Power share in smartmode doesn't charge (well) when there's only current for a few chargers and starts "oscillating"

[timcooijmans]

Describe the bug
I have a setup with 2 (and planning to expand) SmartEVSE's running v3.10.0 in power share master/slave setup in smart mode to limit the mains current. The setup is a bit strange: mains=25A, circuit=63A, both chargers are min=6A, max=32A because I have enough solar to charge with 63A (in optimal conditions). However now in the winter there's not much solar so I commonly have 10-14A available for the both SmartEVSEs.

Let's assume 14A is available and both cars are starting to charge. The cars will both get 7A of power assigned and charging starts. Now available current drops to 11A (so 3A of overcurrent). I would expect only 1 of the SmartEVSEs to stop charging (and the other to get the full 11A). However what happens is that both SmartEVSEs stop charging. Next both EVSEs start again and the same happens again. The result is that all the EVSEs are all starting/stopping every few minutes.

I expect that this issue only gets worse when I gets bigger to 6 SmartEVSEs as it seems that 36A needs to be available to allow any car to continue charging.

Upload your config

config

{
  "version": "v3.10.0",
  "serialnr": 8524,
  "mode": "SMART",
  "mode_id": 3,
  "car_connected": true,
  "wifi": {
    "status": "WL_CONNECTED",
    "ssid": "3668a2",
    "rssi": -33,
    "bssid": "82:8A:20:71:ED:CE"
  },
  "evse": {
    "temp": 20,
    "temp_max": 65,
    "connected": true,
    "access": 1,
    "mode": 1,
    "loadbl": 1,
    "pwm": 175,
    "custombutton": false,
    "solar_stop_timer": 0,
    "state": "Charging",
    "state_id": 2,
    "error": "None",
    "error_id": 0,
    "rfidreader": "Disabled",
    "nrofphases": 3,
    "rfid": "Not Installed"
  },
  "settings": {
    "charge_current": 103,
    "override_current": 0,
    "current_min": 6,
    "current_max": 32,
    "current_main": 25,
    "current_max_circuit": 63,
    "current_max_sum_mains": 0,
    "max_sum_mains_time": 0,
    "solar_max_import": 0,
    "solar_start_current": 4,
    "solar_stop_time": 10,
    "enable_C2": "Always On",
    "mains_meter": "API",
    "starttime": 0,
    "stoptime": 0,
    "repeat": 0,
    "lcdlock": 0,
    "lock": 0,
    "cablelock": 0
  },
  "mqtt": {
    "host": "10.40.0.20",
    "port": 1883,
    "topic_prefix": "SmartEVSE/8524",
    "username": "smartevse8524",
    "password_set": false,
    "tls": false,
    "status": "Connected",
    "smartevse_server": false
  },
  "ocpp": {
    "mode": "Disabled",
    "backend_url": "",
    "cb_id": "",
    "auth_key": "",
    "auto_auth": "Disabled",
    "auto_auth_idtag": "",
    "status": "Disconnected"
  },
  "home_battery": {
    "current": 0,
    "last_update": 0
  },
  "ev_meter": {
    "description": "Disabled",
    "address": 12,
    "import_active_power": 0,
    "total_wh": 0,
    "charged_wh": 0,
    "currents": {
      "TOTAL": 0,
      "L1": 0,
      "L2": 0,
      "L3": 0
    },
    "import_active_energy": 0,
    "export_active_energy": 0
  },
  "mains_meter": {
    "import_active_energy": 0,
    "export_active_energy": 0
  },
  "phase_currents": {
    "TOTAL": 714,
    "L1": 236,
    "L2": 249,
    "L3": 229,
    "last_data_update": 1768339236,
    "original_data": {
      "TOTAL": 714,
      "L1": 236,
      "L2": 249,
      "L3": 229
    }
  },
  "backlight": {
    "timer": 119,
    "status": "ON"
  },
  "color": {
    "off": {
      "R": 0,
      "G": 0,
      "B": 0
    },
    "normal": {
      "R": 0,
      "G": 255,
      "B": 0
    },
    "smart": {
      "R": 0,
      "G": 255,
      "B": 0
    },
    "solar": {
      "R": 255,
      "G": 170,
      "B": 0
    },
    "custom": {
      "R": 0,
      "G": 0,
      "B": 255
    }
  }
}

