As an engineering service provider, M.TEC designs technical solutions in the field of high-voltage storage or battery housings for electromobility.
High-voltage battery casing or battery housings for electromobility protect both the battery cells and the environment. The development of the housings involves complex, contradictory requirements such as "light and robust" as well as "cost-effective production and long service life". M.TEC resolves these conflicts with intelligent development systems and modern development tools.
Key challenges in development & design:
Crush-Test
Safety in vehicle operation
The so-called crush test in a press is considered the benchmark for the approval of battery cases for e-mobility in Europe and China. The housing must protect the battery cells. In the crush test, the battery housing may be loaded as an isolated component; in this case, the protective mechanisms of the entire vehicle are irrelevant.
Extreme mechanical stress
The housing must ensure the protection of the batteries under such high mechanical loads in both transverse and longitudinal directions of the vehicle. M.TEC ensures the load capacity of the battery housing by simulating the multidimensional load cases. M.TEC finds the basic structure for reducing the use of materials (economy) and weight (lightweight construction) by using computer-aided structural optimization. Thus, too much material, weight and thus high unit costs which would be a competitive disadvantage can be avoided.
Mechanical Shock Test
Multi-dimensional load case
As part of the release process on international markets, the housing must pass mechanical shock tests. Battery housings, for example, are clamped onto a slide and accelerated in different directions. One acceptance criterion is the protection of the battery cells. A further criterion is the connection to the vehicle and the basic tightness of the housing even after shock loading to exclude electrolyte leakage.
Early concept validation - structural optimization, structural analysis
In order to ensure that such tests are passed, M.TEC uses computer-aided simulations such as structural optimization and structural analysis as early as the concept creation and development process. In this way, M.TEC creates a secure basis for concept selection. By means of FE simulations during development, we ensure that the components pass the tests within the scope of qualification.
Fire Resistance Test
Fire under the vehicle
As part of the approval process, it is checked whether the battery housing can protect the battery cells for a certain period of time in the event of a fire under the vehicle, for example due to petrol. Accidents with petrol fire are possible as long as cars with combustion engines are used (hybrid vehicles, other parties involved in the accident).
In this case the duration of the fire is critical. In extreme cases the cells can overheat and be damaged (thermal runaway). The leakage of electrolyte and explosions of the Li-Ion cells must be avoided at all costs.
Heat protection on several levels
In order to guarantee protection for the required time, M.TEC uses hybrid structures, among other things. The structural strength can be guaranteed with metal components. Plastics, as poor heat conductors, are suitable to temporarily insulate the battery cells from the heat development. In addition, special technologies such as special paints or mechanical heat protection elements protect the plastic from the extreme heat and open flames for a certain period of time.
Tightness / Sealing
Protection of the battery cells and the environment
Battery housings must be constructed in such a way that on the one hand no medium (dust, water) can reach the cells from outside. On the other hand, the environment must not be polluted by escaping electrolyte. In addition, there are requirements for simple production and cost-effective, fast maintenance. This requires the design and layout of seals that reliably meet these requirements over the entire service life.
Different requirements brought in line
M.TEC considers the tolerances, materials and forces as a whole and develops assembly concepts that meet efficient production and the required service life.
Weight / lightweight construction
Light and resilient high-voltage storage
Modern battery housings must be lightweight and yet protect the cells sufficiently (high gravimetric energy density). Excessive weights reduce the range. Mechanical and thermal protection requires an appropriate use of materials. This often results in an oversized battery housing to safely meet the various requirements.
Intelligent housing concepts
M.TEC meets this contradiction with intelligent housing concepts. They include different materials, manufacturing processes from lightweight construction and an innovative computer-aided design. An essential development tool here is the structural optimization. It ensures that the maximum mechanical load capacity is achieved with the minimum use of materials.