If you are wondering whether you can drive to Crystal Mountain and back in a Tesla without having to charge along the way, here's a quick overview of our trip.
TLDR: YES*, you can drive a 75kW Model X from Seattle or Bellevue to Crystal Mountain and back and not have to recharge.
The road from Bellevue to Crystal is roughly 77.5 miles, depending on the exact route you take, which makes round-trip to be 155 miles of "clean" range. We left from Downtown Bellevue on a full charge, which in a 75W Model X is equivalent to about 235 miles estimated range. We had 3 adults and two children, plus gear. The car was packed but not extremely heavy. The day was sunny and hot, road conditions clear. Plenty of charge to go on.
Since there were no supercharges en route to Crystal, nor were there any chargers at the mountain itself, I decided to put the car into a "range mode." It was not clear what the range mode would do to save battery, but there was no harm. More on that later.
On the drive from Bellevue to Enumclaw we went from 230 miles to 190, and from Enumclaw to the top of the mountain we went down to 120 miles. This expenditure was unexpected but reasonable. The second stretch of the road was basically all uphill.
40 miles spent from Bellevue to Enumclaw
70 miles spent from Enumclaw to top of the Crystal Mountain
Total: 110 miles spent to go from Bellevue to Crystal Mountain.
Even with this energy spending, we had plenty for the trip home. But, something pretty cool happened on the way home. We actually gained energy going down the last couple of miles of the Crystal road, and spent only about 15 miles of range going from Crystal to Enumclaw, and then maybe another 25 to get all the way home.
Total: 40 miles spent to drive from Crystal Mountain to Bellevue.
*We drove during the summer, and although the AC was on the whole way, it is my understanding that winter driving with bad road conditions and heating use up 25% more energy. Extrapolating that for our trip would mean additional 40 miles spent on the way. Still enough, but with less to spare.
It seems you can easily make it from Bellevue/Seattle area to the Crystal Mountain and back, without having to stop to recharge, as long as you have a 75kW battery or more. If you live up/down the 405, then you can always stop at the Bellevue mall for a lunch break on the way back and use the chargers inside the mall. It's an L2 but it should be good enough for all local charging; Bellevue City Hall also has a couple of L2 in the parking lot.
As per the "range mode," I can't tell if it was of much use without doing a second trip out, but I did notice the car was accelerating a lot smoother with it than without. If I were to guess, Tesla in range mode self-regulates the voltage supplied to its motors in a way that wastes less energy during accelaration by using car's own momentum, thus saving some battery along the way. It's just a guess though.
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