Chalmers Researchers Model Reconfigurable EV Battery Packs That Bypass Weak Cells
Study published in Nature Communications finds architecture could extend battery life by over 20% in high-voltage vehicles while raising pack cost by approximately nine percent.
Researchers at Chalmers University of Technology in Sweden have assessed how much reconfigurable battery packs could extend EV battery life and reduce lifetime cost. The study, published in Nature Communications, was carried out with PHINIA and Scania.
What Happened
Battery packs in EVs consist of many interconnected cells that do not age in the same way. In a conventional pack, the weakest cell can therefore set the limit for the entire pack. Albert Škegro, a doctoral student at Chalmers and the study’s first author, explains the problem by picturing the cells connected by a rope while they all try to move forward. "Since they are bound to each other, everyone has to keep the same pace as the slowest cell and stop when that cell stops," said Škegro. "With the solution in our study, the battery can instead bypass the cell that is causing problems and continue forward." In a reconfigurable pack, switches and control systems can change the connections between the cells.
Why It Matters
The researchers say that in their models, controlling each cell separately could extend battery life by over 20% in some high-voltage vehicles, such as electric trucks and long-range cars. In practice, groups of cells are more likely to be controlled together, so that figure is a theoretical upper limit. In one example, the researchers modeled a typical 80 kWh battery in a car driven 12,000 km per year and assumed a conventional pack would be replaced after 10 years. In the model, the reconfigurable pack reached that replacement point after about 11 years, roughly 14 months later. It also had a higher residual value because it had degraded less. The technology is not yet available in series-produced vehicles but has been tested in research and industrial prototypes. Reconfigurable packs require additional electronics, which raise their upfront cost. "The results show that the architecture can already be cost-effective under a wide range of real-world usage conditions," said Changfu Zou, Professor at the Department of Electrical Engineering at Chalmers. "Based on a component-level analysis using automotive-grade hardware, the additional hardware would increase the total pack cost by approximately nine percent."
The Bottom Line
Reconfigurable battery packs offer a modeled pathway to extend EV battery life and improve residual value by bypassing weak cells, with a potential life extension of over 20% in some high-voltage applications. While the technology adds approximately nine percent to the pack cost and remains in the prototype phase, researchers assert it could be cost-effective over the vehicle's lifetime.
