20 October 2026

^{Smarter battery packs can give electric car batteries a longer life. The illustration shows a reconfigurable battery pack where all cells have their own switches, which are controlled by a battery management system (blue lines). A weak cell (dark) can be bypassed while the current (yellow) continues through the rest of the pack. Illustration created by Albert Škegro, Chalmers University of Technology, Sweden, with the help of AI.}

 

An electric vehicle (EV) battery can become less useful long before all its cells are worn out. Some deteriorate faster than others, restricting how much energy the healthier cells can deliver. Researchers in Sweden have investigated whether changing the electrical connections inside a pack could keep more of that capacity available for longer.

These reconfigurable battery packs use switches to change electrical connections as cells age. Their appeal lies in making better use of components that manufacturers have already paid to produce.

Chalmers University of Technology highlighted the findings on 8 October. Published in Nature Communications in July, the study examines an existing concept known as dynamic reconfiguration, assessing where it could deliver worthwhile improvements in battery lifetime and cost. 

 

Why weak cells can limit EV battery life

 

An EV battery contains many individual electrochemical cells, connected to provide the voltage and energy the vehicle needs. Although manufactured to closely controlled specifications, these cells begin life with small differences in capacity and electrical resistance.

Those differences can grow. Cells experience varying temperatures within the pack, and their performance changes with use and age.

A separate study published in Nature Energy in August, involving Chalmers researchers and industry collaborators, examined real-world vehicle data to quantify how cell inconsistency affects battery performance. It identified consequences for usable energy, power and lifetime.

This creates a problem in a conventional series connection, where the same current passes through successive cells. A weaker cell may reach its safe operating limit before its neighbours. Continuing to draw energy could push that cell too far, so the pack’s operation must respect its limits even when other cells retain usable capacity.

Battery management systems already monitor cells and can balance their charge. Reconfiguration adds another capability: changing which cells participate in the electrical circuit.

 

How reconfigurable battery packs work

 

In a reconfigurable pack, controlled switches can isolate a selected cell while providing a bypass around it. Current can therefore continue through the remaining cells without leaving the circuit broken.

The effect is to preserve access to useful capacity elsewhere in the pack. It does not repair the bypassed cell, restore energy already lost through ageing or automatically increase the vehicle’s original range.

This is a system-level approach to a problem that develops unevenly across its components. Rather than requiring every cell to remain closely matched throughout its working life, the electrical architecture can adapt as differences emerge.

The team used experimentally validated cell models to explore how manufacturing variation, temperature, usage, voltage and battery chemistry affect the potential benefit. Its results describe an idealised control strategy, rather than a controller demonstrated over a vehicle’s working life.

Potential lifetime extension exceeded 20% in certain high-voltage applications. However, the study defines the conventional pack’s end of life as the point when its first cell falls to 80% of nominal capacity, and compares this with idealised management of the reconfigurable pack’s cells. This is a modelling threshold, not a requirement to replace a real battery at 80% capacity.

The findings therefore indicate the potential to delay a defined performance limit. They do not establish that current EVs could gain 20% more years on the road.

 

Why high-voltage EVs could benefit more

 

Higher-voltage designs generally require more cells connected in series. That creates more opportunities for a cell to age faster than its neighbours and constrain the group, increasing the potential value of selectively bypassing it.

The researchers therefore identify high-voltage applications, including long-range passenger vehicles and electric trucks, as particularly interesting. Battery chemistry and differences in operating conditions also influence the result.

However, the most flexible architecture in the analysis assumes individual control over every cell. It represents an upper bound on achievable performance.

Manufacturers could instead control groups of cells, reducing the hardware and packaging burden. The compromise is less precision: a system switching an entire group cannot isolate one deteriorating cell while retaining all its healthier neighbours.

The commercial design may consequently deliver less than the modelled maximum while offering a more practical balance of cost and benefit.

 

Do longer-lasting EV batteries justify the extra cost?

 

Additional electronics raise initial expenditure and introduce electrical losses. Chalmers estimates an approximately 9% pack-cost premium using automotive-grade components priced at prototype-scale volumes of 1,000 units. That estimate is separate from the lifetime model’s maximum benefit.

The economic analysis weighs these costs against deferred replacement, maintenance assumptions and residual battery value. In its representative case, an 80 kilowatt-hour lithium iron phosphate battery, driven 12,000 kilometres annually over an assumed 18.8-year vehicle life, delayed modelled replacement by roughly a year—around 14 months in Chalmers’ announcement.

In the baseline economic scenario, the reconfigurable pack reached cost parity with the conventional design after approximately 9.1 years. By the assumed end of the vehicle’s life, the model calculated a saving of around €941, accounting for the timing of future costs and residual value.

The result is a projected saving in battery-related lifetime costs. It is sensitive to assumptions about replacement, maintenance and what a used battery will be worth; it does not predict a reduction in a car’s purchase price.

Other scenarios produced larger savings, while unfavourable conditions left the extra investment unrecovered. A battery that lasts longer is therefore not automatically the cheaper option.

Ownership duration also affects how such benefits are understood. If a conventional battery already serves until the vehicle is retired, postponing a hypothetical replacement has less practical relevance. The value of flexibility must be assessed against what would otherwise happen in that particular application.

 

From battery modelling to road testing

 

Experimental automotive systems already exist, but Chalmers says long-term studies following this architecture throughout a vehicle’s lifetime are still lacking.

Turning the modelling into a production design will require dependable switching, effective control and acceptable electrical losses. Manufacturers must establish how much benefit remains when cost, space and reliability constrain the architecture.

There may also be opportunities after the vehicle: managing unevenly aged cells could help packs remain useful in stationary storage, subject to appropriate assessment and integration.

A battery that can work around deteriorating cells could keep useful materials on the road for longer. Its route into everyday vehicles depends on delivering that flexibility at a cost, and with a reliability record, that makes it worth building into a car.