I have posted the Particle code here
. Everything is in that one file.
The code works, but it has not been reliable. It may be that I need to handle the Wi-Fi with more error-checking and retries, or I need to do more error-checking on the Leaf data received after the vehicle starts.
Some of the code is specific to the Wi-Fi remote LCD display, and some is specific to the OpenEVSE, to which I send a Wi-Fi command to stop charging, so these may not be helpful to others. There is also much debugging code in there, some turned off by commenting-out calls from the main loop (the last routine in the file), or by #if statements, also as shown in that main loop.
I have not been able to get back into this project for many months, so I won't remember anything about it and cannot answer questions.