Since Tesla’s reveal of its new Semi and Roadster models, many technical analysts have been left scratching their collective heads.
How can Tesla promise performance metrics far exceeding what’s currently physically and economically possible?
According to one analyst, it may not be a matter of what batteries can do now, but what they can do tomorrow.
Bloomberg compiled a list of four seemingly impossible claims made by Musk during the reveal of the Semi and Roadster.
Those claims include the Semi’s 500-mile range when hauling 80,000 pounds, the Semi’s purported 30-minute charge time for 400 miles of range, Tesla’s guaranteed charging rate of 7 cents per kilowatt-hour for Semi customers, and the Roadster’s 620-mile range.
Bloomberg then attempted to reconcile each claim with reality.
For the Semi’s claimed 500-mile range, Bloomberg estimates the necessary 800 kilowatt-hour battery pack would weigh over 10,000 pounds and cost more than $100,000.
That last figure is important as Tesla has priced the truck at $180,000. The cost of the battery leaves Tesla with $80,000 for building the rest of the truck.
To put that in perspective, a typical Class 8 truck costs between $100,000 and $125,000.
However, Bloomberg believes Musk is banking on a significant reduction in the price of batteries before the Semi begins duty for customers in early 2020.
“By the time Tesla gets large orders, batteries should cost considerably less,” says the Bloomberg article.
Juicing up such a large battery for 400 miles of range in 30 minutes is well beyond the capability of any current charger.
Salim Morsy, electric vehicle analyst at Bloomberg New Energy Finance, was blunt regarding the Semi’s charging stats.
“I don’t understand how that works,” said Morsy. “I really don't.”
Tesla’s current Supercharger, which provides 180 miles of range to a Model S sedan in 30 minutes, has a power output of 120 kilowatts.
Using those numbers and Tesla’s quoted Semi charging time, the company needs to develop a new charger—currently dubbed Megacharger—with an output of 1200 kW, Bloomberg finds.
Can Tesla do that? Maybe. And if it can, the new Tesla Semi will be able to perform the duties of nearly two-thirds of the Class 8 market, said a representative for one of the company’s largest shareholders.
Back to economics, Tesla promised a 7 cent per kilowatt-hour rate for Semi owners, which could represent a massive cost saving measure for operators—more than $30,000 a year for some.
Still, that promise puts Tesla in a pickle. How can Tesla sell electricity at that rate when it costs almost $1 per kilowatt-hour to provide it today through its Supercharger network?
Morsy thinks this problem will be solved by where chargers are placed and how they pull electricity from the grid.
As Bloomberg explains, Tesla could place chargers at truck terminals where electricity is charged at a lesser commercial rate.
Additionally, Tesla can leverage its stationary battery packs to pull electricity from the grid throughout the day without causing usage spikes. Trucks would then pull power from those packs for their own use.
Morsy estimates this could bring down Tesla’s electricity costs to 40 cents per kilowatt-hour. The difference between that cost and the 7 cent per kilowatt-hour locked-in price is not much different from how Tesla subsidizes Supercharging for its cars.
With claims regarding the Semi out of the way, there’s an issue of space with the Roadster.
Tesla claims a range of 620 miles on a single charge, almost twice the range of Tesla’s other vehicles.
2020 Tesla Roadster
Musk himself stated the range would require a battery pack twice the size of any battery the company currently makes for automotive use, and size is something the Roadster doesn’t have.
Morsy thinks the answer for this is to stack two battery packs in the Roadster’s floor. It’s difficult, but he believes Tesla’s engineers can solve any battery management issues this arrangement may cause.
He also believes the energy density of batteries will increase enough by 2020 that the Roadster will be able to pull off the feat.
“The trend in battery density is, I think, central to any claim Tesla made about both the Roadster and the Semi,” Morsy said. “That’s totally fair. The assumptions on a pack in 2020 shouldn’t be the same ones you use today.”