Creasol DomBusEVSE is a fully tested DIN rail module, designed for Domoticz home automation system, to charge electric vehicles using the standard IEC 62196-2 Mode3 (AC charge, up to 22kW power).

It works as stand-alone (without any domotic controller) or in managed mode  (charging current controlled by Domoticz).

In stand-alone mode it works only as single-phase charger, because it's able to read only DDS238-2 ZN/S energy meter (single phase); using Domoticz home automation, it's able to manage three-phase charging by getting the current grid power value from Domoticz (e.g. SDM630 or other power meter already installed in Domoticz). The power value from the electricity grid is needed by DomBusEVSE to regulate the charging current preventing overloads/disconnections, and also to keep the max power set by the user: more info below.

Features

• Manages up to 4 class-1 (very accurate) Modbus energy meters DDS238-2 ZN/S (single phase), one to measure the charging power/energy, one to measure the power/energy exchanged with the electricity grid. Can also be connected to other 2 energy meters to monitor other loads/circuits, if needed (heat pump, kitchen, ...). As energy meters are really accurate, it's possible to get accurate statistics and charts about energy used to charge the electric vehicle and energy exchanged with the grid.
• Controls an external 2P contactor to enable or exclude mains power supply to the electric car, and fully check that contactor works as expected.
• 5 working modes, that can be configured by the Domoticz UI or by 2 UP/DOWN buttons:
  OFF: EV charging disabled (led status: red)
  SOLAR: use only energy from the solar system, assuring that power from grid is 0 (led status: green)
  25%: use both solar and grid energy, max 25% of the power availability (for example, with 6kW contract, use max 1500W from grid, + available power from solar) (led status: yellow)
  50%: use both solar and grid energy, max 50% of the power availability (for example, with 6kW contract, use max 3kW from grid) (led status: yellow)
  75%: use both solar and grid energy, max 75% of the power availability (for example, with 6kW contract, use max 4500W from grid) (led status: yellow)
  100%: use both solar and grid energy, max full power (for example, with 6kW contract, use max 6kW) (led status: yellow)
  MANAGED: charging current set by the domotic controller (by a script, for example) (led status: blue)
• AUTOSTART function: long press on DOWN button (1 second) to stop charging, or the vehicle disconnection set Mode to OFF. When the vehicle is plugged again, the charging mode is automatically restored to the previous charging mode. For example, if charging mode was SOLAR, every time the vehicle is connected the charging mode is set to SOLAR automatically.
  AUTOSTART can be disabled so when vehicle is plugged the charging process will not start automatically, but will start manually (UP button to change Mode, or by the Web User Interface) or will start based on time (a simple rule on the domotic controller to start and stop charging in the night, for example).
• It displays nice charts with
  - charging power/energy, that is differentiate into the two following charts
  - charging power/energy from solar (photovoltaic or other renewable source)
  - charging power/energy from the electricity grid
  - charging voltage and power factor
  - total power/energy from grid
  - grid voltage, power factor and frequency
• RGB led display current EV state:
  EV disconnected: 1 flash green
  EV connected: 2 flashes green
  EV charging: blue led flashes 1 or more times, indicating the current power (1 flash => less than 1kW, 2 flashes => less than 2kW, ...)
  EV error: 1 or more red flashes
  When a new EV mode is selected (from smartphone or using the UP/DOWN button), RGB led shows current mode for 1 second.

How does an EVSE work?

Although this is a fully tested product, it may be used by technical engineers only for development or demostration. Creasol declines all responsibility for damage to things or people.
Mains power supply (230V single-phase, 400V three-phase) is connected to the vehicle through a 2P or 4P contactor (relays) to assure that no power is applied when charging session is OFF.
Only the Control Pilot wire + earth/ground are connected to the EVSE module: control pilot is protected by transient voltage suppression device.
A smart EVSE module:

1. monitors the mains power supply through a energy/power meter
2. monitors the charging power supply, through another energy/power meter
3. monitors the control pilot to check the vehicle status (disconnected, connected, charging requested, ventilation requested, alarm)
4. send to the car a 1KHz PWM signal to specify the max available current for charging
5. activates the mains power supply through a contactor
6. records all measures to provide nice charts that permit to have a statistic about electric car consumption

With Domoticz, it's also possible to connect the vehicle cloud to get other informations about battery state of charge, odometer, location, speed, ...

