Enable / Disable dc relays for 1,2,3 phase connection

[Tinbum1]

To enable 2 other contractors to be added and to be controlled by the 2 DC relays for 1,2,3 phase charging using rapi $SR and $SS and energy calculation.

[chris1howell]

Assuming 3 Phase based on DC Relays Enabled/Disabled is not possible. Many users in split phase countries (US, Canada, Japan, Mexico, etc.) use either 2 x Singe Pole - Single Throw (SPST) Relays or 1 x Double Pole Single Throw (DPST).

I would reccomend this PR focus on adding the ability to Enabling and Disable each relay including the AC_Relay as well. The feature is good and could be usefull for many use cases. The juicebox replacement boards do not even have the AC relay driver installed.

[Tinbum1]

I'm not sure what you mean. The 'assuming 3 phase' is selected in the GUI.

[chris1howell]

  // Multiply calculation by 3 to get 3-phase energy.
  // Typically you'd multiply by sqrt(3), but because voltage is measured to
  // ground (230V) rather than between phases (400 V), 3 is the correct multiple.
  mws *= 3;
  if (relay1Enable && relay2Enable){mws *= 3;}
  else if (relay1Enable || relay2Enable){mws *= 2;}
  else {mws *= 1;}   

I am not a programmer but to me that looks like. If relay 1 AND 2 are enabled the multiplier is 3. If relay 1 OR 2 is enabled multiply by 2 and if none multiply my 1.

Note Split Phase (US, Canada, Japan, Mexico, etc.) does not need to multiply current by 2, that already happens on the voltage Single Phase is 120v and Split is 240. Multiplying both current and voltage would be correct for Europe but 2X for Split Phase countries.

[Tinbum1]

Yes, but that is only done if

#ifdef THREEPHASE
// Multiply calculation by 3 to get 3-phase energy.
// Typically you'd multiply by sqrt(3), but because voltage is measured to
// ground (230V) rather than between phases (400 V), 3 is the correct multiple.

  if (relay1Enable && relay2Enable){mws *= 3;}
  else if (relay1Enable || relay2Enable){mws *= 2;}
  else {mws *= 1;}      

#endif // THREEPHASE

which is selected in the GUI edit- no at compile. (GUI sets calculations in openevse_esp32_firmware)

[chris1howell]

I commited to the linco-work branch, we are about to push it out as 9.0.0.
8b84462

Add per-relay enable/disable control via RAPI ($SR/$GR commands)
Allows individual DC1, DC2, and AC relay outputs to be enabled or
disabled at runtime via new $SR and $GR RAPI commands. Settings are
persisted to EEPROM (offset 39) and applied on boot.

GR - get relay enable status
response: $OK dc1 dc2 ac
dc1/dc2/ac: 1=enabled 0=disabled
$GR

SR n 0|1 - enable/disable relay output (saved to EEPROM, applied at boot)
n: 1=DC relay 1, 2=DC relay 2, 3=AC relay
0=disable 1=enable (all relays enabled by default)
$SR 1 0 - disable DC relay 1
$SR 2 0 - disable DC relay 2
$SR 3 0 - disable AC relay
$SR 1 1 - re-enable DC relay 1

Firmware is built here:
https://github.com/OpenEVSE/open_evse/actions/runs/27229032632

[Tinbum1]

Thanks that looks nice.
New to all of this and still learning but think it will mean I have to alter ( simplify :) ) my pull request at OpenEVSE/openevse_esp32_firmware#1099

edit noticed you say "Settings are persisted to EEPROM (offset 39)" which I can understand. Just wondering how that will work when I was looking to change relay states during charging as PV power increases / decreases and would that degrade chip?