Home-made wallbox to charge my electric car! EVSE module, configuration and automations for the single phase or three-phase EV charger

[psubiaco (Paolo Subiaco)]

I’ve built an EV charging station connecting together the following devices:

• the EVSE module DomBusEVSE
• a contactor 2P 40A
• an energy meter
• a differential protection RCCB Type-B

It’s possible to add an energy meter connected to the main switch (to measure the grid energy), but as I already have the grid power meter connected to the domotic system, I’ve configured an automation to update the EVSE module when the grid power entity updates. In this way I save cost and power consumption.
To make a wallbox by yourself, a full knowledge about electric systems and power dissipation is mandatory!!

It works perfectly with Home Assistant, and permit to choose the source of energy:

1. only from the renewable plant (solar photovoltaic in my case)
2. adding 25-100% of power from grid
3. managed mode: a script can set the charging current in Ampere

I put the HA configuration for DomBusEVSE in github

Below the wallbox dashboard and a picture of the DIY wallbox.

[tomton68]

Thanks for sharing. This is exactly what I’m planning to do as well!

I came across this article: https://nissanelectricclub.nl/forums/topic/zelfbouw-lader-evse-wallbox-met-wifi/#post-13230, but your implementation might even be better.

I’ll dive into the topic and questions might pop-up

[psubiaco (Paolo Subiaco)]

@tomton68

I’ll dive into the topic and questions might pop-up

Feel free to ask any questions: I’m glad to answer you.

[tomton68]

Unfortunately the website is returning a Joomla error:
https://www.creasol.it/en/support/domotics-home-automation-and-diy/making-a-diy-homemade-wallbox-working-with-home-assistant

So no progress today

[psubiaco (Paolo Subiaco)]

Please retry now.

Making a DIY homemade smart wallbox working with Home Assistant

Thanks

[tomton68]

Meanwhile the car is charging! I can plug-in and it automatically starts charging and stops when the battery is full!

Now the challenge is to charge with a different amount than 8A, depending on the grid power consumption and production.
How to let the EVSE Module know the following statuses?

{{ states (“sensor.electricity_meter_power_consumption”) }}
{{ state_attr (“sensor.electricity_meter_power_consumption”,“unit_of_measurement”) }}

{{ states (“sensor.electricity_meter_power_production”) }}
{{ state_attr (“sensor.electricity_meter_power_production”,“unit_of_measurement”) }}

[psubiaco (Paolo Subiaco)]

Check the configuration at GitHub - CreasolTech/DomBus_ha: Configuration, entities and automations for Home Assistant using DomBus modules

[tomton68]

Yup, got it working with the following automation:

- id: '1694168853275'
  alias: EVWriteGridPower
  description: Als de waarde van het verbruik/productie veranderd, dit aan de EVSE
    laten weten d.m.v. een ModBus write actie
  trigger:
  - platform: state
    entity_id:
    - sensor.electricity_meter_power_production
    - sensor.electricity_meter_power_consumption
  - platform: time_pattern
    seconds: /6
  condition: []
  action:
  - service: modbus.write_register
    data:
      hub: dombus1
      address: 11
      slave: 227
      value: '{{ 65536 - states (''sensor.electricity_meter_power_production'') | float *
        1000 | int }}'
      mode: single
    enabled: true

[psubiaco (Paolo Subiaco)]

This is the connection diagram to make a three-phase wallbox.

The energy meters are optional, because usually you already have the energy meter connected to your system: in this case it’s sufficient a simple script to send the actual power from the existing W1 meter to the EVSE module, and you just need the EVSE module, 4P 25A contactor, RCCB protection and EV cable.
Automation is available at https://github.com/CreasolTech/DomBus_ha/tree/main/dombus/dombusevse

[psubiaco (Paolo Subiaco)]

Here is my wallbox 230V single-phase connected to the vehicle, charging with only solar power, and then solar+5500W (max 32A, 6800W in case of my car).
In this video the house power consumption changes quickly, so you can see that available power from solar (PV power - house usage) was 1600W, then 3800W.
YOUTUBE VIDEO showing how my wallbox works.

[tomton68]

I did meanwhile add the power meter SDM630 Modbus V2 to the ModBus. Took me a while to be able to change the baudrate of DomBusEVSE, since ModPoll is standard not available in Home Assistant. This article + 1:1 with Paolo helped me out:

Modpoll - An alternative to read modbus device registers on HASSIO

Hi, I want to share an alternative to HA modbus integration. I always had problems to integrate some device using HA modbus (error connection, incompatibility etc), so I tried to use a famous free binary called ModPoll (Free Modbus Master Simulator and Test Tool) and use it on HA to read modbus register. Simply follow these steps: Download ModPoll and extract the folder x86_64_linux (or other version, according to your system) Open File Editor on HA and upload modpoll binary file of step 1 i…

Now both devices with different slave addresses and same 38400 baud work perfect (car not at home at the moment ):