EVSE Charger - reloaded

The quest for the perfect inexpensive EVSE

EVSE Charger - reloaded

Early 2021, i purchased an used Smart ForTwo Electric - amazing little machine!
And i was given a free basic EVSE with it.

The ugly uninteresting thing.

Without thinking much, i opened it up. Amazingly, it had a 32A 3-phase contactor, and some sort of EVSE controller. After digging around, i found the supplier - it's referred to as "evse-wb", made by some dudes from Czech Republic.

It speaks modbus, and after poking around, i found out about an ESP8266 capable firmware for making this EVSE smarter. It's called the Simple-Wifi, and talks modbus with the EVSE. https://github.com/baycom/SimpleEVSE-WiFi

But they mostly switched to a closed source ESP32.

After taking the EVSE apart and putting it in a roomier enclosure, time to add,

  • Shelly 3EM - 3 phase energy monitor
  • ESP8266 for enabling wifi on the EVSE - original version here
  • Display for monitoring energy consumption.

Enabling wifi is plug and play. Here's the pinout.

e-paper energy monitor display

MQTT enabled epaper display

This was not an easy one. I had a Wemos 2.13 shield laying around and after reading about epaper templates on hackaday, suffice to say i was intrigued.

This was mostly plug and play - except that this display wasn't natively supported.
For future reference, this was what worked.

Then it was a matter of doing a layout and testing was made easy with some clips.

After soldering everything to perfboard, i had the basic setup ready.

Inside, left to right: epaper, epaper controller w/ 5V PSU. shelly 3EM, contactor, evse-wb and simple-evse ESP8266 controller.

Outside it was way cleaner.

This has became quite a mess.

  • Shelly grabs power measurements;
  • Shelly connects to my OpenWRT router which is connected to the building LAN, and VPNs home all measurements via MQTT
  • MQTT (mosquitto) is read by emoncms server
  • emoncms accounts for all measurements, history, dashboard, et all
  • Home-Assistant connects directly to emoncms API. Why this way? we have 4 daily tariffs and emoncms makes this easy.

For displaying everything, i use node-red for reading mqtt values back from emoncms and sending them back to the epaper display.

top - sending images to server; bottom: reading them back and rewriting them to the epaper display

Translating these messages is quite simple with node-red.

Translatting shelly mqtt to emoncms

So, all good and done project, right?

Adding RFID and MQTT

We're not done yet

Original firmware had built in support for PN532 based readers.

I started poking around with the source code to implement mqtt and ocpp to the simple-evse - since i'm on a shared electric panel and soon we need to load balance all EV chargers.

But i noticed an interesting fork for this same firmware. MQTT works out of the box, and there's preliminary support for microOcpp (formerly ArduinoOcpp).

Adding RFID was a matter of connecting all the cables together and burning the firmware. This second ESP8266 is a Wemos D1, which grabs power from the epaper's ESP32.

Stitching everything up

As of today

I obviously need a new perfboard and to scrap all the jumper cables. But done is better than perfect. I'm now a proud owner of a 11kW smart charger that costed nothing (other than the epaper and the wemos D1 which i already had laying around).

Now for implementing the rest of OCPP...