E-car battery: Safety first, even off the road

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E-car battery: Safety first, even off the road-e-car

What’s good for the road can’t be so bad for storage. The article deals with the storage of lithium batteries, for which – in contrast to the ADR transport law – there are still no legal regulations. LogBATT, manufacturer of storage, quarantine and transport boxes for large HV batteries from the automotive industry in Europe, gives an insight into what is important when handling e-car batteries.

The fact that lithium-ion batteries, thanks to their technology, represent new opportunities, but also challenges and dangers, is no longer a secret and has already been described in many specialist articles. However, since one can no longer only speak of a temporary marginal technology, but of a mass market that is growing with incredible force and dynamic speed despite the Corona crisis, more and more participants and their organizations are being faced with new challenges at the same time and worldwide.

The unbelievable dynamism can be seen very well in the ADR dangerous goods regulations that have grown over the years with regard to lithium-ion batteries, which have even managed to get their own danger label (9A). The fundamentally nice thing about this legal regulation – one can discuss the meaning and usefulness of some requirements in detail – is that one can orientate oneself legally. As soon as someone is on public roads, the ADR applies. So far, so clear.

The situation is different when it comes to internal transport and, above all, storage. Who can help you here, what can you use as a guide? The Hazardous Substances Act, more precisely the Technical Rules for Hazardous Substances (TRGS) would be obvious – but lithium-ion batteries as objects are not formally included. So what can you do? Waiting for that to be fixed one day? Hardly, safe solutions are already needed now, apart from the fact that the laws of battery technology and the dynamics of distribution are lagging behind anyway.

However, reinventing the wheel does not always have to be necessary. It is worth looking into possible solutions that are based on existing dangerous goods legislation.

Building law aspects

If you look at the requirements of the individual building authorities with regard to the approval of storage facilities for lithium-ion batteries, the following protection goals are often – in brief – pursued:

  • Preventing the spread of a battery fire,
  • Collect contaminated extinguishing water.

As a concrete implementation, a separation of the premises is often required, i.e. only lithium-ion batteries may be stored in certain sections and nothing else. In addition, these sections are then often limited to a certain number of batteries, usually by total weight.

In order to contain a potential battery fire and prevent it from spreading to adjacent batteries, there are also special requirements for sprinkler systems. The current best method of fighting fires is to use the cooling effect of the water to slow down the reaction in the batteries. In addition, adjacent areas are often provided with F 90 walls, doors and gates so that a fire can propagate as far as possible to the entire building.

Many of the conditions mentioned can be found from the leaflet VDS 3103: 2019-06 (03) of the Total Association of the German Insurance Industry (GDV), which is often called and cited and cited in connection with storage and, of course, resort to the property insurers and also the authorities. But already the first topics are apparent, which are not yet regulated, for example for prototypes or batteries with high performance. It is especially noticeable that test with high energy content lithium-ion batteries have not yet been carried out. Exactly this area, expressed by the automobile, bus, truck, train and ship area, will grow at least 20-30% per year in the next 10-15 years.

Storage in safety cabinets

More and more solutions can be found in the storage area that use existing F 90 safety storage cabinets for hazardous substances. If you take a look at the requirements, for example from the DIN 4102-2 standard (fire behavior of building materials and components) for achieving fire resistance class F 90, it quickly becomes apparent that this approach only corresponds to the real conditions to a limited extent. With a defined fire from the outside, the structural integrity is to be ensured over a certain time and temperature profile.

As real tests have shown, the batteries can react within a few seconds or minutes, with large amounts of smoke gas being emitted suddenly. Per kilogram of lithium-ion batteries, between 180-300 liters of smoke gas can arise, which is a mix of 20-25 toxic to explosive gases. The battery fire also takes place from the inside out and not from the outside in. Deletion in the narrower sense is not possible.

E-car battery: Safety first, even off the road-e-car

Dangerous goods law reflects reality somewhat better. If you look at the current regulations in ADR for UN 3480 (lithium-ion batteries), you can see a clear system. A distinction is made within the batteries based on their hazard potential: the more dangerous, the higher the requirements, such as special, UN-approved hazardous goods packaging for transport. A transport safe and with a successful UN 38.3 test tested lithium ion battery is potentially less dangerous than a damaged battery which has to be transported under the requirements of Special Provision (SV) 376. Even for the first prototypes that are to be transported according to SV 310, packaging instructions P910 or. LP905 requires special packaging with safety precautions to protect against dangerous heat build-up.

If you take a closer look at SV 376, which deals with the exciting topic of damaged batteries, a distinction is made here again between batteries that are damaged, but for which a possible risk can be ruled out under normal transport conditions, and those that are damaged which transport safety cannot be guaranteed. If the latter category applies – that for critically defective lithium-ion batteries – a special permit from the national competent authority or a so-called procedure specification is required. The latter is in the P911 or. LP906 and represents the supreme discipline of battery transport. Here the conditions are particularly high.

