Charging Communication with ISO 15118 (July 2022)

The issues with EU-funded research project Ultra-E - and what does it mean?

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We all know that the rise of e-mobility closely links to a charging infrastructure which is readily available, reliable, and sufficient regarding the number of charging stations installed. These are the primary concerns of those who asses for themselves if it is worth buying an electric vehicle (EV) or not. At the same time, we need to make sure that the business process of secure and tamper-free charging and billing is carefully addressed by all involved e-mobility market players, including automotive OEMs, charge point operators (CPOs), mobility operators (MOs, aka e-mobility service providers) and IT infrastructure providers. The challenge is to establish a smoothly running system which is secure, user-convenient, reliable, and interoperable between the participating actors.

This article sheds light on the ongoing activities in the EU-funded research project Ultra-E that sets out to tackle the issues as mentioned above.

ULTRA-E – A corridor of high-power charging stations across Europe

The primary goal of Ultra-E, a project co-funded by the European Union, is to establish a European-wide corridor of high-power charging stations. The project has a total budget of around 13 Mio Euros. It started off in 2016 and will proceed to the end of 2018. The Ultra-E project website still only provides rudimentary information, but I was told that more is in the pipeline. In total, 25 so-called Ultra-Fast-Chargers shall be installed on a corridor of more than 1.000 kilometres, with a maximum distance of 120 – 150 km between each charging site. Twelve of those chargers will be installed in Germany, five in the Netherlands, four in Austria, and four in Belgium. The chargers shall be able to reduce the charging time needed for a travel distance of 300 km from 1.5 hours to 20 minutes, thereby providing charging powers of up to 350 kW per charging station.

Project goals ISO 15118 and Plug & Charge

One of its project goals is to define the architecture and needed functionality for applying the ISO 15118 communication standard in real life and thereby realising the user-convenient Plug & Charge functionality for seamless authorisation, billing, and load control. With Allego in the lead, Ultra-E involves big players in the e-mobility and automotive industry, such as Audi, BMW, Renault, Hubject, Magna, and Smatrics.
As the implementation of ISO 15118 on a larger scale is one of the key technical challenges, this project is the first to realise the newly published VDE regulation VDE_AR_E_2802-100-1 that clarifies the "Handling of certificates for electric vehicles, charging infrastructure and backend systems within the framework of ISO 15118".
You may ask what the VDE is if you have never heard of this association. Well, the VDE Association for Electrical, Electronic & Information Technologies (German: Verband der Elektrotechnik, Elektronik und Informationstechnik) is one of the largest technical and scientific associations in Europe. Its activities include ensuring safety in electrical engineering, developing recognised technical regulations as national and international standards as well as testing and certifying electrical and electronic devices and systems.

ISO 15118 only defines the communication between electric vehicles and charging stations. To ensure a secure exchange of information for this machine-to-machine communication, we need to establish some degree of trust. This trust relationship builds upon the exchange of digital signatures and certificates that prove the identity of a communicating party - such as an EV or a charging station. Those digital certificates are based on Public Key infrastructures (PKIs). A PKI is a set of roles, policies, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates. The principal idea of what kind of PKIs are required is already written down in the ISO 15118 standard.

A VDE regulation for realising the needed Public Key Infrastructures

However, if there are no such PKIs established in the market to bring the complete Plug & Charge experience to life, then it's as if you built a brand-new and fascinating car - but forgot to put the engine in it. In order for the Plug & Charge functionality to work, we need to make sure that a so-called contract certificate that is linked to a legal charging contract from the mobility operator of your choice can be installed in the EV. This can be done either via the charging infrastructure during a charging process or a telematics link of the automotive OEM. That contract certificate, together with a digital signature (ECDSA), enables the EV to automatically authenticate itself for charging as soon as you plug in your charging cord or park above a wireless charging pad. Charging, billing, load control - all done without any further action needed from the driver (thus the expression “Plug & Charge” or “Park & Charge”).
The process of provisioning such a contract certificate involves a set of e-mobility market stakeholders that need to collaborate via well-defined interfaces to exchange the necessary cryptographic key material and digital certificates.
And that’s exactly what VDE_AR_E_2802-100-1 is all about: it fills the missing specification gap of ISO 15118 to realize this user-convenient Plug & Charge feature.

ISO 15118 Masterclass - helps you to understand the VDE regulation better

In my ISO 15118 Masterclass, published in February 2017, I provide a "Plug & Charge Video Tutorial" which helps you to understand the necessary business processes, IT infrastructure components, interfaces and implementation details addressed by the VDE regulation VDE-AR-E-2802-100-1.

