AABC 2014 - AABTAM Symposium: Advanced Automotive Battery Technology, Application and Market - Session 4

Battery Pack Technology

Energy-storage pack design and integration present mechanical, thermal, and electrical challenges beyond those of cell chemistry. In this session, automotive-system integrators will discuss requirements, challenges, and solutions relative to the integration of energy-storage packs into light-duty vehicles, buses, commercial hybrids, and electric vehicles. This will include design, qualification verification, and field experience at the pack level.

Session Chairman:

Mr. Steven Clark is currently the Senior Manager of the Energy Storage & HV Systems Department at Chrysler Group LLC in Auburn Hills, MI. Mr. Clark is also on the Management Committee of the U.S. Advanced Battery Consortium (USABC). He joined Chrysler in 1984 and has held positions in 12 volt Powernet & Batteries, E/E Systems, Powertrain E/E Systems, Core Powertrain Controllers and the HEV team at the Hybrid Development Center in Troy, MI. Mr. Clark’s current responsibilities include: Energy Storage Systems, Battery Management Systems and High Voltage Systems development. Mr. Clark holds a BSME and an MBA from the University of Michigan in Ann Arbor, MI.
 

1. The High-Voltage Batteries of the BMW i3 and BMW i8
   Florian Schoewel, Project Manager, i3 Battery, BMW
   Abstract 

   

   With its new BMW i brand, BMW is offering sustainable and innovative solutions for individual mobility. Two revolutionary vehicle concepts with LifeDrive architecture have now entered the market within this brand: the all-electric BMW i3 and the very progressive sports-car BMW i8. The unique drivetrain architectures of both the BMW i3 and i8 offer an optimum weight distribution and the battery packs could be designed as highly integrated units with an optimized weight.

   The high voltage batteries of the BMW i products are the third generation of BMW’s HV battery systems on the road. The battery systems are produced on an ultra-modern assembly line at the BMW plant in Dingolfing. The cells are supplied by a cell manufacturer; the rest of the system is developed and assembled by BMW.

   The BMW storage systems are characterised by a very long life expectancy, safe operation as well as light-weight design which was achieved by innovative measures and architectures. For example, the battery weight per installed energy of the BMW i3 has been reduced by 45% compared to the BMW ActiveE. Furthermore, an innovative and highly efficient cooling system using refrigerant cooling optimally tempers the battery systems and improves battery performance and durability. Customers get a warranty on the batteries of eight years or 100.000 kilometres.

   Due to a new modular approach almost all elements of the electric storage systems can be used in the same or slightly modified form in future plug-in hybrid or electric vehicles of the BMW group. In our contribution we will explain given vehicle requirements and will derive the technical solutions worked out for the BMW i3 and i8 during the development process.

   The main characteristics of the batteries are

   	BMW i3	BMW i8
   Cells	96 (60 Ah)	96 (60 Ah)
   Power	147 kW	105 kW
   Energy stored	22 kWh	7.1 kWh
   Weight	233 kg	98 kg

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2. Mechanical Designs for Battery Packs
   Peter Pichler, Product Manager, MAGNA STEYR Battery systems
   Abstract 

   

   The mechanics of Li-Ion Battery packs is often underestimated in its complexity.  In fact only a robust, fully validated mechanical design including sufficient und balanced cell cooling ensures a reliable and safe system over the full lifetime.  The final serial concept of the LI-Ion battery has to be developed and chosen depending on vehicle requirements like mechanical strength, safety, service concept, cooling needs, interfaces, packaging location and costs influenced by volume.

   The presentation will discuss:

   • Requirements for Li-Ion battery packs which are relevant for the mechanical design
   • Different technologies and solutions for the housing of LI-Ion battery packs
     • AL die casting
     • Al casting
     • Deep drawing sheet steel
     • Welded construction steel
     • Plastic covers
     • Plastic housing
      
   • Comparison and discussion of the different solutions

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3. Thermal & Electrochemical Simulation of Automotive Battery Pack Systems
   Steve Hartridge, Director, Electric & Hybrid Vehicles, CD-Adapco
   Abstract 

   

   This presentation looks at the state of the art of simulation technology in the field of thermal and electrochemical modelling of battery cell, module & packs. Thermal modelling of complex three-dimensional systems can be considered a mature field and deployed to address many applications but the addition of electrochemistry to this system is a recent advance. This advance adds many considerations and layers of complexity, which an engineer needs to consider when conducting simulations. The presentation will highlight the critical aspects of such simulations and highlight their importance through examples including:

   • Creating electrochemistry models of battery cells
   • Performance modelling of cells & battery modules or packs
   • Fidelity considerations for performance simulations
   • Influence of electrical and thermal connecting components on cell performance
   • Abuse modelling
   • Cold crank simulations

   This presentation will also provide grounding on how to evaluate such results and understand their relevance to the real case to improve designs through the application of simulation technology.

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4. ARPA-E Program for Next Generation Batteries
   Ilan Gur, Program Director and Senior Commercialization Advisor, ARPA-E
   Abstract 

   

   The Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E) was created to be the "DARPA for Energy", with a focus on game-changing R&D that can reduce U.S. foreign energy dependence and emissions. ARPA-E is funding a wide range of breakthrough battery technologies to accelerate adoption of electrified vehicles, with innovations spanning from materials and cell to systems and vehicle integration. This presentation will highlight these efforts, giving a glimpse into the future of automotive battery technology.

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