HyperG: the complete ISO 15118 charging stack, built in-house at Hypervolt

LONDON — 2 November 2026 — Hypervolt today introduced HyperG, a complete implementation of ISO 15118, the family of standards that lets an electric vehicle and a charger talk to each other: ISO 15118-2, ISO 15118-20 and DIN SPEC 70121, the protocol behind Plug & Charge, bidirectional charging and the next generation of smart EV charging. Designed and written entirely in-house in Rust, HyperG covers every layer of the conversation between a car and a charger, from the first signal on the powerline to a live energy session, in one lightweight and exceptionally fast stack.

ISO 15118 is the language of EV charging. It is how a vehicle and a charger agree on when to charge, how fast, in which direction, and how to pay, with no app, card or cable other than the one already plugged in. Every generation of the standard is covered: ISO 15118-2 and DIN SPEC 70121 for the cars on the road today, and ISO 15118-20 for bidirectional charging and the cars of the next decade. Most chargers speak these through a licensed third-party stack or a general-purpose runtime. HyperG takes a different path: the whole protocol family, built by the people who build the charger.

“Charging only works if the charger and the car understand each other perfectly, every time, whatever car and whatever year it was built. We didn’t want that to depend on anyone else’s code. So we wrote all of it.”

— Hardware squad, Hypervolt

See it in action.

A real ISO 15118-20 bidirectional session, from launch to session complete, recorded live in HyperG Mission Control. Full 1080p. Also on YouTube.

Every layer. One codebase.

A charging session is a stack of protocols, each handing off to the next. HyperG implements all of them natively, with nothing borrowed at runtime: no Java, no Python, no interpreter.

• Powerline pairing. SLAC over HomePlug Green PHY finds the car on the other end of the cable and sets up a private link.
• Discovery and transport. SDP discovery and V2GTP framing over IPv6, with TLS 1.3 and X.509 certificates for Plug & Charge.
• A native EXI codec. ISO 15118 messages are sent as EXI, a dense binary form of XML. HyperG generates its entire codec at compile time, straight from the official ISO schemas, so every message type is encoded with no hand-written schema code.
• Three standards, one state machine. ISO 15118-2, ISO 15118-20 and DIN SPEC 70121 are implemented side by side and negotiated automatically the moment a car plugs in, so a charger running HyperG talks to vehicles built today as fluently as the ones built next year.
• Both sides of the plug. HyperG implements the charger side (SECC) and the vehicle side (EVCC), so every session can be exercised end to end on a single machine before it ever meets a car.

Bidirectional by design.

A live ISO 15118-20 session in HyperG Mission Control. The car has flipped from charging at 22 kW to exporting 22 kW to the grid, mid-session, with no reconnect.

HyperG was built for energy that flows both ways. With ISO 15118-20, bidirectional power transfer is supported for AC and DC, in both scheduled and dynamic control modes, so a car can charge from the grid in the afternoon and power the home in the evening within a single session. Wireless power transfer and automated connection are part of the same stack, ready for the vehicles that will use them. And with ISO 15118-2, every AC and DC charging mode of today’s vehicles is covered, including Plug & Charge.

Ultrafast.

Charging protocols live or die on timing. ISO 15118 gives a charger a fixed budget to answer every request, and a missed deadline ends the session. HyperG decodes a request and encodes its reply in under a millisecond. Its codec is generated ahead of time rather than interpreted, there is no garbage collector to pause it, and the whole stack runs on Rust’s async runtime. The result is a charger that responds to the car in a fraction of the time the standard allows, with headroom to spare on even the smallest hardware.

A footprint that disappears.

Everything HyperG needs fits in a single, small, self-contained executable. There is no virtual machine to boot, no runtime to install and no megabytes of schema files to load. That efficiency is not a benchmark figure; it is what lets the stack run on modest, low-power silicon, start instantly, and leave the rest of the charger free to do its job.

Proven byte for byte.

A protocol stack is only as good as its conformance. HyperG ships with more than 1,050 automated tests, including over 500 reference vectors that are checked byte for byte against the industry reference EXI encoder, across ISO 15118-20, ISO 15118-2 and DIN SPEC 70121. Full sessions are exercised end to end against independent EV simulators, and the SLAC layer has been validated on real HomePlug Green PHY hardware, all the way to a closed contactor.

Mission Control.

The Protocol tab follows an ISO 15118-20 handshake message by message as it happens.

HyperG comes with Mission Control, a native desktop companion that turns a charging session into something you can watch. Choose a protocol, an energy mode and a payment method, launch the charger, and follow the handshake live. Flip the direction of power with a single control, cap discharge power on the fly, set a state-of-charge floor, and inspect every frame on the wire, both as raw EXI and fully decoded.

Session limits are applied live. Here discharge is capped at 11 kW and the charger follows immediately.

Tech specs

Performance and footprint figures were measured on a release build of HyperG on Apple silicon: codec timings are the mean across the ISO 15118-20 AC, DC and common-message reference vectors; memory is the physical footprint of the charger process while listening for a vehicle. Figures on embedded targets will vary. ISO 15118-20 support is in active validation and conformance work is ongoing.