Performance

FEV Battery Benchmarking

4. August 2020 | Featured Article

Benchmarking offers unique opportunities for detailed insights into new technologies. Performance data, construction details, materials used, manufacturing processes utilized, and system functions can be analyzed using a detailed benchmark study. Vehicle and system tests provide crucial measurement data that provides information on the performance of new products. The dismantling of entire vehicles or individual technical systems shows the product structure and enables us to recognize necessary assembly processes.

Do you like to always to be a step ahead? The findings from specific benchmark programs help you to be that decisive step ahead in order to generate design and product ideas in interdisciplinary expert workshops. A neutral assessment of your own developments by a partner such as FEV provides you with that important external perspective.

In addition to the specification of technical product characteristics, the optimization of the cost structure is essential to developing competitive advantages. What is referred to as a “should-cost” calculation is carried out on the basis of a detailed analysis of the dismantled components. The should-cost analysis shows what the relevant product should cost with its current design and under the assumptions made. The results of the cost analysis provide insight into competitive costs and form the basis for defining target costs. As part of structured value analysis and cost reduction workshops, interesting cost reduction measures are determined that can be used to improve your own products.

For electric vehicles, the high-voltage battery represents a major cost item. Accordingly, a main focal point for the cost optimization of electric vehicles is the optimization of the battery. The benchmarking of battery systems newly launched on the market is an important part of the strategic development of the battery systems of the future.

In addition to the battery costs, technical benchmarking provides crucial insights regarding various performance aspects. An advance in energy density, and thus in range, represents a significant, unique selling point. Information on cell chemistry, battery management systems, and thermal management is important data that can be used for the further development of your own systems.

What do you need?

  • More in-depth insight into the latest technologies?
  • Understand the construction and functions in detail?
  • Important measurement data for performance parameters?
  • Understand the cost structure of your competition?

All batteries are not equal

In the automotive field, there are significant differences between different battery applications. Generally speaking, there are three battery types (Figure 1).

Figure 1: Main requirements per battery type (Status 2020)

The battery in a Mild Hybrid Electric Vehicle (MHEV) serves to power a 48 V onboard network and provides power capacities of up to 30 kW. The batteries of a Hybrid Electric Vehicle (HEV) offer power capacities of up to 200 kW and the batteries for Plug-in Hybrid Electric Vehicles (PHEV) provide, beyond that, an increased electric range and the option of external charging. For this battery type, energy and power density also play an important role. In contrast, traction batteries with high energy density are used for purely electric powertrains. Here, different cell types are to be used depending on the applications. In addition to the electric characteristics, these are also differentiated by design and cell chemistry. There are cylindrical, prismatic and “pouch” cells, as well as different cell chemistries, from the currently popular nickel manganese cobalt oxide (NMC) in various allocations, lithium titanate oxide (LTO), or lithium iron phosphate (LFP). Each technology has advantages and disadvantages with regard to power data, construction details, materials used, manufacturing processes utilized, total costs of ownership (TCO), and longevity.

Figure 2: specific gravimetric energy density at the pack level

If you now compare the respective gravimetric or volumetric energy density at the system level, larger differences appear due to cell selection, as well as module and system design. For electric vehicles, this consideration is an important distinguishing feature, since the energy density directly results in the range available to the client (Figure 3). For instance, if you compare newer BEVs, such as the Tesla Model 3 Long Range (2018) and the Hyundai Kona Electric 150 kW (2018), to each other, the differences are clear. The Tesla Model 3 Long Range has an energy capacity of 78 kWh with a battery weight amounting to 457 kg. By way of comparison, the Hyundai Kona Electric 150 kW has an energy capacity of 64 kWh with a battery weight of 452 kg. In the benchmarking comparison at the cell, module, and system level, the differences can now be assigned to technical measures. In this context, development teams can be provided with valuable information for future battery technologies.

In addition to the right cell selection and the construction details at the module and system level, thermal management plays an important role. There are different cooling concepts, from air cooling to indirect cooling using cooling sheets or cooling plates and water glycol, cooling via coolants, and direct cooling with dielectric fluids or the cells themselves (immersion cooling).

