Testing

In the past few years lithium ion batteries have found application in a wide variety of mobile devices such as laptops and mobile phones. Where the energy density is increased, however, the safety risk posed by the overcharging and possible destruction of the battery must be taken into account. Materials and designs with significantly improved safety features are therefore being developed. Lithium-polymer rechargeable batteries, for example, can be protected against overcharging by the use of special charge controllers. It is not yet clear which type of lithium-polymer battery will finally be applied in vehicles. Due to their polymer-film construction, lithium-polymer batteries present a very interesting option. A complete processing chain is available for their pilot production.

In addition to materials and system development, another focus is on designing and conducting different performance and safety tests in conjunction with appropriate analytical procedures.

High-voltage energy storage devices are a key element in electric and hybrid vehicles. Modern concepts include (lithium ion) battery systems, although the hybrid use of battery cells and capacitors could be possible in the future. Fuel cell technology also has significant potential, for example in combination with battery systems to extend range.

The testing and evaluation of energy storage devices is an important stage in the development chain for automotive applications. Due to the wide range of technical issues involved, a large number of different attributes must be evaluated and verified, e.g.

• electrical charging and discharging behavior
• electrochemical service life of cells
• behavior in accident scenarios (including crash, shock, intrusion, fire) and
• durability and system reliability during operation.

Depending on the specific needs of the customer, investigations are carried out on the cell, module or system level.

Networked services - comprehensive testing and evaluation facilities

In the service center the institutes of the Fraunhofer Battery Alliance combine their competences in the field of electric energy storage devices.
 The result is a comprehensive and holistic service portfolio which covers almost every aspect of the testing and evaluation of energy storage devices.
One focus of work is modern traction batteries, on the level of the cell, the module or the entire system.

The partners in the service center cover various aspects of the testing and evaluation of energy storage devices, which together form a comprehensive competence portfolio.

• The Fraunhofer EMI is a competent research partner for the vehicle safety, impact and crash research sectors, and is a leading institution in the field of safety research.
• The Fraunhofer ICT evaluates battery systems and their cell design. Abuse tests are carried out on a cell and module level, and damage and post-mortem analyses complete the institute's portfolio.
• The Fraunhofer ISE has long-standing experience in the field of battery system technology (construction of battery modules and systems, development of battery management systems) and battery tests (performance and aging tests), as well as modeling and the simulation of battery and energy systems.
• The Fraunhofer LBF is a highly qualified service provider for industrial partners in the field of operational stability and system reliability. Activities include loading data analysis, testing methods
  and accelerated tests for energy storage systems.

Our service portfolio covers all standardized tests, and also offers the possibility for customer-specific testing. Activities in the service center include the definition or development of relevant testing and evaluation programs. The service center also offers consultancy and additional research and development competences in this field.
The following tests can be carried out:

• UN transport tests
• FreedomCAR tests
• Safety tests on cells, modules and battery packs
• Analyses using different processes, e.g. CT
• Material characterization
• Load and stress tests
• Tests according to modern norms and standards (IEC, DIN, PVGAP, …)
• Freely programmable testing cycles
• Aging tests
• Evaluation of operational stability and system reliability of battery systems,
  including set-up and connection methods
• Casing and storage
• Electronics
• Cooling systems and elements

Fraunhofer EMI:

Crash lab: Three testing units for vehicle safety:

• Whole-vehicle crash-test facility (from 2012), battery testing stand and component testing facility
• Tests in a protected environment (blast lab)
• Comprehensive measurement technology, including gas analysis and CT

Fraunhofer ICT:

Comprehensive testing equipment for mechanical, electrical and thermal tests on individual cells.

• Chemical analysis of substances emitted on abuse
• Abuse tests in pressure containers
• Analysis of cell materials and components (e.g. REM, XRD, Raman, DSC, ICP-AES)
• Protective gas box to open and evaluate cells

Fraunhofer ISE:

• Over 140 test circles for batteries ranging from small button cells to large battery systems for traction and stationary applications.
• Performance test stand up to 1000 V, 600 A, 250 kW with CAN bus emulation
• 9 heated chambers and climate chambers, and various water baths
• Testing unit for batteries and energy management systems

Fraunhofer LBF:

• Various electrodynamic shakers up to 27 kN (RKV), including climate chamber
• Possibility of customer-specific test set-ups with servo-hydraulic excitation
• HV battery system test bench up to 600 kg for multiphysical test conditions (mechanical, electrical and thermal loads for battery tests)
• Scanning vibrometry (one- and three-dimensional)

The institute also has comprehensive measurement equipment, including for mechanical, electrical and thermal loads and stress.