In this $340,000 Cadillac EV, the battery cells are hidden throughout the car
When Cadillac designed its new ultraluxury EV, the handcrafted Celestiq, the design team had to completely rethink its battery pack: a standard EV battery wouldn’t fit inside.
“We had a challenge, because due to the low roof height and the expressive proportions, there wasn’t room for a typical battery in this vehicle,” says Tony Nausieda, chief engineer of electrical propulsion systems at GM. “It would have been probably pretty straightforward to do something like an internal combustion powertrain, but that was not at all what anybody wanted to do. This was conceived to be an electric vehicle.”
They couldn’t compromise on the low lines of the car. It also had to be spacious inside—including in the back seat, because the type of person who owns a bespoke vehicle that starts at $340,000 often uses a driver. And the battery needed to be big enough to give the car at least 300 miles of range.
To tackle the challenge, they took a new approach to the layout of the battery cells. In other GM vehicles, the cells are stacked vertically in a tray. (The company calls the arrangement “toast” since it looks like slices of bread.) But for the Celestiq, the battery cells lie horizontally. And instead of having a uniform height, the battery pack varies from front to back. “It’s more of a topographical situation,” Nausieda says.
Underneath the passenger seat in the front, the stack of cells is slightly higher; under the second row footwell, the stack is very short to provide as much legroom as possible. Because there was much more room under the second-row seat cushions, the batteries are stacked higher there. Once the engineers had gotten to that point, there were still 25 miles short of what the car needed in range. So, they designed a new console in the interior, from front to back, and added 24 more battery cells in the tunnel they’d created. “That put us comfortably above that 300-mile limit,” he says.
The unusual arrangement was possible because GM’s “Ultium” battery system, created in a partnership with LG Energy Solution, was designed for flexibility, with cells, modules, and packs that can be built in different configurations. The Celestiq’s particular battery pack design is unlikely to be repeated in other models, since it’s more difficult to assemble; the luxury car is made by hand and doesn’t need to be made at scale. But it’s one example of the car company’s road map to move from a one-size-fits-all battery to developing the ideal battery for a particular car.
In this case, the designers didn’t have a choice. Typically, “your vehicle design and configuration is really somewhat bounded by the propulsion technologies that you have available to you,” says Nausieda. But with the Celestiq, the design came first and the engineers had to make the battery work. “We took a clean sheet of paper approach and made sure that we had the right battery to support this vehicle and not compromise,” he says.