I’m not going to lie, I’m not huge on math. I did okay in highschool and faculty in math lessons, however I didn’t pursue a science, engineering, or different technical diploma. So, I’m most likely not the individual to go to if you’d like a deep have a look at the numbers behind a clear expertise. However I do know who to go to once I want these numbers, and a kind of individuals is Jason at “Engineering Defined.”
There are lots of people who suppose that Elon Musk is a little bit of a con artist. A few of them brief the inventory, a few of them simply don’t just like the man, and others have made an precise case. So, at any time when Tesla or SpaceX proclaims one thing new, there are all the time just a few individuals making an attempt to inform us that it’s unattainable, and thus most likely a rip-off.
That is the place Jason’s skillset (an precise engineering diploma) comes into play in nice methods. As an alternative of wildly speculating, Jason determined to place claims in opposition to the Tesla Semi to the check. And, now that extra numbers are out, he gave them a good deeper look. The outcomes are sometimes good for Tesla, however there are a few dangerous information objects.
Vary & Battery
He begins by masking the seemingly battery capability of the Tesla Semi. He doesn’t have the precise official determine (as a result of no person exterior of Tesla does), however some data that Tesla and Elon Musk gave out in the course of the supply occasion and on Twitter was sufficient for Jason to offer us an excellent estimate.
The excellent news? It’s seemingly that the Tesla Semi didn’t want a megawatt-hour pack. The effectivity is definitely adequate that they might get away with solely 850 kWh of battery cells, which saves Tesla a bunch of cash, preserves the battery provide for different autos, and is mostly higher for the setting.
He additionally took a very good have a look at Tesla’s 500-mile drive. One factor many viewers didn’t discover was that you could possibly have a look at the drive and see the speedometer. Tesla’s estimated vary of 500 miles is predicated on a 60 MPH velocity, which is necessary as a result of the automobile didn’t use its complete battery on the drive. A more in-depth look reveals that the speeds have been nearer to a 55 MPH common.
That is necessary, as a result of it additional backs his estimate of 850 kWh. They wouldn’t want the entire pack to journey 500 miles at 55 MPH.
In fact, he proves this. He takes the drag coefficient of the automobile, its weight, and each different issue he may get good numbers for, and comes up with a necessity for 800 kWh in a earlier video. He recalculates this for 55 MPH, exhibiting that you just’d are available in at solely needing 740 kWh to drag off this run. This leaves loads of room to solely use 93% of an 850 kWh pack.
Velocity
He then goes on to ask the query of what it will take to journey at a extra practical 70 MPH. From speaking to truckers and my expertise matching their speeds in some hypermiling experiments, most vehicles go 68–70 MPH, even in Texas the place they might legally go sooner. Why? As a result of trucking firms usually restrict the velocity to 68 to avoid wasting gas and cut back dangers.
To go that velocity would require about 1187 kWh, which is certainly greater than the Tesla Semi has. Apart from the beautiful strong case he made for an 850 kWh pack, 1187 kWh can also be greater than the bigger 1 MWh estimate many different individuals have been making. If he’s proper and it has an 850 kWh pack, the vary at real-world speeds is extra like 350 miles.
Jason then works to research the query of whether or not a 350-mile vary is sweet or dangerous. As Tesla identified, many routes (as a lot as 80%) are fewer than 250 miles, so the reality is that 350 miles can be simply high quality. Plus, add different knowledge (just like the annual mileage for many giant vehicles) and the 350 miles look higher and higher.
Weight & Hauling
One other knowledge level that Jason was ready to have a look at was a quote from a Pepsi government. They stated that the truck will haul a great deal of chips over 400 miles however that heavier a great deal of sodas will usually solely be hauled 100-ish miles. Apparently, some individuals have been utilizing the quote to speak trash in regards to the truck, however Jason says they shouldn’t be so fast to leap to such a conclusion.
This assertion, in addition to a number of others that he shares, don’t present necessary velocity context. It’s potential that the bigger vary estimates Pepsi has given can be for decrease speeds.
The burden of the battery itself is one other huge query individuals have had, and he had some perception there, too. He begins out with the burden of the Tesla Mannequin S, which is barely 100 kWh. Utilizing related numbers, he estimates the precise weight of an 850 kWh battery to be 10,000 lb at most. He says the burden might be much less as a result of the container might be not the identical weight as 8.5 Mannequin S packs.
One other query he checked out was how a lot cargo carrying capability this implies the Tesla Semi misses out on as a result of it’s carrying the burden of the battery round. Vans have solely a sure authorized total weight, so carrying round as much as 10,000 lb of battery means much less capability left for the paying cargo, proper?
He estimates the Tesla Semi’s tractor weighs about 8,000 kilos greater than a diesel-powered semi truck. However electrical vehicles are allowed to weigh 2,000 kilos greater than diesel vehicles, so the true penalty is barely 6,000 kilos. Then, contemplate that electrical motors are far lighter than a diesel drivetrain (huge six-cylinder turbo plus heavy responsibility transmission), so there’s a minimum of one other 2,000 kilos of weight financial savings, lowering the capability loss to solely 4,000 kilos.
He goes additional to have a look at the precise cargo weights that actual diesel vehicles carry. In fact, the Tesla Semi’s max load (which he figures to be round 44,000 lb) falls inside the regular vary of actual hundreds carried in the true world. Why? As a result of most vehicles are “cubed out” or full as a result of the trailer is packed to the highest and never full as a result of they hit the burden restrict.
The Conclusion: The Numbers Work Out, Naysayers Are Filled with Bull
The argument that the Tesla Semi’s tractor is heavier, and thus it’s ineffective as a semi truck, simply doesn’t help the burden of the numbers. It might probably tow virtually as a lot as a diesel truck. It has first rate vary for many makes use of. It might probably have each first rate vary and carry almost all the identical hundreds as diesel vehicles truly carry at this time. To argue that the Semi is a rip-off, you’d should argue that with the ability to carry 60–90% of real-world hundreds isn’t adequate!
He’s truthful, and factors out that there are nonetheless issues with a few of Tesla’s statements, however the precise physics of the truck do try.
Featured picture offered by Tesla.
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