Let's start with your first scenario. If the model 3 will average 200kW for the first 50% and average 155kW for the first 80% or the Audi averages 155kW for the first 50% and 150kW for the first 80%, I would definitely skip the charging stop at 50% and move on to the next one at 10% in my model 3 and I would arrive before the Audi. Is that agreed?What if you were traveling, wanted to stop to use the bathroom, grab a snack, get a drink, etc., but you were at 50% to 60% battery? In the e-Tron's configuration, your vehicle would add just as much energy as it would if you purposefully postponed your stop for another hour or two just to get down to 10% battery.
In other words, if your 500-mile trip required 30 minutes of charging to complete, you are much more limited with the Model 3's charging curve. With the Model 3's charging curve, you need to plan your charging stops around arriving at a 10% to 20% battery in order to achieve that 30 minutes of total charging time. With the e-Tron's charging curve, you can chose to stop for 30 minutes at almost any point along that trip that makes sense to you without any sort of penalty.
So right now, we are still in the innovator stage for EVs as far as the Diffusion of Innovation curve is concerned. In order to push into Early Adopter phase, we really need to stop requiring people to make concessions on behalf of the vehicle or technology. While it's okay for EVs to have inherent strengths and weaknesses, we need to get to a point where consumers do not need to significantly adjust their behaviors or preferences just to suit the requirements of the vehicles. Right now, most of the Tesla owners I know who take long trips fall into one of two groups: They either already liked to travel by making numerous short stops at specific predetermined intervals, or they adjusted their behavior and now find it an acceptable way to travel. Many customers won't be as tolerant as the latter group.
- Make two 15-minute stops or three 10-minute stops? Sure, pretty much at any point you want to.
- Drive down to 5% and make a single 30-minute stop? That works.
- Stop just an hour into the trip for a quick bathroom/coffee stop? That works too.
My entire position is that with a charging rate curve that has a sweet spot, wherever it lies in the % of battery range vs. a straight line rate curve that never wavers more than 3% from the peak generally will be superior to efficiency with the following caveat.
Level 4 charging stations are spaced around 75-100 miles apart.
The comparison between the model 3 and the Audi is a bit unfair to the Audi as it's peak and average at ~150kW is woefully short of what the Model 3 is capable of to the point that the Model 3 doesn't get below 150kW until around 45% which is about 15 minutes in. So a 15 minute charge in the Audi at 60% battery will get me 50 miles and the Audi at 50% remaining has only gone 110 miles so let's bump it to 30 minutes since there's no real taper penalty. I've now added 100 miles to the 110 I've driven. Let's run the Audi down to 10% which I've now covered 310 of the 500 miles and pray that there's a working 175kW charger available when I get there and we do it again. This time you might as well charge all the way to 100% again, since there's to taper penalty and I need the full 220 mile of a full battery to get to my destination. This adds another 45 minutes of charging. I've now charged for 75 minutes in the Audi to go 500 miles.
The model 3 drives to 10% with a pee break for 10 minutes somewhere along that journey with no added miles. That puts me at 290 miles covered. Charge for 15 minutes adding 180 miles but I really need 230 miles to be safe so rather than stop again, I'll take a hit on taper and charge for an additional 10 minutes. Now I can cover the 500 miles and only stopped once required for 25 minutes and 10 minutes for comfort. 35 minutes vs 75 minutes.
This highlights my leaning towards using the charging curve to your advantage vs. your preference to not having to think about when is the best % of battery to charge as we all currently do. Bolt owners and Tesla's. We already do this. But you are correct that if the charge rate is a flat line, charge whenever you have the opportunity makes sense.
One last note on the Tesla charging curve, my example above is assuming that the area under the curve is exactly the same for the two examples. Meaning that if it allows a peak of 250kW, then the taper will drop such that the average for example may be 175kW 0%-80%, the flat line rate would then be 175kW throughout the 0%-80% range. As I mentioned earlier, my choice of planning to take advantage of the peaks only really works if I have ubiquitous, reliable, optimally located level 4 chargers on route.
Now the Porsche, if it can charge at 350kW from 0% to 80%, no Tesla can touch that rate.