AABC Europe 2015 - AABTAM Symposium: Advanced Automotive Battery Technology, Application & Market - Session 2

Energy Storage for Low-Voltage Hybrids

Session Chairman:

Dr. Karden is Technical Expert for Battery & Energy Storage Technology at Ford's Corporate Research and Advanced Engineering Centre in Aachen, Germany. Since he joined Ford, he was responsible for numerous projects in the fields of powertrain electrification, battery modeling and monitoring, and storage technology assessment, with a main focus on micro-hybridization in 14V systems.

1. 14V Micro-Hybrid Systems Update
   Eckhard Karden, Technical Expert, Ford Research Aachen
   

   Micro-hybrid vehicles have gained significant market share in Europe and Japan during the present decade, and are forecasted to grow further in these and many other markets. When applied in large volumes, they provide a significant contribution to carmakers’ roadmaps for reduction of fleet-average fuel consumption and CO2 emissions. At the same time, new electric functionalities are entering the mass market. As a consequence, performance and durability requirements to low-volt automotive energy storage systems are raising, while cost pressure remains dominant. The session chairman’s introduction will provide an overview of key requirements, emerging preferred technical solutions, and current challenges to each of the technologies being considered.
2. Dynamic Charge Acceptance and Water Consumption of Lead-Acid Batteries Optimized for µ-Hybrid Application
   Olaf Sielemann, Director Transportation R&D Europe, Exide Europe
   

   EXIDE Technologies is working since 2006 on optimization of lead acid for µ-Hybrid application. Several design approaches have been evaluated for flooded and valve regulated designs. One key element are carbon additives to reduce NAM sulfation and the optimization of depolarization of the negative electrode. This is enhancing the dynamic charge acceptance and cycle life of the battery. The drawback is the potential impact on water consumption.

   The presentations will discuss the following highlights:

   • Advantages of carbon additive in terms of dynamic charges acceptance and cycle life for EFB and AGM batteries.
   • Water consumption effects and test scenarios. Comparisons of lab results versus real life tests.
   • How to balance battery design in terms of dynamic charge acceptance, cycle life and water consumption.
   • Outlook for further evolutions on EFB and AGM batteries for µ-Hybrid application.
3. Advanced Lead-Acid Battery in a 48V Kia Mild-Hybrid System
   Ulf Stenzel, Lead Engineer New Battery Technologies – Hybrid & Electric Powertrain Systems, AVL Schrick GmbH
   

   The Diesel engine plays an important role in achieving current and future CO₂ fleet targets. Electrification of Diesel drivetrains can further optimize fuel consumption and simultaneously offer a sustainable product to the market.

   Starting with a generic roadmap towards an optimized Mild Hybrid concept and its theoretical potentials in CO₂ reduction and performance enhancement the applicability of advanced Lead-Acid battery technology in a 48V Mild Hybrid Diesel powertrain system will be discussed. As an independent company for the development of powertrain systems AVL will give an objective view on the electrical performance of advanced Lead-Acid battery technology in the 48V Mild Hybrid Diesel powertrain architecture. 48V eStorage electrical requirements will be presented and performance differences between state-of-the-art battery technologies will be discussed in an application-specific gap analysis. The presentation concludes with a summary of achieved results and the challenges with advanced Lead-Acid battery technology in the 48V application.

4. Analysis of Optimal 12V Li-Ion Battery Requirements for the EU Market by Vehicle Segment
   Lawrence Alger, Principal Engineer, Denso
   

   Stringent future EU CO₂ legislation can no longer be met through improvements in engine efficiency. As a result, it will be necessary to expand “no fuel” operation beyond simple Stop & Start systems in wide-spread use today (engine stop when vehicle stop).
   Expanding “no fuel” operation beyond vehicle stop phases requires a high performance secondary power source to store the energy recuperated during deceleration, which can then be used to supply all system loads during ISS coasting (engine stop when gently decelerating).

   The power and energy requirements of the secondary power source are heavily influenced by the “no fuel” operation strategy and the vehicle class, making a “one size fits all” solution very challenging. However, to maintain the order of scale required to limit both costs and development lead time, it is essential to keep the number of variations to a minimum.

   Therefore, to better understand future EU market needs an evaluation of secondary power source requirements for each application was undertaken.

   This presentation explores the issues described above and covers the following topics:

   • Background / motivation for adopting a secondary power source
   • Analysis of various “no fuel” operating strategies / topologies
   • Issues to be overcome
   • Evaluation of secondary power source requirements
   • Summary
5. Low-Voltage Dual Battery Systems Utilizing LTO Anodes
   Koji Ishiwa, Senior Manager, Supercharge Battery Engineering Department, Automotive Systems Division, Social Infrastructure Systems Company, Toshiba Corporation
   

   The low-voltage hybrid vehicle, especially 12V advanced Start & Stop (S&S) system is strongly focused because the fuel consumption is effectively improved by the recuperative energy to be stored in the secondary battery. Lithium ion battery with Lithium Titanate (LTO) as the anode is recognized to be the best matched with these low-voltage hybrid systems because of longer life, higher recuperation capability, higher safety and voltage harmonization with lead-acid battery. Toshiba is only manufacturer which can mass-produces the LTO-basis battery cells, SCiB™, with high-quality, and has been providing the power type of 3Ah cell to the advanced S&S system from 2012 which automobile sales installed in lithium-ion battery is remarkably high compared to EV or HEV. Further improvements are expected by adding new functions of coasting, re-cranking and motor-assist.

   In this presentation, the new product lineup and the performance of SCiB™ will be introduced for the future vehicle system as follows:

   • Tuning of cathode materials to match with the voltage requirement of 12V and 14V.
   • Increase of cell capacity and size to provide the more power
   • Safety requirement
6. LTO and LFP Chemistries for 14V Systems
   Christoph Fehrenbacher, Director of Engineering Europe, A123 Systems
   

   CO₂ emission reduction and fleet average fuel economy improvement are long-term global targets. Micro hybrids offer a favorable balance between incremental cost and improvement of average fleet consumption and are therefore a key technology in the vehicle manufactures’ portfolio to meet future regulations. It is expected that micro hybrids will capture a high market share as they are becoming standard equipment for mainstream powertrains. Micro hybridization drives the need for more robust low voltage battery systems, largely fulfilled by the properties of lithium-ion technology.

   • Lithium-ion technology alternatives for micro hybrids
     • Single battery system
     • Dual battery system
      
   • Battery requirements
     • Micro-hybrids (12V)
     • 48V hybrid
      
   • Comparison of lithium-ion chemistry fit
   • Cell design considerations