Batteries Under Stress

| Environmental Testing

Climatic chamber for battery testing includes a CT scanner for condition monitoring

Weiss Technik develops World’s First Test Bench for Stressing Energy Storage Devices under CT surveillance

Test chamber and equipment specialist, Weiss Technik has developed a test bench for lithium-ion batteries with high energy density. Developed at Weiss Technik’s German headquarters, the testing facility, at the EU’s Joint Research Centre (JRC), is the first to enable the use of computer tomography (CT) images during battery operation. The first test facility of its kind in the world, it will help to improve the safety, durability and performance of batteries. Another objective is the development of EU-standards.

The market for lithium-ion batteries is growing rapidly – and so is the need for specialised test laboratories. Due to their high energy density, lithium-ion batteries are used in electric cars and bicycles, as well as for storing electricity generated by solar and wind energy. They are exposed to major environmental influences, such as heat, cold and humidity. Investigations on energised temperature and climate tests are carried out using a CT scanner in order to improve their safety, durability and performance. With Weiss Technik’s new environment simulation technology, the changes these batteries undergo in a wide range of different environments during operation can now be investigated in order to identify weak spots and optimisation potentials. For this purpose, the Device under Test (DUT) is mounted on a rotating plate and examined from all sides by a CT scanner. The complete 3D data for the battery generated in this way allows conclusions to be drawn about its current state.

Explosion-proof design

As the batteries are subject to extreme stress during testing, there is a risk of exothermal reaction. Such an explosion would endanger battery, testing technology and testing personnel alike. For this reason, an external test space has been constructed for ATEX (ATmosphere Explosive) Zone 1. Furthermore, the safety precautions are also suitable up to hazard level 6. Four different gas sensors monitor the test space, two more the lead-clad installation room, in order to detect leaks in the battery DUT. To protect against the radiation of the CT, the test space is located in a lead-coated, air-conditioned installation room. Permanent oxygen-controlled inerting is carried out as a protective measure in order to prevent fires, meaning that just enough nitrogen (N2) is introduced as is necessary from a safety point of view. If rapid pressure equalisation is required, this is achieved via a pressure relief flap.

Standards development

The test facility is a project operated by the EU’s Joint Research Centre (JRC) in Petten, the Netherlands. It offers researchers access to cutting-edge technical equipment in order to research the optimisation potentials for battery performance and safety. Weiss Technik planned and implemented the entire climate testing facility, including all safety devices, as a partner to industrial CT specialist diondo, who provided the CT scanner. The prestigious Fraunhofer-Gesellschaft institute was commissioned with building the testing facility and developing future EU standards for battery storage systems. It also carried out research to identify a suitable material that enables the CT radiation to penetrate while ensuring gas tightness of the test space at the same time.

Malcolm Youll, Managing Director at Weiss Technik UK Ltd, said: “Weiss Technik has been developing test systems for lithium-ion batteries for more than twelve years, offering sophisticated technology to test the safety, reliability and performance of electrical energy storage devices for vehicles under all thermal, climatic and mechanical stresses. Our customers benefit from our experience, whether they are start-up companies or automobile manufacturers. We pride ourselves in helping them make their energy storage systems as safe as possible.”

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