[shiftpgdn]

Using Texas as an example:

10-80% on a Model S/X is 70kwh. Rate billed to customers will vary from 30-50c/kwh at time of charge. Spot in Texas typically ranges from 5c to 15c/kwh. Assuming charge equipment is fully depreciated all they need to pay is maintenance and network cost, which is marginal across a bank of 20 chargers.

70kwh x 25c = $17.50.

[sib]

Using California as an example, they are charging $0.12 / kWh more for non-Teslas than for Teslas. I don't see any reason to assume that delta would be different in other locations.

Since the Tesla-Supercharging business is running at break-even, you're looking at something like $8.40 for a non-Tesla adding 70kwh.