The battle between ISO 15118 and DIN SPEC 70121

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Marc Mültin
updated
June 30, 2021
published
November 18, 2017
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A common question I receive from the EV community is whether there is a difference between ISO 15118 and DIN SPEC 70121. The answer tends to leave many of you quite surprised. This is an essential distinction to understand in order to make sure your products are interoperable. The German technical specification DIN SPEC 70121 is based on an early, unpublished version of the ISO 15118 standard and defines digital communication between an electric vehicle and a DC charging station. DC stands for direct current, which means DIN SPEC 70121 covers only the DC charging mode whereas ISO 15118 covers both AC (alternating current) and DC charging modes.

The ISO 15118 series has evolved greatly since the first publication of DIN SPEC 70121 and this has lead to a host of technical differences between DIN SPEC 70121 and ISO 15118. DIN SPEC was first released in 2012 and updated in 2014, whereas the first version of the technical specification of ISO 15118 was released in 2014 and version 2 is on its way.

It’s like a dialect of the same language. If you don’t understand that dialect, then it doesn’t matter if it’s the same language or not: you can’t move forward with the conversation.

This means that a charging station that only supports ISO 15118 cannot charge an EV that only speaks DIN SPEC 70121. But if the EV is able to speak both dialects, then they can successfully enter a charging session – and vice versa. That’s where it becomes very important that you understand and apply this knowledge to your product line and future innovations.

Another key distinction between ISO 15118 and DIN SPEC 70121 is that the latter does not support Plug & Charge, meaning: no secured communication via Transport Layer Security (TLS), no digital certificates, and no XML-based digital signatures so authenticity and data integrity can’t be ensured. Also, no smart charging is possible via DIN SPEC 70121, meaning: you can't send charging schedules to the EV to make it charge in a smarter, more grid-friendly way.

DIN SPEC 70121 was created as an interim solution to get the market up and running until ISO 15118 was released. Unfortunately, it still prevails in various test installations at the ISO 15118 Testing Symposia (Video 1 of my course “Revolutionize Electric Vehicle Charging” has visuals from the most recent symposia). But DIN SPEC’s days are numbered, as ISO 15118 and its wide range of additional features fast become the industry standard.

We’ll dive deeper about this important distinction in the online course Master the Communication for Charging Electric Vehicles. Please contact me if you have further questions or need additional clarification.

Marc Mültin
November 18, 2017
Sara
DEF:

Sara

Sara stands for Station Analytics and Remote Administration

OCA
DEF:

OCA

The Open Charge Alliance is the official body that specifies OCPP 2.0.1 and defines a set of certification profiles. Each profile tests a certain set of functionalities. Depending on the functionality of your charger or CSMS, you might want to certify for either a subset or all of these profiles.

CI/CD
DEF:

CI/CD

Continuous Integration / Continuous Deployment (CI/CD)

Scotti
DEF:

Scotti

Scotti stands for Simple Compliance Testing Tool for Interoperability.

EXI
DEF:

EXI

Efficient XML Interchange (EXI) is a very compact representation of XML. All ISO 15118 messages are defined in XML. EXI improves serialisation and parsing speed on embedded devices (like an EV and a charging station controller) and allows more efficient use of memory and battery life, compared to standard (textual) XML.

MQTT
DEF:

MQTT

The Message Queuing Telemetry Transport (MQTT) is a lightweight, publish-subscribe network protocol that transports messages between devices.

CSMS
DEF:

CSMS

A Charging Station Management System (CSMS) helps you monitor, maintain, and control your charger network.

ACD-P
DEF:

ACD-P

Automated Connection Device (ACD), a conductive charging concept that doesn't require a person to plug in the charging cable. A first implementation is ACD-P, where 'P' stands for 'pantograph' charging of buses.

PLC
DEF:

PLC

Power line communication, a communication technology that enables sending data over existing power cables.

SLAC
DEF:

SLAC

Signal Level Attenuation Characterisation (SLAC) is based on power line communication (specifically HomePlug Green PHY) and is a protocol to establish the data link between the EV and the charging station via the charging cable.

CPO
DEF:

CPO

Charge Point Operator, the entity monitoring and managing an EV charger network.