TL;DR, using only what the car shows me while supercharging, my SR+ has a capacity* of 52.52688 kWh

**Technique:**

- Take a video of your screen while your supercharging session ramps up.
- When the display ticks up to your rated capacity per hour, read off what the power is at. This should indicate some gauge of what the car itself thinks the capacity is, right?

e.g. In a recent supercharging session I captured the following relevant frames from a video:

52 kW 385 km/hr

52 kW 386 km/hr

53 kW 386 km/hr

53 kW 387 km/hr

52 kW 386 km/hr

53 kW 386 km/hr

53 kW 387 km/hr

I have the SR+ with rated range of 386km, so from these few datapoints it would seem the car believes that 386km range = 52-53kWh (an hour of theoretical charging at 52-53kW (52kWh) should add 386km of range at 386km/hr).

Using this technique and A LOT more datapoints I managed to figure out that the car's internal number for efficiency appears to be between 136.000 Wh/km and 136.187 Wh/km.

Interestingly, roughly the mid-way point there of 136.08 Wh/km is equal to 219.00000 Wh/mi, so I'm kinda wondering if that's the set constant they're actually using internally on the SR+.

I couldn't narrow the range down any further because there are errors of +/- 0.5 kW and +/- 0.5 km/hr on the screen readouts, and I accounted for min/max on each of these errors to narrow my range. 136.187 Wh/km was the minimum of all of my maximum estimates, and 136.000 Wh/km was the maximum of all my minimum estimates, where a max estimate used the displayed kW + 0.4999 and the km/hr - 0.5, and a min estimate used the displayed kW - 0.5 and the km/hr + 0.4999.

Using 136.08 Wh/km x 386km rated range I get 52.52688 kWh.

*This is not accounting for any supercharging efficiency losses ... which I'm not sure if the readout is accounting for already, or not. Does anyone know? Furthermore, does anyone know what Supercharing losses are typically even if they are already accounted for?