Lyriq charging rate at 80%?

What is the Lyriq’s charging rate towards the end, e.g. after 80% full?

The reason I ask is that I’d like to drive the thousand or so miles from Palo Alto in the SF Bay area up I-5 to Vancouver, BC in the shortest possible time while staying more or less with the traffic. I did that trip in 2017 in a 2017 Bolt Premier, taking 3 days albeit with some detours along the Oregon coast, Mt. St. Helens, and Lake Quinault in the Olympic National Park. Can I do it today in a 2023 Lyriq in 1 day with no detours?

In particular, is it better to stop charging as soon as the Lyriq is drawing less than 190 kW, or to let it charge a bit more in order to reduce the number of stops, or even a lot more?

According to GM, spending ten minutes at each station adds 76 miles while 30 minutes adds 195 miles. Assuming enough 200 kW chargers along the way, for 1000 miles the former needs 1000/76 ~ 13 stops taking 13*10 = 130 minutes while the latter needs only 5 stops taking 30*5 = 150 minutes to charge. At 75 mph the driving time would be 13 hours and 20 minutes. The former’s 130 minutes charging time brings that up to 15 hours and 30 minutes while the latter’s 150 minutes brings it up to 15 hours and 50 minutes.

If that was all there was to it, it would be better to charge every 100 miles or so than every 200 miles.

But this overlooks three things.

1. What is the additional time to drive from I-5 to the station and back, along with the time to connect up and so on?

2. Are there enough 200 kW stations, namely every hundred miles?

3. What does GM mean by ten minutes to add 76 miles? Obviously that can’t be ten minutes to bring the charge from 75% to 100%. So how low does the charge need to be before ten minutes will add 76 miles, and how low before 30 minutes will add 195 miles?

For 2, I checked and was surprised to find that there were enough Electrify America stations in Oregon for that, while in California and Washington there were that plus enough EVgo and Charge Point stations. So that’s not an obstacle to any approach, even the hundred-miles-per-charge approach.

For 3, I should use the last station available before I run out, so as to start the charge from a low percentage. This doesn’t seem to be a problem.

For 1, this is more interesting. The time required to take 13 trips to a station and back, plus connect time, could easily dwarf that for 5 such trips, suggesting that 200 miles is a better spacing.

But in that case, maybe 300 miles is even better, which would only require 3 stops assuming I leave Palo Alto at 5 am at 100% and arrive in Point Grey, Vancouver, BC at say 9 pm at 0% where I can charge to 100% overnight using Level 2.

Thanks to Plugshare, along with the apps for EVgo, Charge Point, and Electrify America, I have almost all the information I need to optimize the trip from Palo Alto, CA to Vancouver, BC. The one missing thing is the rate at which the Lyriq slows its charging as it approaches 100% full. If at 95% it is still charging at say 120 kW then 300 mile spacing between charges might turn out to be better than 200 miles.

So is 300 miles the answer? Or 250? Or 200? Knowing how charging slows as the Lyriq’s Ultium battery approaches 100% would help answer this.