Electric vehicle batteries must meet several demanding requirements at once. They need to deliver high electrical performance, control heat, withstand crashes, and remain affordable. However, these goals often create design conflicts. A battery pack may perform well during normal operation but remain difficult to inspect or repair after damage. In addition, manufacturers use different pack architectures, joining methods, cooling systems, and service procedures.
This lack of common design principles creates challenges throughout the battery life cycle. Emergency teams may struggle to assess damaged packs after collisions. Workshops may lack safe access to internal components. Recycling companies may also face complex disassembly processes.
Researchers at Graz University of Technology, or TU Graz, addressed these issues through the E-Track project. The team worked with the University of Graz and industrial partners to develop design guidelines for safer, more repairable, and more sustainable traction batteries.
The project focused mainly on batteries for electric two-wheelers. Nevertheless, its methods and simulation approaches could also support electric cars and commercial vehicles.
E-Track targets the full battery life cycle
The research team examined battery design from manufacturing through end-of-life treatment. This approach went beyond improving performance during vehicle operation.
A traction battery must support several stages:
- Manufacturing and initial assembly.
- Operation under changing electrical and thermal loads.
- Inspection after mechanical damage.
- Repair and component replacement.
- Second-life reuse.
- Material recovery and recycling.
Each stage places different demands on the battery structure. For example, manufacturers often favor adhesive bonding because it can simplify production and improve sealing. However, adhesives may make later disassembly more difficult.
The researchers therefore evaluated whether alternative construction methods could balance safety, cost, serviceability, and environmental performance. Their findings indicate that design decisions made during development strongly influence the battery’s later value.
This principle is important because a battery does not automatically become waste after one damaged component fails. If technicians can safely identify healthy cells, they may reuse those cells in another battery or stationary energy system.
Three battery architectures under review
E-Track compared a conventional battery design with two alternative concepts. The conventional design represented a common industry approach involving an adhesive-sealed housing and thermal interface materials.
Adhesive-based construction can provide several production benefits. It may reduce the number of mechanical fasteners and support compact pack integration.
However, this approach can create major repair limitations. When technicians must remove bonded covers or thermal materials, the process may damage components or require extensive labor. As a result, a localized fault can lead to the replacement of the complete pack.
Replaceable covers and thermal pads
One alternative used a housing with a replaceable cover. Thermal pads transferred heat from the cells while allowing technicians to open the enclosure more easily. This design changes the service process in several ways. Technicians can access internal modules without destroying the housing. They can also replace selected components instead of discarding the entire pack.
The approach may support faster inspections after accidents. It could also reduce the amount of structural material that becomes waste during repair. However, a removable cover must still provide adequate mechanical protection. It must resist vibration, impacts, moisture, and contamination throughout the vehicle’s operating life.
Liquid cooling with an insulated fluid
The second alternative used liquid cooling and a screwed enclosure. An electrically insulating oil carried heat away from the cells while reducing the risk of electrical short circuits within the cooling medium.
The housing used a seal and mechanical fasteners rather than permanent adhesive bonding. This arrangement supported easier opening and allowed individual cells to be replaced.
Liquid cooling can also provide more consistent temperature control across the battery. Better thermal uniformity may reduce differences in cell aging and improve long-term pack performance.
At the same time, this architecture introduces additional engineering requirements. Designers must manage fluid compatibility, sealing reliability, service procedures, leak detection, and fluid recovery.
Battery cells drive cost and sustainability
The E-Track analysis identified the cells as the most important battery components. They represent approximately 75% of the battery’s total mass, according to TU Graz.
This high material share gives cell recovery a major influence on environmental performance. If a damaged pack allows technicians to reuse only a small number of healthy cells, the design may still deliver significant benefits.
The project’s life-cycle assessment found that repair-friendly designs become worthwhile when at least 8% of the cells can be reused. This threshold demonstrates why pack architecture matters.
A conventional pack may force manufacturers to replace every cell after a localized failure. By contrast, a modular and accessible pack could preserve healthy cells and reduce demand for new materials.
The benefits also extend beyond reuse. Easier disassembly can improve the separation of metals, polymers, cooling components, electronics, and other materials.
Diagnosis can prevent delayed battery fires
Mechanical accessibility alone cannot make a battery safe. Service teams also need reliable methods to determine whether internal damage remains after an accident.
E-Track therefore examined diagnostic methods based on electrochemical impedance spectroscopy. This technique evaluates how a battery responds to electrical signals across different frequencies.
The resulting electrical response can reveal changes inside the cells. These changes may indicate degradation, internal defects, or damage that standard visual inspections cannot identify.
The team combined impedance-based diagnosis with multiphysics simulations. These simulations model interactions between electrical, thermal, and mechanical conditions. Together, the methods can help detect internal faults such as micro-short circuits. Such faults may remain hidden for a period before triggering a dangerous thermal event.
