We have been manufacturing battery trays for well-known customers for almost a decade – and therefore have proven experience. But we’re not satisfied with that. We invest continuously in expanding our expertise and are involved in research and pre-development projects because we want to know today what challenges our customers will face tomorrow. And we want to offer them optimum solutions, for example by showing them what options are available for adapting battery trays to changing conditions.
Battery trays are currently mainly constructed from extruded aluminum profiles, which results in numerous joints. Swivel bending of the sheet metal battery housing and local reinforcement of weak areas opens up new, efficient possibilities.
New approaches for the necessary crash reinforcements are also possible – for example single- or multi-layer press-hardened sheet steel solutions, e.g. as a cost-effective alternative to roll-formed crash profiles.
The crash protection of a battery trays depends on the crash behavior of the overall vehicle. To analyze the interrelationships in detail, novel battery carrier designs were crashed virtually and optimized in the overall system of the BENTELER Electric Drive System (BEDS).
Other loads, such as the twisting of the battery carrier while driving, were also evaluated and the design optimized.
Aluminum extrusions play an important role in the field of battery trays. What is often not considered is that sheet metal solutions can be an attractive alternative. Steel has advantages in terms of cost and carbon footprint, but also in terms of fire protection in certain cases. To avoid painting such large components, stainless steel solutions are an interesting alternative.
We are prepared for all options – whether it’s aluminum extrusion or sheet, or steel or stainless steel. We’ve considered and tested all solutions.
A battery carrier constructed from extruded profiles requires many joints, which must be sealed. Deep-drawn solutions reduce the number of joints but require large dies and presses. Why not produce a component made from a simple sheet in a swivel bending process that only requires a few joints to be made? We’ve already successfully tested this together with TRUMPF SE + Co. KG.
A battery tray is built using a large number of different joining technologies that must reliably perform different tasks. In the case of bonded joints, for example, the focus is on strength or sealing requirements. The perfect choice of adhesive and appropriate surface pretreatment is crucial: whether it’s steel or aluminum, what’s decisive is whether it will be painted or not. We know – we’ve already tested it.
New forming and joining processes for battery trays that are not yet in series production have yet to prove their suitability in extensive tests. For example, can a laser welded or a resistance spot-welded, and subsequently sealed, folded box meet the dynamic requirements so that not only the required fatigue strength are achieved but also the seal is maintained? Our scaled tests show that it is possible!
In our research, we have also analyzed closed hot-formed profiles and solutions made from various metals. Here, questions such as corrosion protection in cavities or contact corrosion issues are particularly important. However, questions about alternative paint processes for steel applications are also relevant, since some of the components are very large. These could cause problems in many cathodic dip painting facilities or make corresponding new investments very expensive. Together with the University of Paderborn, we have therefore systematically analyzed possible alternatives.
Electric vehicle batteries generate heat during charging and operation. The charging speed, the performance as well as the service life depend decisively on the correct temperature control of the batteries. Here, too, we have looked at and tested alternatives to the technologies previously used to manufacture temperature control plates. Our current variant has the potential for reducing costs, investment and, above all, considerable CO2 emissions.
Batteries currently used in electric vehicles require special protection, as they could ignite if damaged. In such a case, it’s important that the occupants can stop and exit the vehicle safely. In addition to aluminum, which is commonly used, steel and stainless steel, which have a significantly higher melting points, could become more important in the future. We have already intensively investigated solutions made from both materials.
"Concept development for a steel battery housing with special consideration of the joining technology and corrosion protection".
The aim of this group project with the participation of industrial partners is to exploit the advantages of ultrahigh-strength steels in the conceptual design of battery housings while specifically addressing the limitations on the freedom of design. The conceptual design also takes special account of the requirements and solutions resulting from the overall project with regard to corrosion protection, leak tightness and joining technology. In addition, a complete life cycle analysis will be carried out in this project to also evaluate the environmental impact holistically compared to a reference model.
The group project is funded by the BMWK within the framework of the IGF call for proposals "Leading Technologies for the Energy Turnaround" and supervised by the Forschungsvereinigung Stahlanwendung e.V. (FOSTA). The Forschungsvereinigung Automobiltechnik (FAT) and the Forschungsgesellschaft für Pigmente und Lacke e. V. (FPL) support the research project as cooperating research associations.
"ULSAS E-VAN: Ultra-light body structure for a light electric commercial vehicle".
BENTELER, together with its partners Ford-Werke GmbH, Altair Engineering GmbH, Franken Guss GmbH + Co. KG, C-TEC GmbH, MORPHOTEC, voxeljet AG and RWTH Aachen University (IKA & SLA), is developing lightweight body structures and a modular battery tray system of electrically powered light commercial vehicles. Cost-efficient lightweight construction is required here in this cost-sensitive segment. In the structural area, frame-stringer construction technology, proven in aircraft construction, is used. This adapted for automotive use with correspondingly high quantities. The focus at BENTELER is on the development of a modular and size-scalable battery tray.
This research project is funded by the BMWK as part of the "Lightweight Construction" technology transfer program.