Challenges in weight analysis in the early development phases of HV battery systems

In the early development phases of high-voltage (HV) battery systems, weight analysis is a critical aspect that significantly influences the performance, efficiency and cost of the vehicle. However, performing accurate weight estimation and analysis in these phases presents a number of technical and organizational challenges. One particular difficulty is creating a functional weight structure that reflects the evolving design.

Missing design data

In the concept and preliminary design phase, key parameters such as installation space, material selection and outer skin contours are either not defined or are only available as rough estimates. This lack of information leads to inaccurate predictions of mass distribution. Without precise cell-to-pack architecture or cooling system layouts, assumptions have to be made that can lead to significant deviations in later design phases.

Interdependence of the subsystems

HV battery systems include structural, thermal, electrical and electronic elements. Changes in one subsystem (e.g. thermal management) can affect the design and influence the mass of other subsystems. Capturing these interactions in early-stage weight models requires iterative modeling at the system level, which is often not feasible at this stage.

Difficulties in creating a functional weight breakdown

Creating a functional weight breakdown at an early stage of development is a particular challenge due to the lack of clear interfaces and definitions between the functional units. The functional weight breakdown must include weights of battery cells, housings, BMS, cabling, cooling systems and fastening elements. At an early stage, the allocation of mass to these functions is speculative, often leading to inconsistent or overlapping mass calculations. In addition, traditional Product Breakdown Structures (PBS) are not well aligned with the functional architecture, making traceability and optimization difficult.

Strategies for improvement

To meet these challenges, advanced TGM system modeling tools are integrated into the early development phase. Functional mock-ups and scalable reference architectures can help define initial mass targets. Cross-functional collaboration is essential to align assumptions and iteratively update the functional weight breakdown. In addition, the use of lightweight design principles such as functional integration and the use of modules can reduce weight uncertainty and promote early optimization.

Conclusion

Weight analysis in the early development of HV batteries is hampered by limited data, interdependencies between subsystems and difficulties in defining a functional weight breakdown. Overcoming these challenges requires integrated approaches that combine early-stage development models, digital tools and system-level thinking based on lightweighting principles.