Costs

The high-voltage traction battery represents up to 50 percent of the total cost of ownership for battery electric passenger cars. It is thus fundamentally necessary to build a deeper understanding of the battery’s cost structure. The battery cells represent the main share of battery costs. In the example shown (Figure 3), the battery cells represent 64 percent of the total battery costs.

Modern battery electric passenger cars typically use lithium ion batteries with NMC (nickel manganese cobalt) cathode material. In particular, expensive material components, such as cobalt, drive the cell costs. One approach to optimizing battery cell costs accordingly consists in reducing the cobalt quantity. Figure 5 shows how, from a previously common uniform distribution (NMC-111), materials richer in nickel are developed (NMC-622, NMC-811, NMC-911). Using this type of optimization of the material composition, the cathode material costs can be reduced by over 40 percent. Further efforts in battery cell development aim to increase power density. A higher power density also means a cost reduction for the same battery range.

Figure 3: Design and cost structure of an exemplary BEV battery

Further cost drivers for the high-voltage traction battery are the module and battery casing components, thermal management, and the battery management system (BMS). After exceedingly complex constructions in the early battery generations, the benchmarking of the new battery generations now enables us to recognize clear approaches in terms of modularity and module structures. The goal is the achievement of scale effects and the simplification of the assembly processes.

Figure 4: Development of NMC cathode materials

In the end, the indicated approaches to cost reduction lead to further decreases in battery costs, and thus to an increase in the attractiveness of electric vehicles. While we are still seeing average battery pack costs for fully electric passenger cars amounting to approx. 180 EUR/kWh today, this value will decrease by half, to under 100 EUR/kWh by 2030. A battery with a capacity of 70 kWh will then cost less than 7,000 EUR instead of 12,600 EUR (Figure 5).

Figure 5: Battery cost evolution (average values) – Status as of 2019

Global FEV benchmarking

As a globally positioned development service provider with over 40 locations worldwide and many development centers, FEV offers extensive benchmarking services for their global clients. Dedicated benchmarking locations have been established in four core regions (Europe, USA, China, and India). Thus, local framework conditions and data can be taken into consideration, and global programmes can be run in parallel.

FEV has been conducting detailed benchmarking studies for more than 25 years. FEV uniquely combines in-depth technical expertise and cost engineering knowledge with strategic management consulting methods. The range of service provision includes extensive technical benchmarking, tear-down studies, cost benchmarking, and a benchmark academy; we also have access to extensive benchmark databases.

In addition to typical vehicle and system dismantling studies with professional photographic and video documentation, FEV engineers analyze the construction details, the functions, the materials, and the manufacturing processes. In order to carry out detailed performance and function tests, FEV has an extensive range of test systems: various on-road driving cycles, test tracks, vehicle test benches, and different system test benches – e.g. for combustion engines, turbochargers, transmissions, batteries, electric engines, fuel cells, performance electronics, and NVH (Noise Vibration Harshness) analyses.

In addition to the focus on the automotive industry, benchmarking programs are carried out for the commercial vehicle field, for agricultural machines and construction machines, and for other technical products.

In a typical benchmark program, FEV procures the target vehicle and equips it with the corresponding measurement technology. Initial tests regarding driving performance and energy consumption can be carried out as part of “micro benchmarking” without damaging the vehicle. For further detailed testing, special measurement technology is incorporated into the system to be analyzed. Specific driving cycles and driving tests on real roads, test tracks, or chassis dynamometers provide detailed measurement data. After the dismantling of the vehicle, FEV engineers place the main components to be analyzed on the test bench. These include the combustion engine, the transmission, the high-voltage battery, or the electric engine. Power characteristics are recorded and measurement data is transferred to FEV scatterbands in order to compare them with other measurement results in the FEV database.

After performance tests have been conducted, FEV Cost Engineering experts analyze materials, manufacturing and assembly processes and carry out a detailed should-cost calculation. The cost analysis provides an extensive cost breakdown and shows key cost drivers. Thanks to the achieved cost transparency, cost reduction ideas can be generated and target costs can be determined. FEV provides a unique overall package of benchmarking services with core findings for your developments and your corporate success.

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