That's right. I make no pretense of my analysis being an in-depth one. As I said: Napkin math.
Pushmi,
if you look at the average mpg of the latest diesel semis, you can back into the kwh per mile for the Tesla Semi.
Navistar did a test of 4 trucks in Canada - they got 7.75 mpg average - pulling 65k lbs, they averaged 46.5 mph (100 kmh limit in Quebec?).
Tires were around 0.005 crr.
cd for those trucks is around 0.55 based on DOE data on previous tests.
At 42% BTE (which is the current average for a new Semi / EU data / same engines in US) and 40.3 kwh conversion, that's 2.18 kwh / mile.
About 25% of that goes to various losses, including inertia/braking, auxiliaries, etc.
[btw - Martin Williams and David Green posts above are off on AVERAGE numbers and engineering details, e.g. the Semi has a clever 2 speed axle set-up with a deep starter gear and a cruise gear. You only need <100 kwh to pull a semi on a flat road at 60 mph; again, see DOE numbers. Benchmark for auxiliaries is around 5 kwh on a 2018 ICE semi - see ICCT data for EU trucks - the Semi will probably be lower because you have zip for the air compressor and alternator. As we all know, one has to be careful not to confuse long term AVERAGES with the energy use for one trip across the desert or up over the rockies].
From all this you can triangulate using DOE and IEA data (and by doing the raw calculations) what the air resistance losses and rolling resistance losses are, and get to an average energy use number for the Semi that matches what Tesla has released, no problem.
That's possible. There have been suggestions this truck won't do well climbing steep mountain roads, and if so the Rocky Mountain region would be off-limits.
At any rate, I think it's safe to assume the Tesla Semi Truck will not have a multi-gear transmission. Will that limit its maximum grade? Well yes, but then diesel semi trucks are also limited to a maximum grade, altho it may be a different figure.
Entirely incorrect. About 90% of semi loads are less than maximum weight. Most loads, by far, have space/volume rather than weight as the limit. If Tesla's market is limited to that 90%, that's not much of a restriction! The restriction on range is a much bigger limit, but even there, the majority of freight hauling runs are less than 500 miles.
Let us please remember that the Tesla Semi Truck does not have to replace 100% of diesel semi trucks on Day 1 of sales. It will be quite enough if that truck can get a firm toe in the market, and prove that BEV semi trucks can compete successfully with diesel semi trucks for over-the-road freight hauling, even if it's only on certain routes and in certain regions. As BEV tech continues to improve, so will the ability of BEV semi trucks to compete.
The figures for charging a 2 MWh battery (actually, my estimate was 1.8 MWh) are rather irrelevant to the Tesla Semi Truck, since Tesla is only claiming a 500 mile range for the long-range version, not the ~750 miles I assumed in my "Napkin Math 1.0" analysis.
Tesla has cited a price of 7¢/kWh for electricity for charging its Semi Trucks, and it's probably no coincidence that this is very slightly more than the average industrial rate for electricity in the USA. I infer that Tesla will be restricting installation of its "Megachargers", as it calls them, to industrial areas where high-power hookups are already available.
This FUD that an electrical substation will need to be located right next to every Megacharger is pretty silly. Large skyscrapers can draw up to 10 MW, and a single electrical induction furnace can draw up to 42 MW! Estimates for the draw of a Megacharger range from about 1.2 MW to 1.4 MW. It has been speculated, based on the number of holes in the plug for the Tesla Semi Truck, that it will charge at 800 volts, so that will reduce the need for large cables as compared to the 125-145 volt charging of Tesla Superchargers.
Well, we can just add that to the growing list of subjects where you deliberately choose to ignore facts. The real world doesn't care if you believe it exists or not.
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