Ok. What I meant was, what value or algorithm does the car use to determine a minimum arrival % before it starts suggesting mitigation strategies, ie charging stops.
It's been my experience on road trips that Tesla tries to get you to the next SC destination with at least 10% of charge. For instance, you have a very long gap on the highway so there is really only one choice for the charging stop you are at - stay there long enough to achieve 10% estimated arrival.
It's easy to see when charging because it won't tell you to go on until the next stop sees 10% - then it will tell you that you can continue your journey.
WHILE CHARGING, the only option you really have is to stay longer or not. The algorithm will take into account your car model, weather, elevation and some form of using your average speed over recent time to determine your projected energy usage. IF you have an exceptionally long gap to the next SC, it may tell you that you need to drive below a certain speed even with 100% charge.
Once driving, more factors come into play. At this point I don't quite know what it plans if it see that you are getting to the next station with less than 10%, but I think that is when you start getting speed warnings. Realistically, speed control is the only control you have right then. I don't think it cares how fast you are going until the estimated destination charge drops to 10% or less. I will sometimes drive faster if i see that I am going to arrive with 'too much charge', and I want to arrive at 10%.
Arriving at 10%, and playing with speed to achieve that, is desirable to the extent that you want to maximize charging speed, which for my car is fastest at 10% with the battery preconditioned. Arriving with 30% gets me a far slower charge rate. So here are two ways to do this, and some implications:
1. Charge 'extra' to always have lots of buffer for unexpected conditions. Perhaps a storm, or a road closure. Let's say you are arriving at a SC at 30% and charging to 80%.
2. Arrive with 10% buffer and charge to 60%.
In both cases you add 50% charge. But the first option is going to be several minutes slower than the second option, and you will add those extra minutes to your trip with every charge stop.
Even better, assuming you have SC's in the right places, might be to charge from 10% to 30% and stop twice as often. More stops, but much quicker stops. This is actually the fastest way to road trip, if the SC locations (and speeds) are conveniently sited.
