Tesla Efficiency
Posted by Max Dunn Thu, 19 Mar 2009 19:39:00 GMT
I admit it – I am a numbers geek. I love to play around with numbers and think about them, and no more so than with electric vehicles. So imagine how happy I was too see some fantastic numbers about the Tesla Roadster!
The first of these graphs shows how much energy it uses at different speeds. The fact that energy goes down to a certain point is not surprising – all cars have a sweet spot where they operate most efficiently – but what is surprising that it is about 20 MPH versus about 55 MPH for gas cars. Another interesting point is that at 65 MPH the Tesla uses about 280 Wh per mile. This is measured from the battery to the wheels, so adding in the charging losses will decrease it to about 3 miles per kWh, which is the figure I normally use.
Another interesting chart shows the power versus speed. The increasing slope is expected since air drag is proportional to the square of the speed. So for instance, it takes 10 kW to go about 48 MPH but if you add 50% and go to 15 kW, you only increase the speed to 60 MPH.
Finally, this last graph is interesting because it shows the different losses on a car, from the rolling resistance of the tires to the drivetrain losses:
I hope you enjoy these numbers as much as I do!
(Reference: Roadster Efficiency and Range)