Continuing the discussion from Installing EV charging for one unit in a 6-unit condo building:
It seems like it should be possible to add sensing for the current through the main breaker. With that the load that the car is pulling could be reduced only when necessary. It would add a little to the cost of the control system but not that much. It would not require additional power components.
You would need have a smart charging dock to do this. There are a few that have that capability but I am not qualified to recommend one. You can also program them to only operate during times of day when there typically isn’t much of an additonal load like in the middle of the night.
That is what you can do now as a work-around with what is currently available. If someone were to make a charger with that additional sensing of main current, it could, for example, reduce what goes into the car when the refrigerator is running.
While it’s certainly possible to add current sensing into the mix to allow higher amperage charging, it probably isn’t actually necessary outside of edge cases. For example, if we assume an EV efficiency of 3 miles/KWh and charging 10h/day, you get something like this:
| V | A | KW | M/10h | M/Y |
|---|---|---|---|---|
| 120 | 15 | 1.44 | 43.2 | 15768 |
| 120 | 20 | 1.92 | 57.6 | 21024 |
| 240 | 20 | 3.84 | 115.2 | 42048 |
| 240 | 30 | 5.76 | 172.8 | 63072 |
| 240 | 40 | 7.68 | 230.4 | 84096 |
| 240 | 50 | 9.6 | 288 | 105120 |
Even a pain vanilla wall socket will get you past the average annual mileage in the US. Sure, if you drive a Silverado EV 200m per day you’re going to need a big charger. But for most people, a 30A dryer socket would be adequate to keep 3 EVs charged on rotation even on relatively pessimistic assumptions of total charging time used and total mileage required.