how many miles at a constant speed does a charge last
Depends on your Watts per Mile. There are too many variables to give you a definite answer. Here are a couple calculations;
250wpm - 85,000/250= 340 miles per charge (Range charge)
250wpm - 68,000/250= 272 miles per charge (80% level)
350wpm - 85,000/350= 243 miles per charge (Range)
350wpm - 68,000/350= 194 miles per charge (80%)
450wpm - 85,000/450= 189 miles per charge (Range)
450wpm - 68,000/450= 151 miles per charge (80%)
Your mileage will vary, based on your driving style (wpm)
Watthour per mile. Not Watts per mile.
Might feel nitpicking, but there is a difference, that's not just a typo. Watt is unit of power, Watthour is unit of energy.
yeah, my bad.
The math is still correct, regardless.
Of course, the mileage will actually be less, since not all 85kWh can be used with certainty. See Rod and Barbara's thread.
That's not public thread. Access denied.
The EPA rated the Model S with 85kWh battery as having 265 miles of range on a "full" charge. I would say that it's pretty easy to get 220 miles without even really trying. I also don't think it's that hard to get 240 or even beat the EPA's testing if you do try to drive with the intent of being more efficient.
For the EPA's test, they averaged about 308 Wh/m. On my daily commute, I usually get around 290 Wh/m. Sometimes I can even to much better, getting 260-270.
There was someone that drove over 400 miles in single charge. Beating EPA isn't hard if you try to drive with range in your mind and if conditions are not bad. Speed kills range, just slow down if you want more range.
The 400+ mi. trip was at 25 mph, hyper-hyper-miling, on flat roads in Florida. No one should expect to see anything much over 300 mi. in real world usage.
Not much over, but over never the less. That's a lot better than EPA rating. 400 mi was just to remind that 300 is not the max, not even close.
Just to add to the database,
Yesterday I did a range charge to 266 rated miles. I drove into Spokane (from Cheney) for lunch and continued on to Kellogg,ID and then to the Idaho-Montana border at Lookout Pass. It was rainy or at least drizzling the whole way, and my mileage suffered as a result. The roads were wet and the weather cooler than anytime since the beginning of summer.
The trip took me over Fourth of July pass which has an elevation of a little over 3000 ft. Kellogg has an elevation of about 2300 ft, Cheney about 2400 ft and Spokane about 2000 ft. Lookout Pass has an elevation of about 4800 ft. The distance one way was about 110 miles. On the way home, I stopped in Kellogg for about an hour.
I took a long cut and arrived home with about 8 miles of rated range left. I was given the message that the battery would get cold if I didn't plug in immediately. I went in to feed the dogs and then came out to continue driving around Cheney to finish draining the battery. I was less than 100 feet from my driveway when it reached 0.
When travelling on the highway, cruise control was set at 62 mph, although I dropped the speed to 55 on the climbs.
Below are the results.
As you can see (assuming the photo got inserted properly) my total consumption was 75.8 kWh for the trip with a total distance traveled of 247.6 miles with average rate of consumption at 306 Wh/mi.
The total consumption was not far off from that posted by Rob and Barbara in their thread about new information.
If my consumption rate matched my lifetime average, I could have traveled 258 miles on the energy used, and 300 miles if I could have had the conditions to obtain an average of 252 Wh/mi.
Darn.. The photo didn't take.
Hosted url, <img src="URL" width="600">
Oops, I see you got it. Width 600 matches the column size.