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Electric Vehicle Technology Roadmap And grid integration April 27th, 2011 JB Straubel

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I'm still trying to sort some of that out, too. The information presented seems to be similar to what's in the third chart in this blog: Roadster Efficiency and Range | Blog | Tesla Motors

The aero drag does seem to be about what that chart shows for 55mph. But the tire friction seems notably higher at either speed. Drivetrain seems a little higher (if you add all the pieces together in the older chart). Maybe it's updated for Model S instead of the Roadster?

What really puzzles me is the HVAC. Why is wh/mi less for city than highway? If they HVAC output is set the same (maybe that's a bad assumption?) you'll use more energy per mile at lower speeds, but the chart shows the opposite.
 
...What really puzzles me is the HVAC. Why is wh/mi less for city than highway? If they HVAC output is set the same (maybe that's a bad assumption?) you'll use more energy per mile at lower speeds, but the chart shows the opposite.

HVAC also used to cool the battery pack which otherwise gets hot during high power output?
 
I'm still trying to sort some of that out, too. The information presented seems to be similar to what's in the third chart in this blog: Roadster Efficiency and Range | Blog | Tesla Motors

The aero drag does seem to be about what that chart shows for 55mph. But the tire friction seems notably higher at either speed. Drivetrain seems a little higher (if you add all the pieces together in the older chart). Maybe it's updated for Model S instead of the Roadster?

What really puzzles me is the HVAC. Why is wh/mi less for city than highway? If they HVAC output is set the same (maybe that's a bad assumption?) you'll use more energy per mile at lower speeds, but the chart shows the opposite.

My understanding is that the city cycle involves a fair amount of accelerating and braking. While you do recover energy through regeneration instead of braking, there is an unavoidable loss each time you do it. The absolute best mileage is when crawling along in traffic that's doing about 20 mph but doing it steadily.
 
It means they are very resistant to rolling.

Huh? The opposite... They roll more easily. I don't know if either of you are joking.
The stock Yokohama tires were considered low(ish) rolling resistance, so I don't know if the new ones would be any better.
Rolling resistance contributes to wh/mi efficiency and maximum range per charge.
 
Huh? The opposite... They roll more easily. I don't know if either of you are joking.

For the record, let me state: :tongue:

In all seriousness, I have compared long trip power consumption between Yokohama AD07 and Toyo T1R and didn't find any detectable difference. Purportedly the AD07 has low rolling resistance but the T1R's were just as good.
 
I have been looking at tires recently and the difference between a manufacturer's standard tire and higher efficiency tire is less than one percent milage difference. This would not be easily measured by an individual. I am not sure that it should impact a individual's tire choice unless every thing else is equal.
 
Here's the thing: low rolling resistance generally means poor traction, apart from minor tread design choices and whatnot. So the tire losses in that chart from Mr. Straubel are pretty much inevitable.

Only way to really avoid that is to put the car on rails, but then it's a train :)