Back in February, the VDE regulation was not yet published, but as I am head of the expert group which has been defining this regulation over a couple of months, I know exactly how it works. Back then I already believed that the industry deserves to be informed about this specification as soon as possible so this technology can be properly implemented in the market and be ready to meet consumer demand.

Luckily, the VDE regulation has finally been published on September 15th and can now be purchased via the website of the VDE publishing house.
So far, it is only available in German. However, the document has already been translated into English. After the review process is finished, this standard will also be available in English. I hope that the official publishing process will not take longer than a few weeks maximum.

ULTRA-E implements Plug & Charge according to VDE-AR-E 2802-100-1

Some of my clients are members of the Ultra-E project. That allows me to help and guide them while setting up the IT infrastructure and interfaces needed to finally make the last missing piece of the ISO 15118 puzzle available in the market.
Currently, only Daimler’s Smart electric drive and Innogy SE’s charging infrastructure support ISO 15118. However, the support of ISO 15118 is to some degree limited as long as the necessary PKIs are not yet deployed in the market. One can imagine that at least Audi and BMW, being part of this research project, will soon follow with ISO 15118-compliant EVs – my bet is either 2019 or 2020. They are also very likely to offer e-mobility services themselves and thereby contract certificates that are linked to their own charging contracts. As the after-sales market gets more and more important in the era of e-mobility and autonomously driving cars, this is a natural evolution of the product portfolio offered by automotive OEMs.

A central role in this project plays Hubject, an eRoaming platform that provides a digital B2B marketplace for services related to the charging of electric vehicles. They decided to broaden their product portfolio by implementing many of the roles defined in the VDE_AR_E_2802-100-1 regulation. For example, they operate so-called certificate authorities (CAs), such as the trust anchor V2G (Vehicle-to-Grid) Root CA, that sign certificates for e.g. CPOs, MOs or automotive OEMs. This is an essential cornerstone of the PKIs, needed to establish the trust relationship mentioned above. Hubject offers some more information on their website.
I don’t want to get into too much detail of what a CA does and how this trust relationship is exactly established because that would be a topic big enough for an article of its own. However, if you like, you can get a sneak peek into the ISO 15118 Manual which provides a free extract from each chapter. Chapter 4 on the "Certificate Concept" and chapter 5 on "Certificate Provisioning" teaches you all you need to know to understand the PKI concept in ISO 15118.

Hubject has been closely collaborating with Allego, Audi, BMW, Smatrics, and its subcontractors to clearly define an interface specification with all the messages and parameters needed to conform to the VDE_AR_E_2802-100-1 regulation, thereby using RESTful web services. This document will be published at some point in time during the dissemination process of the Ultra-E project to ensure interoperability and to help other market players that want to implement this promising communication standard.

As the VDE regulation is a document originated by a German organisation, it is not sure yet how the international acceptance will evolve over time. I hope that all interested parties will take a close look at this specification (I will post an update here as soon as it is available in English) and help to improve it over time instead of trying to reinvent the wheel.

User group for implementation-specific issues

The questions and discussions that arise during the implementation of the VDE regulation are valuable feedback that will in turn influence the next version of this standard. Until then, a forum has been put into place, similar to the ISO 15118 User Group, to exchange and discuss questions and answers regarding the implementation of this specification.
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The goal is to form and document a common understanding of implementation details and thereby ensure that different implementations behave compatibly.

Marc Mültin

Marc, the Founder and CEO of Switch, has over 13 years of experience in the e-mobility space and holds a PhD in Computer Science. He is the leading global expert and co-author of international EV communication standards (ISO 15118 & OCPP 2.0.1) that underpin the Switch platform.

— Connect with

Marc Mültin

What is ISO 15118?

As part of the Combined Charging System (CCS), ISO 15118 is a communication protocol covering all use cases for charging electric vehicles across the globe.

Project Ultra-E realises key public infrastructures are needed for Plug & Charge

The issues with EU-funded research project Ultra-E - and what does it mean?

ULTRA-E – A corridor of high-power charging stations across Europe

Project goals ISO 15118 and Plug & Charge

A VDE regulation for realising the needed Public Key Infrastructures

ISO 15118 Masterclass - helps you to understand the VDE regulation better

ULTRA-E implements Plug & Charge according to VDE-AR-E 2802-100-1

User group for implementation-specific issues

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