I sent the following case to Tesla last week after a service center Seattle visit. They are escalating the case to engineering. I took pictures of the charge screens to corroborate this:
"I am currently charging at the Centralia supercharger. I arrived at 2:34pm with 10% SoC, outside temperatures in the mid 80s, driving a car that was well warmed up (3.5 hour drive to the service center this morning, several short charging spurts at the service center, then 2.5 hour drive [heavy traffic on I-5] to the supercharger here in Centralia), and I picked a stall that wasn’t being shared with another Tesla (I plugged in at 1A – no Tesla on 1B).
After allowing a few minutes for the charge to ramp up, my charge rate was only 50 kW at 13% SoC. At 20% SoC, I was charging at 52 kW. At 31% SoC, I was charging at 52 kW.
These slow charge rates prompted me to move to stall 3A. There was no Tesla at 3B. My car suddenly jumped up to 84 kW at 33% SoC. At 41% SoC, I was charging at 86 kW. For reference, 87 kW is the fastest I have been able to supercharge since last summer. Last summer, shortly after taking delivery of the car, I was able to supercharge much faster than that.
At 42% SoC, A model X entered and hooked up to stall 3B. From what I have read, the newly arriving Tesla’s charge rate should be throttled since I was here first. However, after the X hooked up, my charge rate plummeted to the 40 kW range. By 49% SoC, I was maxing out at 56 kW. By 59% SoC, My max rate was 49 kW.
At 60% SoC, it was now 3:14pm. I started charging at 2:34pm. That means it took 40 minutes to get a 50% charge.
Regardless of the throttling, I know that these speeds, even my max speed, is not normal. There must be some explanation as to why my charge speeds are so slow now. I have used many superchargers in 3 different states since last fall and, no matter the conditions, I cannot charge faster than 87 kW. Most of the time I am charging MUCH slower than that (as demonstrated by the case above)."