1. I usually configure my car to a max charge of 90% which yields 250 miles. Is that low for a 90%?
2. If i charge to the max 100% and immediately take off what would that charge be in miles on a 2020 Model 3. Does that degrade the battery performance in the long run?
Can i make it 225 miles?
I'll assume you have a 2020 LR Model 3 (not Performance), starting with rated range of 322 miles. If it's Performance, please disregard below, though if you have a Performance showing 278 miles vs. the original 299, it's arguably a better case (though your tires would hurt you), since you have more energy with 278 miles in a Performance 20" than you do in an LR with 278 miles.
1) Yeah, 250mi@90% suggests 278 rated miles which is fairly low relative to your starting capacity of 322 miles, so you have lost about 14% capacity.
2) You'll have about 278 rated miles, which is 67.2kWh. No, charging to 100% won't matter. As you can see from your results so far, rated range loss is fairly unrelated to how high you charge your battery - it's probably a factor, but a very minor one, based on available evidence. Time is really the biggest factor as far as I can tell (and random results/birth day of the vehicle).
3) From 100%, your battery has 67.2kWh available to use, but only 95.5% of that to 0%, or 64.2kWh. So to go 225 miles you'd need to do better than about 285Wh/mi (actually better than 282Wh/mi due to uncounted losses). That would get you there with 0% indicated, with 4.5% of your energy remaining (again,
0% indicated), or 3kWh (this is the buffer, which you should never count on using).
This should be just doable in a long range starting at 100% with 278 miles. The car will likely tell you to slow down to make it to your destination at some point (it tries to get you there with 5% or more remaining). If you tuck in behind someone (max following distance) for extended periods that would help. You should definitely be able to make it at 65mph, but you'll probably be able to make it at 75mph with some traffic, as long as there's no headwind or other bad conditions - or if it's an uphill leg.
You'd have to give details on the actual leg. If you lose 2000-3000 feet on the leg 225 miles would be absolutely no problem at all, because that would give you an extra 3-4.5kWh to work with (though the reverse would be very difficult).
Anyway, I'd explore other bailout options on that leg on ABRP (A Better Route Planner) or similar. You can't guarantee the conditions you'll encounter (if it's raining and windy you'll probably never make it). So you need to have options.
This is an example of a situation where you'd really like a car with the original capacity! You could make it there at 330Wh/mi, which means it would be no problem except in awful conditions (cold, windy, rainy, etc.). Unfortunately, this is not how EVs work - they always, without exception, lose capacity.
abetterrouteplanner.com
teslamotorsclub.com
