Home made wallbox using Home AssistantEverybody using an electric vehicle wants to charge the car in a smart way:

  • preventing overloads
  • using only energy from photovoltaic, in Spring and Summer
  • maximizing power factor to get the highest charge efficiency
  • controlling and monigoring charging by smartphone/tablet/PC
  • integrating the wallbox in the home automation system, to get an efficient load balancing and accumulating energy in the car when energy price is lower.

DomBusEVSE is a charging module available with 2 protocols:

  1. DomBus protocol (proprietary) for Domoticz
  2. Modbus protocol (standard) for Home Assistant, Node-RED, OpenHAB, ....

It also works as stand-alone, in case that domotic controller is off-line.

Hardware requirements to make a DIY EV charging station

Making a home-made charging station is quite simple, but needs to know about electric systems and power: charging sessions are usually long and care must be taken to avoid overheating on connections and cables.

EVSE module is quite simple: it measure the power drained from the electrical grid, sends to the car a PWM signal to set the maximum charging power/current through the Control Pilot wire and read the vehicle status through the same wire.

The following items are needed to make a home-made charging station (with links with our store, but as standard devices they may be purchased anywhere):

  1. DomBusEVSE, that is the charging controller
  2. Protections: type-B RCCB is recommended
  3. Contactor, to enable mains power supply (2P for single-phase or 4P for three-phases) and EV cable
  4. Power meter to measure the EV power, energy, voltage, power factor
  5. Bidirectional power meter to be placed in the main switchbox to measure the energy exchanged with the Grid, if a power meter is not already available in the home automation system.

More info to make the wallbox are available in the DomBusEVSE page.

DomBusEVSE firmware details

More info about how the EVSE module works are available in the DomBusEVSE page.

Integrating DomBusEVSE in Home Assistant

Install the Modbus integration .

Fetch the configuration files from the github page dedicated to DomBusEVSE and Home Assistant and put them into the HA config directory. You can see configuration files for different modules, so you have to enable what you need and disable the rest.

If you know English, please check this page in English language because other languages will be confused by the unnwanted translation of some parameters name.

Keep note that:

  1. this EVSE can be configured in "Managed mode" (an automation can periodically set the charging current value, from 6 to MAXCURRENT): in this way the EVSE become stupid and let the external automation to manage charging and balancing through different EVSE connected to the same electrical system.
  2. normally EVSE is not configured in "Managed mode", but can be configured in Off (don't charge), Solar (Grid power = 0), 25% (use Grid power = 25% of MAXPOWER), 50% (use 50% of MAXPOWER), 75% and 100% (use MAXPOWER from grid). To work correctly, you have to:
    1. connect a supported power meter (DDS238-2 ZN/S for single-phase, DTS238-4 ZN/S or DTS238-7 ZN/S for three-phase) programmed with slave-address=3 and connected to the additional Modbus port of the EVSE
    2. if you already have a power/energy meter connected to the domotic system, use a simple automation to write the current power (in Watt) drained from grid (negative if sourced to the grid) to the Grid Power entity. Example is available in the file dombus/dombusevse/dombusevse_automations.yaml The grid power should be written every 2-6s during charging session.

For additional support, enter the DomBus telegram group.

Smart DIY wallbox for Home Assistant

Single-phase homemade wallbox

Home made smart wallbox working with HomeAssistant

Schematic for the home-made wallbox using DomBusEVSE module and HomeAssistant

Charging electric vehicle at really full speed and efficiency with home made wallbox working with Domoticz Home Assistant Node-RED ....

Three-phase home-made smart wallbox

Home made smart wallbox using DomBusEVSE, threephase, 11kW or 22kW (or less)

More info at https://www.creasol.it/EVSE