Why We Choose the Best: Pionix × Omron
We need reliability by design. Omron's G9KC-4A1B relay is the designated relay in our ChargeBridge AC reference design - here's why we chose it.
The Standard We Hold Ourselves To
At Pionix, we build the software backbone for EV chargers used around the world. But software is only as reliable as the hardware it runs on. That’s why we don’t just recommend components — we test them, qualify them, and stand behind them. When we design a reference board, every component on it has earned its place.
The Omron G9KC-4A1B is one of those components.
The Announcement: Pionix × Omron
We are proud to announce that Omron’s G9KC-4A1B DC12 relay is the designated relay in our AC reference desgin for ChargeBridge — the open-source AC satellite board built around the Pionix ChargeBridge module. This isn’t a theoretical recommendation. It’s the relay we use, the relay we publish, and the relay we actively recommend to every OEM building on top of our reference designs and Pionix ChargeBridge.
Technical Deep Dive: The G9KC-4A1B
The G9KC is a 4-pole PCB power relay purpose-built for the demanding environment of three-phase AC EV charging. It addresses one of the most stubborn hardware challenges in charger design: heat.
- Ultra-Low Contact Resistance: 6 mΩ max. This is the lowest on the market for this relay class. Less resistance means less heat generation at high currents — directly translating to more reliable charging sessions and longer component lifetime.
- 4-pole, 40 A switching at up to 480 VAC — ideal for 22 kW three-phase AC chargers, the dominant standard for European commercial and residential installations.
- Compact PCB-mountable form factor (W35 × L58 × H47 mm) — enabling slimmer enclosure designs compared to traditional contactors, while eliminating complex wiring harnesses.
- Auxiliary contact (Form B) — the 4A1B variant includes a SPST-NC mirror contact for reliable fault detection, fully conforming to IEC 60947-4-1 mirror contact requirements.
- IEC 62955 certified — meeting the high short-circuit withstand requirements (Inc=10 kA, In≤32 A) that are mandatory for EV charging applications in Europe.
- PCB automation-ready — by replacing wired contactors with a PCB relay, assembly can be fully automated, reducing wiring labour and eliminating a significant source of field failures.
Why Omron Convinced Us
Component selection at Pionix is never just about a datasheet. We evaluate performance under real charging conditions, long-term availability, certifications, and — critically — the quality of engineering support behind the product.
Omron passed on all fronts.
The G9KC’s thermal performance under sustained high-current loads is exceptional. In our CB-SAT-AC validation testing, it demonstrated consistent behaviour across thousands of switching cycles without measurable contact degradation. The low heat generation has a compounding effect on the broader board design: surrounding components run cooler, thermal derating margins improve, and overall system reliability increases.
Beyond performance, Omron’s engineering team provided responsive, technically grounded support throughout our integration process. That kind of partnership — where the supplier understands the application and engages with the engineering challenges — is rare, and it matters to us.
The Open-Source Reference Design
The CB-SAT-AC is Pionix’s open-source AC satellite reference design for Pionix ChargeBridge-based systems. It is freely available on GitHub and serves as a validated blueprint for OEMs developing three-phase AC charging controllers.
By publishing our full reference design with a qualified BOM, we eliminate weeks of component selection and qualification work for every manufacturer building on Pionix ChargeBridge. The G9KC-4A1B is in that BOM because it is the right relay for the job — not because of a commercial relationship, but because it performs.
A Shared Commitment to Quality
“The G9KC was developed specifically for the thermal and certification challenges of three-phase EV charger design. We are glad to see it adopted in an open reference design that helps the entire industry move faster.” — Omron
“We only put components in our reference designs that we trust completely. The G9KC earned that trust through its performance and through Omron’s support. We recommend it without reservation for any Pionix ChargeBridge-based design.” — Dr. Marco Möller, CEO, Pionix
Get Started
The CB-SAT-AC reference design including full BOM is available now on GitHub.
[View the CB-SAT-AC on GitHub]