How to make a DIY Smart Wallbox (EV charging station) using Creasol DomBusEVSE?

The following diagram shows the connection of the EVSE module to energy meter, contactor, RCD to get a complete smart wallbox, single-phase 230V, sensing the grid power to get the best charging speed preventing overloads and disconnections. Block diagram is available also in PDF format.

It's possible to make a three phase charger by replacing the contactor with a 4P version and using an three-phase energy meter connected to Domoticz so the current power drained from the electricity grid is fed by Domoticz to the DomBusEVSE module.

This device was designed for technical engineers only, for developing purpose. Creasol declines any responsibility for damage to things or people.

Bill of Material

• EVSE module Creasol DomBusEVSE
  
• Type-B RCCB that is able to detect differential currents protecting the circuit even if currents are in DC.
• One energy meter DDS238-2 ZN/S (Modbus version) to keep account of energy fed to the vehicle, charging power, ... This is a class-1 energy meter so very accurate. This energy meter is not essential: it is possible to omit it saving space and cost, but you would lose the statistics and charts on power and energy used for recharging the vehicle.
• One 2P 40A contactor (4P contactor in case of three-phase charger) to enable / remove mains power supply to the vehicle, disconnecting the vehicle if charging process is OFF.
• One energy meter DDS238-2 ZN/S connected to the electricity grid, to detect the import/export power and keep account of energy, voltage, power factor and frequency. This is also good to measure the power and energy consumed by the building, and have nice graphs showing these parameters over the years.
  In case that a power meter already exists, providing power value with max 10s interval, it's possible to use it without connecting the meter to DomBusEVSE, but adding a simple script that set a virtual device Grid Power on DomBusEVSE when power changes; the power value should be negative in case that power is exported to the grid.
• Type-2 or Type-1 cable to connect the vehicle, and of course some wires to connect all parts together. EV cable for single-phase recharge has 4 wires: Line, Neutral, PE and Control Pilot.
• If 13.6Vdc power supply is missing, a power supply unit 13.6V 15W is needed
• If a DomBus network was not installed, a USB/RS485 adapter is needed to interface the domotic controller
• If no domotic controller was installed, a single board computer like Rock PI-S (for a basic domotic controller with few automations), Raspberry PI4 or similar (more powerful, useful to have a full domotic system with several automations and hundreds of devices) is needed, as like as a 12V to 5V DC/DC converter to supply the single board computer.

Configuration

Make all wirings as indicated in the diagram above (click to get the PDF schematic with higher resolution), but connect only the energy meter that measures energy to the electric vehicle.

We suggest to put the wallbox modules in a indoor switchbox, possibly near the point where you'll park your car, but also near the main switchbox or solar inverter, if exists, to minimize cable length: use 6mm² (or 10mm²) wires for the mains power supply. Then place a small 10x10cm box where the electric car is parked, indoor or outdoor, connected by 3x 6mm² (or 10mm²) wires (L,N,PE) plus a shielded 2x0.22mm² cable (standard cable for alarm systems): one wire is connected to the CP terminal block (control pilot), and other wire + shield are connected to PE/GND. The Type-2 or Type-1 cable (with only plug connector to the vehicle) will be connected to the small box.

In case that device is used as stand-alone, without attached domotic controller, energy meters must be already configured with Modbus address=2 (to EV) and address=3 (to Grid): they can be purchased from Creasol Store asking to get address already programmed. Also it's possible to ask that EVSE module is preprogrammed with the right value of MAXPOWER (max power from grid), MAXCURRENT (max current supported by the EV cable).

The next instructions are relative to Domoticz controller, a free open-source home automation controller that let a full control of the wallbox and is highly recommended: it works in cheap hardware like Rock PI-S or Raspberry PI4, as like Linux computers, windows and Mac.

It's recommended to install Domoticz Beta, which is up-to-date, Python Plugin Manager (not available in Windows), then it's possible to install the Creasol DomBus plugin from Python Plugin Manager: in this way it's possible to get notifications about future updates of the DomBus plugin, and auto upgrade.

