You are correct. In the event that there isn't a neutral present, the neutral and ground will just be tied together in the connection. At my parents house they have an old school 240/15 amp outlet with 2 hots and a ground. No neutral. In this case I will just tie the neutral and ground together. As far as the GFI functionality, you are correct, if I were to run the 240 jumper through the CT is should work. As of right now the charger doesn't like it. I haven't messed with it since yesterday. My mod to all of 20 minutes. I tried running my second hot leg through the CT and it didn't like it. I will work on it this week and let you all know. And yes, it will still cost $20. The current mod I'm using is 2 jumpers for 230 and the only cost involved was the 12/3 extension cable for the new tether and the 240/20 amp plug. Both of these were less than $20. If you were to use a nema 6 or 14 connector it would be quite expensive. The nema 6/14 connectors are $22+ per connector. This is kinda high if you ask me. Being that the unit is portable, I'm more in favor of the standard 240/3 wire 20 amp connector for $6. The twist lock is too expensive, and in my opinion you want the connector to come loose if someone were to trip on the cord or something like that. I wouldn't want stress to be placed on the J1772 connector on the car or the house and risk ripping the outlet out of the wall. Plus, cost is everything. It's just cheaper.
For those naysayers who think I'm doing wrong or something. I am sorry you don't like what I'm doing, or think that I'm an idiot. I am a degreed engineer, in the power field, I have my PE, I do understand the J1772 standard so if you don't like what I have to say here, don't post please. I am simply letting others know an easy way to get L2 charging on the go.
I earlier said that this wasn't a permanent mod, but after thinking about it I changed my mind. This crude mod could be permanent. Every time you plug in an extension cord there is 120@15-20 amps present at the end of the outlet. Everyone in the modern world is ok with this. My crude $20 mod does the same thing. There is one hot leg and ground always at the end of your J1772 connector which is no different than an extension cord. Since this is a portable charging unit and I am assuming you are using it away from your normal charging location, it would also be safe to assume that when you plug the ESVE in, you are probably ready to charge so the charger isn't just sitting there hot with nothing attached. In this case, the jumper mod is perfect. It's quick, easy your still protected by the breaker in the power panel in the house and its cheap. Using the relay that I've ordered is a more permanent solution just because it does't keep the connector hot. Using the jumper method, reverting back to 120 charging is all in an additional pigtail which would cost about $10 tops.
So if I understand you correctly, you mod is going to require a 4-wire power source H-N-H-G, so that you can tap off 120V from H-N to power the 120V control board? This is a cheap way to do it, but it will limit its portability, since a lot of 240V receptacles don't have a neutral wire.
I haven't taken mine apart, so I don't if what I'm proposing is feasible or not, but it seems a more straightforward method would be to just patch in a 240V-compatible switching supply for the controller. The current 3-wire input is 120V H-N-G. I'm assuming H-N are going through the CT for the GFI. So if you use a pigtail to connect H-H-G for 240V, the GFI will still work properly. No other jumper needed.
Would this work, or am I missing something?