Forum Discussion
Groover
Mar 10, 2021Explorer II
RoyJ wrote:
https://tflcar.com/2019/08/tesla-model-x-towing-loop-adventure-x/
Here's TFL's Model X towing a 5k lbs horse trailer. At 25:50, 30 miles in, their cruising average is 896 Wh/mile. 3.7 times more power than empty. I've never seen an IC truck get 3.7x worse mpg with a 5000 lbs trailer, that's what happens when an EV is so efficienty to begin witt.
I'd guess an 18k lbs toy hauler is at least 2x that amount, or 1.8 kWh / mile. For a 300 mile day of travel, that's 540 kWh pack.
Still don't see how an 80k lbs semi can go 600 miles on a 1,000 kWh pack.
You have made some good observations and are hitting all around some of the answers to your questions without realizing it.
To begin with, a horse trailer doubles the fuel consumption of my 2016 F150. And that is with one that is relatively streamlined. A lot of trailers are not aerodynamic at all. Even those that are are not well matched with the tow vehicle in many cases. When my daughter replaced here bumper pull with a larger and heavier gooseneck trailer her fuel economy went up. I think that it because the gooseneck trailer is much closer to the cab and is better set up to stay in the slipstream of the truck. I can take that same bumper pull trailer and tow it behind my motorhome that is 12ft tall and 102inches wide and it has very little effect on fuel efficiency.
On that note, Tesla knows this well and is great with aerodynamics. Every picture that I have seen with a Tesla tractor pulling a trailer shows a combination that is well matched and equipped for low air drag. No toy haulers with external air conditioners, awnings, door handles, antennas and flat back end will be tolerated.
One of the largest air drags for ICE engines is cooling air. The Tesla semi just won't have that at all. What would have been cooling air will be very aerodynamically routed around the tractor. The power steering, AC compressor and air compressor will only run on demand instead of being driven all of the time. There will not be any fuel sucking exhaust filter regens. There won't be a massive cooling fan sucking 20hp when going up a hill. The oil pump will go away and the cooling pump will be much smaller. My neighbor tells me that 1/3 of his engine hours on his semi comes from idling while stopped. When a Tesla semi is stopped the only systems that will be running are some very efficient operator comfort items and, when needed, some LED lights.
Tesla is also going after rolling resistance by using super singles in place of duals, nearly cutting rolling resistance in half plus reducing air drag. Since the mechanical brakes will only be used very rarely Tesla might find a way a routing cooling air around them except when needed.
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