Is Tesla moving on from the skateboard battery design?
Tesla’s skateboard battery pack is one of the company’s most important innovations. When it was introduced in Model S, it was nothing less than a revolution in automotive design. Franz von Holzhausen, who joined Tesla as Chief Designer in August 2008, was one of the masterminds of the concept, and he seems to have coined the term itself. “The architecture of Model S is really similar to a skateboard,” he told Bloomberg in 2011. “The floor of the vehicle is the battery pack, and the motor is between the rear wheels. Everything above that is the opportunity space.”
Above: A look back at the early, original 'skateboard' design of the Tesla Model S (Source: Tesla)
The skateboard architecture that Tesla introduced with Model S has so many advantages that just about every native EV (that is, not a conversion of a gas vehicle) designed since then has used it. Now that the traditional auto industry (including GM, whose new Ultium battery platform looks very familiar) has embraced the skateboard, is it time for Tesla to abandon it?
For Model Y, Tesla adopted a new manufacturing technique—using a single huge casting for the vehicle’s rear underbody—which reduced the number of parts needed. Now it appears that this concept has led to an even more transformative idea: making the battery pack a structural part of the chassis.
The concept of structural battery packs was announced at Battery Day, and Elon Musk offered a few more details later on Twitter. “Battery pack will be a bonded structure with cells providing shear transfer between steel upper & lower face sheets, eliminating most of the center body parts while providing better torsional rigidity & improved polar moment or inertia,” tweeted Elon. “This is a major breakthrough.”
Such a breakthrough, in fact, that it’s worth ditching Tesla’s innovative and iconic skateboard. As Teslarati reports, Musk confirmed that the skateboard is on its way out during the recent Q3 earnings call. In response to a question from an analyst, he said that, although the transition to structural battery packs will take years, the skateboard will eventually become “obsolete.”
Above: More insight into Tesla's new structural pack (Source: Tesla)
“It’s not like existing cars stop having value,” said Musk. “It’s just that if you have a structural pack, where the pack is contributing structural value to the car because of...the composite honeycomb effect of share transfer between upper and lower plate, then anything that doesn’t do that is going to have to have duplicate hardware. It’s going to weigh more. It’s going to cost more. And then the same goes for the front and rear castings.”
Musk drew a comparison with the evolution of aircraft. Early flying machines had separate fuel tanks, but designers eventually figured out that it made more sense to store fuel inside an aircraft’s wings.
“The early rockets and aircraft, they had a separate aeroshell from the propellant tanks or fuel tanks, and then they realized that doesn’t make sense,” said Musk. “You’ve got to integrate—you’ve got to have your fuel tank in wing shape. You’ve got to have your propellant tanks in the shape of the body of the rocket, for example. You don’t want to put a box on a box.”
The new structural battery design, along with the new 4680 cells, will first appear in Model Ys produced at the new Gigafactory Berlin next year. “Berlin will use 4680 cell with structural battery pack and front & rear single-piece castings. Also, a new paint system.”
A couple of years later, these innovations will make their way to Tesla’s other production lines. “Lot of new technology will happen in Berlin, which means significant production risk,” tweeted Musk. “Fremont & Shanghai will transition in ~2 years when new tech is proven.”