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Use of EVSE Controller with latching relay

Is there any possibility to use Universal EVSE Controller and adopt the firmware in order to switch double coil latching relay (for example

The latching relay  has 3 coil contacts to switch realy 1,2 and 5:

to close the relay - 1(+), 2(-) OR 1(-),5(+) 

to open the relay - 1(-),2(+) OR 5(+),2(-)

OpenEVSE has 2 relay outputs that switch a path to ground and a common +12v

It looks like you could wire:

OpenEVSE    Relay

+12v common  5(+)

Relay 1 1(-) close

Relay 2 2(-) open

However there may be an issue with current, OpenEVSE has 2.5 watts avalaible on 12V each relay requires 3 watts for at least 50ms. Since you would need 2 relays that would be 6watts.

You would also have to modify the firmware to switch on and reset the relay. 

Thank you for quick reply. My friend bought 3 phase 11kw EV charger for China and unfortunately it was faulty and he got new one. The faulty one was given to me and I found out the problem is in the controller of Chineese EV charger (with HFE latching relays) which it is not reparable. I thought that maybe I can use the OpenEVSE controller.

I connected the latching relay with the EVSE controller v5.5. using DC relay contacts and EV simulator and switched charging on. The charger started charging normally except the problem was the buzzing noise which came from the latching relay because the 12v is present constantly. When I switched off the charger, I got the error message "Stuck Relay" probably because the firmware should be changed. I manually switched the latching relay and restated the EVSE controller and I was able to start charging again. 

I opened the open_evse firmware in the Aurdino and found that probably the code in J1772EVSEController.cpp should be changed in:

void J1772EVSEController::chargingOn()

void J1772EVSEController::chargingOff()

Here I would appreciate your help because I not very good in programming (I have only small experience in Perl programming). What should I change in order to:

1. to give 12v from both DC relay of EVSE controller just for 1 or 2 seconds

2. to have functionality of DC relay 2 to open and on DC Relay 1 to close the latching relay.


I have a similar problem with a chinese charger. Would love to see a solution that would allow replacing the controller with OpenEVSE. 

I managed to integrate OPENEVSE controller v5.5 and WIFI modul in 3 phase 11kw EV charger (with latching relays) from Aliexpress. On the photos you will see the result. Instead of current transformer CFCI I used the RCM14-03 unit from Stegen Electronics (detect AC and also DC residual currents) followed the instruction on the openenergy monitor forum

I also adopted the open_evse firmware in J1772EVSEController.cpp in order to switch latching 12v relays and changes has been made in (red coloured):

void J1772EVSEController::chargingOn()


  // turn on charging current

#ifdef OEV6

  if (isV6()) {

#ifdef RELAY_PWM

    Serial.print("\nrelayCloseMs: ");Serial.println(m_relayCloseMs);

    Serial.print("relayHoldPwm: ");Serial.println(m_relayHoldPwm);

    // turn on charging pin to close relay




    // switch to PWM to hold closed




#else // !RELAY_PWM


void J1772EVSEController::chargingOff()


 // turn off charging current

#ifdef OEV6

  if (isV6()) {














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