DomBusEVSE can be connected to the domotic controller / PC by a USB/RS485 adapter: a device will be automatically added to Domoticz -> Switches panel, with factory-default address ffe3.1: click on Edit button and add to the Description ,HWADDR=0x0001 or other unique address, then click Save button: click on Dashboard and then on Switches again to see, in the bottom, the EVSE devices: EVSE On, RL2, EVSE Supply, EVSE Mode, EVSE State, EVSE Current.  Click on EVSE Mode, and edit the MAXPOWER and MAXCURRENT parameters, then save.

Create a new room to group all EVSE device: Setup -> More Options -> Plans -> Room Plan, add a new room Wallbox or something else, and add all devices with address corresponding with the HWADDR set before. Then, click on Dashboard and select the Wallbox room.

As energy meters are factory programmed with Modbus address 1, first connect the energy meter between Type-B RCCB and contactor, and assign address = 2 in this way: select Domoticz -> Utility -> M1 Addr device, click on Edit button and write in the Description field ,ADDR=2 then save.  Then connect the main energy meter (that measure the power exchanged with the grid) and assign address=2: select Domoticz -> Utility -> M1 Addr device, click on Edit button and write in the Description field ,ADDR=3 then save.

If a energy meter connected to the electricity grid is already available, it's sufficient to install a simple script that, when the power from grid changes, update the value of the "virtual device" Grid Power that is automatically created

Finally, DomBusEVSE has additional support for:
* SPST relay output RL2, with 250V 5A capability, that can be used for any purpose

* up to 4 energy meters, so 2 additionally energy meters (with address=4 and 5) can be connected to get power statistics for the heat pump, kitchen, ....

All parts should be available in the Creasol Store, but not the Type-2 or Type-1 cable.

Domoticz and DomBusEVSE

The following picture shows the integration in Domoticz of the EV (Kia Niro car, using the plugin available with Python Plugin Manager) and DomBusEVSE module; it shows a trip to Garda Lake, Northern of Italy, with a short charging session at a 11kW station, and then a long charging session using DomBusEVSE wallbox in SOLAR mode (only energy from photovoltic).

During the charging session at home, in SOLAR mode, both the washer machine and the oven were switched on: in this cases the EVSE module reduced the charging current to the minimum and after 90 seconds ended the session until available power returned above the STARTPOWER parameter. As displayed in the charts below, the module assure that no power comes from the grid, in SOLAR mode.

DomBusEVSE wallbox in Managed Mode

When DomBusEVSE module is configured in managed mode, Domoticz is responsible to set the charging current as preferred. Obviously, all protections regarding max current, min current and any alarms from the car are correctly managed by the EVSE module.
In managed mode it's easy to:
1. easily set the minimum and maximum battery level
2. easily set the maximum charging current
3. when battery level is below minimum, charge at the max power permitted by the electricity meter (in Italy, alternates 90 minutes at maximum power + 27% and 90 minutes at maximum power + 10%, it's not possible to charge faster! The electrical system must be checked carefully when using maximum power, to avoid overheating and fires!!)
4. when battery level is between minimum and maximum, charge using only power from renewable energy from photovoltaic

Also, the max grid power can be adjusted to get the maximum from the grid. The chart below shows the case of Italy, where the max available power is P+10% forever, and P+27% for max 90 minutes every 180 minutes: charging power will be the highest as possible, regulating the charging power to get the maximum available power preventing disconnections. Charging power is updated every 6 seconds to take care about other building appliances.

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Charging electric car when a stationary battery is available

In case that a stationary accumulator is installed in the building, two cases are possible:
1. the DomBusEVSE grid energy meter is installed before the stationary accumulator/inverter sensor (mains power supply -> DomBusEVSE energy meter -> battery sensor)

2. the DomBusEVSE grid energy meter is installed after the stationary accumulator/inverter sensor (mains power supply -> battery sensor -> DomBusEVSE energy meter)

To explain these two cases, let assume that photovoltaic is producing 3kW, house is consuming 1kW, max power from battery is 5kW, max power from grid is 6kW

Obviously, a parameter set the max current supported by the cable, that usually is 32A, so the charging power is limited to 7-8kW in single phase.