My home-made wallbox to charge the electric car!

[psubiaco]

I've made an EV charging station connecting together
* the EVSE module DomBusEVSE
* a contactor
* 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 Domoticz, I'm using a simple script to send the current grid power to the EVSE module. 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 Domoticz, 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 Domoticz script can set the charging current in Ampere
This is a video showing Domoticz panel, including the wallbox controls and my car controls.
Video: https://youtu.be/m_n_A4lo9Gw

This is the picture of a self-built wallbox.

creDomBusEVSE_wallbox_photo_domoticz.jpg (146.46 KiB) Viewed 1188 times

[kiddigital]

Impressive!

[psubiaco]

This is the connection scheme to connect the EVSE module to contactor, protection, energy meters.
The DombusEVSE module works perfectly with Domoticz, through the plugin downloadable at https://github.com/CreasolTech/CreasolDomBus
Once configured, the charging station works with and without Domoticz.

dombusevse_wallbox_domoticz_schematic.png (321.8 KiB) Viewed 1106 times

[willemd]

Impressive.

I am reading and following your warning:
To make a wallbox by yourself, a full knowledge about electric systems and power dissipation is mandatory!!
I am staying far from it, I am more a software person.

I am planning to use the creasol software for interfacing to my car soon.

[tux21]

Hi Paolo,
Thank you for sharing your stuff, it looks pretty good! I'm close from use it in my system, would I have few questions please?

I'm using Domoticz obviously and offgrid solar system based on Victron components. I'm able to read current solar production, SOH of my home battery, Inverter power, SOH of my car battery which is Nissan Leaf 1st gen etc. Leaf has 1 phase charger able to deliver max 3,6kW.

And now the questions.
Is the system able to change charging current fluently from 6 to 16 amps? Or possibly in steps 6, 10, 16A based on solar production and/or inverter load?
Is the system able to switch to grid when it reach previously set SOH of home battery to not drain it to zero at the evening? I have 10kWh home battery while Leaf has 24kWh and here is cheaper night tarif starting in the night from 2AM. So for example my use case is connect the vehicle, let it charge till home battery reach for example 40% SOH, stop charging, wait till 2AM, switch to grid, switch to 16A and continue witch charging from the grid.

Thank you,
Jiri

[psubiaco]

Is the system able to change charging current fluently from 6 to 16 amps? Or possibly in steps 6, 10, 16A based on solar production and/or inverter load?
Is the system able to switch to grid when it reach previously set SOH of home battery to not drain it to zero at the evening? I have 10kWh home battery while Leaf has 24kWh and here is cheaper night tarif starting in the night from 2AM. So for example my use case is connect the vehicle, let it charge till home battery reach for example 40% SOH, stop charging, wait till 2AM, switch to grid, switch to 16A and continue witch charging from the grid.

To answer Jiri questions:
* the system is able to change the current from 6 to 16A (or 32A) in 1A step.
* the charging current is chosen base on a energy/power meter connected to the grid: if you already have a power meter that measure the power exchanged with the electrical grid, you can use a simple script to pass this value to the EVSE.
If you have an offgrid system, you can put the wallbox in "managed" mode and use a script to pass the wanted charging current to the EVSE: for example, instead of charging 2000W to the battery you can set the EVCurrent device to 8 or 9 Ampere. Also, you can set the charging current depending on the house-battery SoC and EV battery SoC : it's up to you to decide how much power to use in managed mode.
* when house battery SoC is low, you can decide to stop charging, or switch to grid by and set the EVCurrent to your preferred value (you must have a power meter to avoid overload on grid power).

Script example for your offgrid system:
IF EVState changes from Disconnected to Connected (car plugged) => if time > sunrise and time < sunset => set EVMode to "Managed" and set EVCurrent to 0 (do not charge) or between 6 and EVMAXCURRENT (16A in your case) based on excess power from photovoltaic, house battery SoC, car battery SoC.
If time==sunset => EVMode goes Off
if time == 2AM => EVMode goes 100% (use 100% of power from grid, to maximize the power factor) and send the grid power value to the "Grid Power" virtual device to let the EVSE know how much power is drained from the grid preventing overloads

I don't know if it's clear, but in case don't hesitate to ask again.

[tux21]

Hi Paolo,

Thank you for your answer. Is there a way how to easily transfer dombus protocol over the air? Using ESP32or something like that?

Thank you, Jiri

[HvdW]

Hi Paolo,
Great! Thanks for sharing.

[psubiaco]

This is a dashboard for DomBusEVSE wallbox using HomeHabit app for Android/iOS, showing a charging session using only energy from photovoltaic and adding 25/50/75/100% of available power from grid. It's possible to see that increasing the charging power, the Power Factor increases (as like as charging efficiency).

homehabit2.gif (217.03 KiB) Viewed 947 times