Are Teslas Really That Efficient?

Опубликовано 25 марта 2020, 14:00

What Is The Battery-To-Wheel Efficiency Of A Tesla Model 3?
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How efficient are Teslas? Now I’m not talking about MPG ratings here, anyone can look up efficiency ratings. The 2018 Model 3 Performance is rated at 116 mpg combined equivalent; what I’m curious about, is how much energy that starts in the battery, actually makes it to the wheels to push the car forward? What percentage of the battery power goes towards useful work? This turned out to be quite challenging, but the results are fascinating; enjoy the watch!

Calculating Variables
For aerodynamic drag, air density was determined using an air density calculator plugging in ambient conditions (temperature, pressure, humidity) for when and where the testing occurred. This results in an air density of 0.00245183 slug/ft^3 (whatever a slug is). The drag coefficient was determined using the frontal area of the Tesla Model S and relating to the size and shape of the Tesla Model 3, estimated at 23.69 square feet (2.2 m^2). Actual velocity was determined using GPS, not the onboard displayed speed; a correction factor (approximately 0.97 derived from 72.7 mph = displayed 75 mph) is applied to aerodynamic drag to ensure displayed speed matches actual tested speed. Tesla provides drag coefficient at 0.23. The total weight of the vehicle includes my weight, for a total of 4,225 lbs. A coefficient of rolling resistance of 0.01 is used. The very best “green tires” of recent history are around 0.006 to 0.007. AllTyretests.com claims a Crr of 0.0096 for the PS4S tire, so we’re assuming 0.01. According to Continental via tirereview.com, “there is no longer any difference between summer and winter tyres in terms of rolling resistance” hence I’ve used 0.01 for all Crr calculations.

References:
Tesla Well-To-Wheel Efficiency
youtu.be/2rywz73vwKw

Car And Driver - Model S
caranddriver.com/features/a151...

Car And Driver - Aero Covers
caranddriver.com/news/a3016946...

Continental Winter Tire Rolling Resistance
tirereview.com/rolling-resista...

Michelin PS4S Rolling Resistance
alltyretests.com/michelin-pilo...

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