured out a way to extract my line voltage from my UPS and publish to a MQTT topic through Home Assistant every 10 minutes. Probably not very accurate but will do for now.

@Ethan Rose.. Realy old post, but jsut wondering where you bought your gear from.. I cant' get a response here

Hi there, I ordered from the OpenEVSE store page as far as I can tell from old emails.

1 person likes this

THanks Ethan.. I'm in NZ as well..  I just got a response.

No problem. I actually have the kit sitting unused (without antennae) so could potentially sell if you are interested. The antennae are generic so you could get these locally. Let me know how to get in touch if you like.
Login or Signup to post a comment