Based on a Mainpine controller, internally an ESP series microcontroller, possibly reflashable to Tasmota type code. Would do the MQTT part, not sure how to do the EV control part. This should have had a MCB / RCBO fitted as well as an isolator, although the feed is from a 16A socket with it's own MCB.

Later controller built with https://www.openevse.com/ parts, this supports MQTT over wifi or a wired ethernet. More to come…

After the above Mainpine unit went faulty, I built a replacement using an EVSE controller module.

Components used (L to R)

• 100A double pole disconnector to isolate the unit. This is fed via a 16A industrial connector and 20A MCB in a consumer unit, it would be better to have a 16A MCB in it too, but there wasn't space and the 16A socket should always be fed via an MCB anyway. This whole consumer unit is protected by an RCD.
• 20A contactor driven by the evse module, this provides a 240v output but at low current. The double pole contactor isolates the EV unless energised, so until the cable is connected, the cable is unpowered.
• EVSE module (The blue bit marked MinMax visible is the AC to DC converter). This is WiFi capable, but I have disabled it because….
• Ethernet module connected to the EVSE unit. This is used instead of the WiFi.

The round object at the top is a current transformer to measure the current the EV draws.

The LCD module is driven from the EVSE and changes colour depending on the charging state of the module (Green - connected but charged, red - charging)

This is a simple flow from NodeRed to show data which can be extracted from the EVSE module.

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