Reconfigurable EV battery could extend pack life by more than 20% in modeling
Chalmers researchers modeled a reconfigurable EV battery that can bypass weak cells. In one 80 kWh, 12,000 km/year scenario, replacement was delayed by about 14 months.
A single degraded cell can limit an entire EV battery pack even when the remaining cells still work well. Researchers at Chalmers University of Technology in Sweden assessed a reconfigurable architecture that can bypass weakened cells and keep using the remaining capacity. In a modeled vehicle with an 80 kWh battery driven 12,000 km per year, battery replacement could be delayed by about 14 months.
Conventional packs use largely fixed electrical connections, so the weakest cell can constrain a whole series string. The proposed design adds electronic switches and control logic that can isolate a degraded cell or group of cells and route current through the remaining elements.
The Nature Communications study found that the most detailed and idealized configuration could extend lifetime by more than 20% for some high-voltage batteries. The benefit was strongest in electric trucks and long-range passenger EVs with many cells connected in series. The researchers stress that the figure above 20% is a theoretical upper bound because the model assumes individual control of every cell. More practical group-level switching needs less electronics but delivers a smaller gain.
There is also a cost trade-off. At current component estimates, the added electronics raise pack cost by about 9%. The researchers place an approximate break-even point near 12%; above that, a lifetime economic benefit becomes less likely. Their more robust modeled case used an added cost below roughly 7%, battery capacity above 50 kWh and annual mileage below 12,150 km. The present hardware estimate also assumes production of only about 1,000 sets, close to prototype scale.
The technology goes beyond ordinary cell-health diagnostics. It must not only detect degradation but dynamically change the battery's electrical configuration, disconnecting weak cells or groups from the active circuit.
No series-production passenger car or truck currently uses the exact architecture studied. Experimental systems and demonstrators do exist: Chalmers cites Volvo SmartCell and road testing of a prototype by a major automaker. The modeled results therefore should not be applied directly to today's production EV batteries. The work instead shows a possible way to use a pack longer and reduce the chance that a few faster-aging cells force premature replacement of the whole battery.