The P911 or. LP906 was one of the major innovations of the ADR 2019 in terms of lithium-ion batteries, which had its predecessor in the then Multilateral Agreement M307. The intention behind this regulation was primarily to define the basic requirements for properties for dangerous goods packaging that withstand a damaged battery in the worst-case scenario (i.e. a thermal runaway). Furthermore, it was correctly recognized that not only flames but also, due to the lithium technology, the large amount of smoke gases pose a very special hazard potential, especially the toxic gas hydrogen fluoride (HF).

According to the motto “higher, faster, further”, there is a trend towards ever higher power densities, especially in vehicle drive batteries, which should ensure ever greater ranges. As a result, the nominal energy densities are constantly increasing and now reach up to 145 kWh in the automotive sector. This is also associated with a correspondingly high risk potential.

Example of P911/LP906 tested packaging

Specific test criteria for a package to be approved under P911 or LP906 are:

• The temperature of the outer surface of the complete package must not exceed 100 °C. A brief temperature peak of up to 200 °C is permissible.
• No flame must form outside the package.
• No splinters may escape from the package.
• The structural integrity of the package must be maintained.
• The packaging must. via a gas management system (e.g. B. filter system, air circulation, gas container, gas-tight packaging).

The test criteria imposed on the SafetyBATTbox from the provider LogBATT are shown as an example. This packaging system for critically defective lithium-ion batteries was tested under real fire tests according to LP906 and approved by the Federal Institute for Materials Research and Testing (BAM).

In the event of a fire, thermal insulation is required in order to be able to cope with the sometimes very high temperatures of over 800 °C inside. This special insulation is installed in all walls of the SafetyBATTbox, which is made of stainless steel. A special filter installed in the lid, together with the associated flue gas openings on the side of the boxes, ensure the necessary pressure reduction and filtering of the toxic hydrogen fluoride produced during the battery fire. In addition, a fire protection blanket and non-combustible fire protection cushions brought in when packing the critically defective battery(ies) develop a flame retardant effect. The tight inner trough and a bed of vermiculite on the bottom of the box together ensure that electrolyte escaping from the battery is collected and bound.

Conclusion and outlook

The approach of relating dangerous goods legal solutions (also for prototypes and/or damaged lithium batteries) to storage could create the necessary legal requirements and guidelines for the storage area. In the end, the right storage in secure and tested systems is like an insurance policy: in the best case scenario, you will never have to test them, but if you do, then you should be able to rely on such insurance.

Battery technology for mass use is still in its infancy. As with many new technologies, secure solutions will continue to develop rapidly with a growing market and new research findings. All market participants are now aware of the special hazards emanating from batteries, and there are existing solutions and systems for this. The advantages and disadvantages of individual systems can be discussed between market participants. It is important to find the best solutions.

VDA makes it clear: test summary no transport document

The German Association of the Automotive Industry (VDA) recently issued a recommendation on test summaries for lithium batteries. As of this year, manufacturers and distributors of lithium cells and batteries must submit a test summary in accordance with subsection 38.3.Provide 5 UN Manual of Tests and Criteria. It lists the necessary contents of a test summary.

The VDA writes: The international experts and government authorities involved in the discussion in the UN Expert Subcommittee on the Transport of Dangerous Goods and in developing the requirement for a test summary neither intended nor announced that the test summary would be an additional, mandatory transport document should be. Also, the test summaries do not have to be sent in advance to those involved in the carriage nor given during the actual carriage, but only made available on request. There are several ways to organize this (website, telephone number, queries along the supply chain, reference to manufacturer certificate etc.). So there is no obligation to carry along the supply chain, but for carriers, authorities, senders, customers, etc. the opportunity to approach the distributors and manufacturers involved at any time for identification, control or in the event of ambiguities and to request and request this test summary.
Even before the new regulation came into force on 1. Effective January 1, 2020, it was a prerequisite for the transportation of lithium batteries that they meet the requirements of Section 38.3 of the UN manual.

The VDA member companies and their suppliers have always met these requirements. Upon request, the companies involved in the transport will be provided with test summaries for plausibility checks. In accordance with the assessment of federal and state ministries as well as many – note not all – companies in the transport industry, the VDA recognizes in the new requirement under subsection 38.3.5 of the UN manual, however, there is no obligation for manufacturers and distributors to bring them.

About the authors: In this article, Philippe Helmle and Michael Knobloch from LogBATT take a look behind the scenes of the correct storage of lithium-ion batteries and show how fires can be avoided.

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