I had a very frustrating charging experience on Sunday as part of my journey back to Toronto from Atlantic Canada. After L2 charging in Edmundston for 90 minutes, we limped toward the Rivière du Loup Supercharger. For a stretch of highway that we should have cruised at 110km/h, our average speed was 65km/r, average consumption 186Wh/km at -7.5ºC. 172m gained over many rolling hills, range mode on, heater off (brr). It was a tedious experience for my co-pilot, who had no prior first hand experience with electric vehicles. We arrived with 1% SoC, freezing cold, ambient temperature about -10ºC. I turned Range Mode off upon arrival. We plugged in at the SC, and the car gave no complaints and suggested a 1% to 100% Supercharging time of 1h20. I waited for charging to ramp up which it never did. I recalled other threads discussing the need to warm the battery prior to Supercharging, so for the first 20 or 30 minutes I wasn't too concerned. It cycled from 0 to 10kW at random (as others have described), and after 1h20 minutes on the Supercharger having gained only 1km rated range, I tried changing stalls to no effect. This was not the coldest temperatures I've attempted to charge in since owning the car, but it was my first very cold Supercharging experience. What felt strange, though, is that I have used L2 charging many times while quite cold soaked, and have never seen anything but full amperage/rated range charging. I pulled across the parking lot to a L2 charger, and to my surprise the car pulled the full 48amps, registering 48km/hr charging. My pack gained kms almost by the minute while I called Tesla tech support to seek further advice. They confirmed what was not at all intuitive to me: that L2 charging is a lot more effective at trickle charging than Supercharging. I have no idea why this would be the case. But if you find yourself in this situation and want to potentially save some time/grief, try plugging into a L2 charger if available, to bring up your SoC a few points while warming the battery, prior to Supercharging.