Upload a debug log
Not yet created

To Reproduce
Steps to reproduce the behavior:

1. Make x * MIN amps on MAINS available for x SmartEVSE in smart mode with power share
2. Make x * MIN -1 amps on MAINS available

Expected behavior
Only 1 SmartEVSE stops charging to avoid overcurrent on MAINS

[dingo35]

This is known behaviour; in the "calcbalancedcurrent" branches the scheduling algorithm is redesigned to switch off single devices, but because (up until now) no users complained (no real life use case) AND it is a big change that probably will introduce some new bugs, I never merged that code...

[mstegen]

Yes this has been the behaviour since SmartEVSE v2.
I've had several questions about this over the years. Problem is if we for example switch off a Node first, people ask why the Node stops first, instead of the first or last EVSE that started charging.
There could be multiple preferred ways to handle this.

[dingo35]

Its been some time ago, but I built several user configurarion options; I think I had "last one first", "first one last", "nodenr" (so Master is switched off last).

Those config options + the logic around it turned out to be the easy part; its the algorythm that distributes the available power over the different nodes that is the big change.

I think I still have an updated version calcbasecurrent7 in one of my backups, Ill try to sync it to the cloud repo ...

[timcooijmans]

Thank you for your replies.

I guess there are so many options that's it's impossible to support everything (which charger to stop, how to distribute power and so on). One or two well-defined configurable options would already be a huge improvement.

If you have a version that I can test, I'm happy to test!

[mtreven]

Hi in my case I am using for half a year 2 chargers in master slave configuration. On the chargers there is 3.8.5 version of the code. I would expect when there is enough available current that chargers will split the current if it is available more then 12A per phase (min current is set to 6A per charger). What happens is that master start charging with max available power and the slave waits (waiting for power) until master finished with the charging. I would expect to split the power but they are just charging one after another. In half a year it twice happened that master didn’t want to start charge during the night. After reboot everything started to work again.

I didn’t update the code when I build the charger so the explained behaviour is from the version: 3.8.5 When I will find some time I can try with latest one to se if I get simmilar as timcooijmans.

If you are planning to do any improvements in master/slave configuration I am happy to test in my setup.

Current setup of the circuit:
"settings": {
"charge_current": 60,
"override_current": 0,
"current_min": 6,
"current_max": 10,
"current_main": 45,
"current_max_circuit": 32,
"current_max_sum_mains": 48,
"max_sum_mains_time": 2,
"solar_max_import": 0,
"solar_start_current": 4,
"solar_stop_time": 10,
"enable_C2": "Always On",
"mains_meter": "Sensorbox",

"mode": "SMART",
"mode_id": 3,
"car_connected": true,

[Lordhu]

Thank you for your replies.

I guess there are so many options that's it's impossible to support everything (which charger to stop, how to distribute power and so on). One or two well-defined configurable options would already be a huge improvement.

If you have a version that I can test, I'm happy to test!

I would also be very happy to test this! I notice exactly the same behavior as the topic starter: When charging 2 cars at the same time, the charging starts and stops very often.

[Lordhu]

Been thinking about this a little more: Maybe a "partial" solution can less complex but still usefull:

It might help introduce a setting to limit the number of smartevse's that can charge simultaneous (in Smart mode).

I rather have that the cars charge one after the other, than the current solution where they start stop a lot. This might also help to prevent a situation where charging will never start if you have multiple smartesve's on a relatively small power supply (as timcooijmans writes in the first post)

If this setting is activated, the logic Dingo35 describes can maybe be used to select what will happen: "last one first", "first one last", "nodenr" (maybe the ability to give a priority 1-10 to a nodenr?)

[basmeerman]

I've done some testing with claude and implementing this scenario. Currently in the proces of testing it on my smart evse.
Choices made in scheduling: https://github.com/basmeerman/SmartEVSE-3.5/blob/master/docs/priority-scheduling.md