Early 2021, i purchased an used Smart ForTwo Electric - amazing little machine!
And i was given a free basic EVSE with it.
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 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.
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.
Translating these messages is quite simple with node-red.
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.
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
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...