Early detection matters because a damaged battery may appear stable immediately after a crash. Internal defects can later generate heat, accelerate degradation, and increase fire risk.
How the diagnostic process could help
A future inspection process could follow several stages:
- Technicians isolate the damaged battery from the vehicle.
- Diagnostic equipment measures the electrical response of individual cells.
- Simulation models compare results with expected operating behavior.
- The system identifies cells that require removal or additional testing.
- Technicians separate healthy, damaged, and uncertain components.
This process would not eliminate the need for trained personnel. Instead, it could provide more evidence for safety decisions and reduce unnecessary pack disposal.
Repairability supports circular battery systems
Repairable batteries can create value at several points in the circular economy. First, they may extend the useful life of the original vehicle pack.
Second, recovered cells can support second-life applications. These applications may include stationary storage, backup power, and low-demand energy systems.
Third, batteries that no longer support reuse can enter recycling with less contamination and fewer mixed materials. Simplified disassembly can help recyclers process materials more efficiently.
The European Union’s Battery Regulation also places greater emphasis on battery sustainability, safety, collection, recycling, and material recovery. The legislation includes requirements related to electric vehicle batteries and states that these batteries should be removable and replaceable by independent professionals.
E-Track does not simply respond to regulatory requirements. Its design principles could help manufacturers prepare for a market where repairability and traceability become more important.
The strongest results may come from combining several measures:
- Accessible battery housings.
- Replaceable thermal interfaces.
- Modular electrical connections.
- Cell-level diagnostics.
- Standardized service procedures.
- Clear labeling for emergency responders.
- Designated pathways for reuse and recycling.
Guidelines could support wider vehicle classes
The research focused on electric two-wheelers because their battery systems offer a useful test environment. These packs can present strict constraints involving size, weight, cost, vibration, and crash protection.
Despite this focus, TU Graz states that the project’s methods can transfer to larger vehicles. Electric cars, vans, trucks, and buses face similar challenges, although their packs require different structural and thermal solutions.
For passenger cars, battery integration often involves the vehicle floor and crash structure. Therefore, designers must balance repair access with stiffness and occupant protection.
Commercial vehicles create additional demands because they operate for longer periods and may experience higher energy throughput. Their battery systems also carry significant economic value, making repair and uptime especially important.
The same diagnostic concepts could support fleet maintenance. Operators could monitor battery health, identify abnormal behavior, and plan component replacement before a serious failure occurs.
Standardization remains the next challenge
E-Track’s findings could support future industrial standards and regulatory frameworks. Yet the transition from research guidelines to production systems will require further validation.
Manufacturers must test repairable designs under real-world conditions. These tests should cover crash loads, vibration, water ingress, corrosion, thermal cycling, and long-term aging.
Service procedures also require careful definition. A battery that appears easy to open may still create hazards if technicians cannot safely disconnect high-voltage circuits or handle damaged cells.
Standardization could improve emergency response as well. Common pack layouts, hazard labels, and access points would help rescue teams assess unfamiliar batteries more quickly.
Industry cooperation will therefore remain essential. TU Graz reports that industrial stakeholders have already shown interest in follow-up projects involving safety-status diagnosis and multiphysics simulation models.
What E-Track means for EV manufacturers
The project offers a practical message for battery developers. Pack design should account for repair, reuse, and recycling from the beginning.
Manufacturers can no longer evaluate batteries only through energy density, range, charging speed, and production cost. They must also consider how technicians will inspect and disassemble the pack years later.
The most effective design may not be the one with the fewest parts. Instead, it may be the system that delivers acceptable performance while preserving access to valuable components.
E-Track also highlights the importance of cell-level information. Without accurate diagnostics, manufacturers cannot confidently decide whether cells remain safe for further use.
A repairable battery could reduce material demand, lower ownership costs, and limit waste. It could also make electric mobility more resilient as battery volumes increase.
Key takeaways
- TU Graz led E-Track with the University of Graz and industry partners.
- The project developed guidelines for safer and more sustainable traction batteries.
- Researchers compared adhesive, replaceable-cover, and liquid-cooled designs.
- Battery cells represent about 75% of total pack mass.
- Reusing at least 8% of the cells can justify repair-friendly designs.
- Electrochemical impedance spectroscopy can support internal damage detection.
- Multiphysics models can help identify hidden electrical and thermal risks.
- The methods developed for electric two-wheelers could support cars and trucks.
- Easier disassembly can improve repair, second-life use, and recycling.
- Follow-up projects may advance battery diagnostics and safety assessments.
E-Track presents battery repairability as a core engineering objective rather than an afterthought. Its findings suggest that safer structures, better diagnostics, and simpler disassembly can reinforce one another.
For the EV industry, this approach could reduce waste without compromising vehicle safety. It may also help establish the technical foundation for more consistent battery standards.
Sources: TU Graz
