Second Use and Second life for Electric Car Batteries – DKE Prestandard Conquers Europe

DKE: Mr. Zeyen, Mr. Hetzler, you were involved in creation of the VDE V 0510-100 prestandard for repurposing electric car batteries. How did this initiative come about?

Zeyen: Several car manufacturers had already started working on this problem, even before the prestandard was created. One of our customers had also asked us to figure out how electric car batteries could be reused in stationary applications prior to recycling in line with current EU guidelines. Although various generic standards existed, there was no information available on how to ensure safety and compliance after repurposing.

At that time, I was sitting with Bardo Quint at Frankfurt Central Station, and within twenty minutes we developed an initial idea of what a prestandard on this topic could look like. We presented our idea at the following DKE meeting and discovered that we were preaching to the already converted. After an initial call for experts, we sat down at the table with more than thirty colleagues. This resulted in formation of the Working Group DKE/AK 371.1.14, which I supported as project manager during the work on the prestandard which was later handed over to Bardo.

Hetzler: By the way, the initial focus was not placed on reusing vehicle batteries that had already been used, i.e. second life, but rather on second use. This included batteries that had been stored due to overproduction and weak sales figures during and after the COVID-19 pandemic. Manufacturers could no longer use them in vehicles, so the question was: “What should be done?” Our first pilot projects ran in parallel with development of the prestandard.

DKE: That sounds like a normative project that addresses a clear need and one that was strongly driven by the manufacturers. What do you think is the motivation behind it all?

Zeyen: The idea was indeed born out of practical experience – motivated by the fact that a car battery can still be very powerful before recycling, and at the same time it can also be regarded as a cost-effective stationary storage device. For example, when an electric car battery has a capacity of 70 percent, this capacity is still many times higher than that of a typical home storage device. With an increasing number of electric vehicles and a constant increase in the number of batteries, this combination promises to give rise to an interesting market.

In addition, the European Battery Regulation now provides a statutory incentive that sets requirements for reuse and recycling rates – so we were already a big step ahead of this development in terms of standards.

DKE: The focus is on stationary use in industry. We don’t want to go into too much detail here, but what does VDE V 0510-100 describe in very broad terms?

Hetzler: We focused on three areas: electrical safety, functional safety, and exchanging experience. Functional safety is ensured when a product meets the requirements that apply to its use in a specific system. In our case, there are specifications according to ISO 26262 for the use of lithium-ion batteries in vehicles, and there are general specifications according to IEC 61508. If you change the intended use and thus the system as well, then how do you make the transition from one standard to another? We looked into this and developed guidelines on how this problem can be solved in practice.

Zeyen: We also included tips from practitioners for practitioners, based on the experience shared by those involved. For example, a car battery undergoes a test routine every time the engine is started – when it is stationary it is in use 24/7. Well, what does that mean for repurposing? These are sometimes very complex questions.

DKE: You yourself work in consulting, engineering, and prototyping for automotive projects. What experience have you gained in applying the standard?

Zeyen: Before the prestandard was introduced every reputable manufacturer wanted to have their approach to repurposing reviewed by an external body. This applies both to subsidiaries of vehicle manufacturers that are active in this field and to secondary users who have good connections to the automotive industry. The prestandard has made discussions with testing institutes easier, because now there is a uniform basis.

Hetzler: Ultimately, the standard creates the basis for the safe reuse of batteries at a professional level. It is not enough to simply remove the battery and create a state where it can deliver energy. When it is integrated into the vehicle’s electrical system, the battery issues error messages that are tailored to its use in the vehicle when necessary. What is important is to determine how these messages should be evaluated in stationary use.

DKE: You already provided some information on what to look out for when repurposing. We don’t want to reveal too much more at this point, as the DKE HotSpot in Frankfurt on September 29th will deal with this topic in depth. Are there any other relevant aspects besides the technical issues that you would like to share with manufacturers?

Zeyen: Yes, I do in fact see another issue in that case. In spite of all the enthusiasm, we mustn’t forget that second-use or second-life batteries have to compete with cheap new batteries from Asia. Although they are sustainable in terms of the circular economy and maximizing the service life of technical products, they have less residual capacity and are technically outdated as well. This means that, as an entrepreneur, I have to carefully consider how much effort I am willing to put into making the application safe – after all, such efforts have to remain economically viable and pay off in the end.

DKE: Have you gotten any feedback from other companies with regard to the practicality of the standard? Is there room for improvement, or was it spot on?

Zeyen: It was absolutely spot on in 2023, as shown by the huge response. But we made a very clear decision at the time in order to reach our goal as quickly as possible. That is, we only focused on use of the complete battery as stationary storage in industry, and not on the use of individual modules. This was the right decision, but this second scenario now needs to be followed up.

DKE: We have seen that the prestandard is highly relevant. And it is now set to become a model for repurposing in Europe as part of the European Battery Regulation. So what’s happening at the moment?

Hetzler: With its standardization mandate M/579 the European Union has called for the creation of a normative framework for repurposing. In this context, the German prestandard has become the guideline for the European standard. We have provided a great deal of input from Germany, which has also been well received. 

The CENELEC committee CLC/TC 21X is currently working on implementation. Thanks to the preparatory work that has already been done, the harmonized European standard was able to be developed relatively quickly, even if we are no longer able to meet the European Commission’s original implementation target.

DKE: When this standard is published, including the specifications for the use of individual modules, won’t this give rise to completely new applications?

Hetzler: That’s right. Like I said, use of the entire vehicle battery is limited. It has a fairly large housing and, in general, it cannot be vertically mounted. This means that we currently have applications as large-scale storage for industry to buffer peak loads and thus reduce energy costs. 

However, if I can use individual modules, then I have significantly more flexibility in terms of application. I can combine them as required, am free to choose the final dimensions, and therefore I can also construct smaller storage units in a practical manner.

DKE: Finally, a quick word about the DKE HotSpot in Frankfurt at the end of September. Why should the users of standards definitely take part?

Zeyen: It is a young product field and there are not many opportunities to exchange ideas with other practitioners. In addition, this format offers the opportunity to make an impact standardization and contribute your own ideas. It is definitely worthwhile, and we look forward to the exchange.

DKE: Thank you very much for talking to us!

Editor's note: Unfortunately, the workshop had to be cancelled for organizational reasons.

Electromobility is a leap innovation that requires new, overarching systems thinking. In order to position the German economy successfully in the field of mobility, it is important to incorporate the positive effects of norms and standards into the development process from the very beginning and thus fully exploit them. The same applies to the latest developments in the field of mobility - micro-mobility. You can find further content on this subject area in the