Plug & Charge vs. Autocharge

A round up of 2022 and what’s to come

Charging Communication with ISO 15118 (July 2022)

I was just listening to the Out of Spec Studios podcast episode "What Plug And Charge And Autocharge Mean For The Ideal EV Charging Experience", interviewing Merge Electric Fleet Solutions CEO Glen Stancil.

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Here are the most important key takeaways:

▶ Tesla Supercharger network with the NACS option offers Plug & Charge (PnC).

▶️ Autocharge is simple and accessible, just requires reading the EV's MAC address. But it's not digitally secure as the MAC address can be spoofed in theory (requires man-in-the-middle attack), although not as easy as spoofing an RFID card. Therefore not really safe to use for public charging.

▶️ Autocharge identifies a vehicle (although not unique, see rolling MAC addresses for VW cars) not the entity that’s responsible for payment of the charging process. There's no central clearing house, so you need to register your EV at each charging network anew.

▶️ Autocharge is considered a bandaid and stopgap until the digitally secure (TLS, X.509-based PKI, digital signatures) and more user-convenient PnC becomes ubiquitous (with the help of e.g. Hubject)

▶️ Every car OEM is on its path to PnC, may take til model year 2026/27 but we‘ll get there.

▶️ PnC is more reliable and has a higher success rate than app and RFID and credit card authorisations.

▶️ Multi-contract handling is important. Right now most OEMs control the installation of the PnC Contract Certificate, but e.g. BMW Group the user to choose which contract certificate (and therefore MSP) to choose. This will have to become standard among car OEMs for a true breakthrough of PnC.

▶️ Autocharge is good for e.g. fleets, i.e. behind the fence applications without payment where only vehicle identification is relevant. However, PnC could become relevant for fleets if they open up for depot sharing.

▶️ Neither Autocharge nor PnC allow identification of vehicle make, model and year. For that we'd have to introduce a new value-added service for ISO15118 (a task for CharIN in my opinion).

▶️ For now Plug & Charge has the momentum of the industry, but other forms of authorisation and payment are imaginable in the future, e.g. one-time ephemeral PCI tokens via e.g. Apple Pay/Apple Car Play or Google Pay/Android Auto (in collab with Mastercard and Visa). But automakers have to want to do that, not likely anytime soon.

▶️ Most chargers, even Level 2, do support PnC HW-side (PLC modem), they just may not have the right software installed yet.

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If you want to learn everything there is to know about Plug & Charge, then head over to my whitepaper. It contains all my knowledge (as co-author and implementor of ISO 15118) on this topic.

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What do you think about Plug & Charge and Autocharge, and what are your plans to bring Plug & Charge to market? Let me know on LinkedIn.

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.

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Marc Mültin