--- title: High Voltage or Low Voltage? Getting EV Electrical Architecture Decisions Right description: How EV and hybrid engineering teams should split HV and LV domains, why 48V is gaining ground, and how EMB Power's Raptor-based control modules support both. --- [Skip to content](https://blog.emb-power.com/high-voltage-or-low-voltage-getting-ev-electrical-architecture-decisions-right#main-content) ![EMB\_Power\_Logo](https://blog.emb-power.com/hs-fs/hubfs/EMB_POWER_logo-16x9-tp-1.png?width=250&height=140&name=EMB_POWER_logo-16x9-tp-1.png) Open main navigation Close main navigation - [Contact us](https://www.emb-power.com/contact-us) [Contact us](https://www.emb-power.com/contact-us) Nov 13, 2026, 9:18:34 AM # High Voltage or Low Voltage? Getting EV Electrical Architecture Decisions Right [EMB Power Team](https://blog.emb-power.com/author/emb-power-team) Share: [facebook-f icon](http://www.facebook.com/share.php?u=https://blog.emb-power.com/high-voltage-or-low-voltage-getting-ev-electrical-architecture-decisions-right) [linkedin-in icon](http://www.linkedin.com/shareArticle?mini=true&url=https://blog.emb-power.com/high-voltage-or-low-voltage-getting-ev-electrical-architecture-decisions-right) [Twitter icon](https://twitter.com/intent/tweet?url=https://blog.emb-power.com/high-voltage-or-low-voltage-getting-ev-electrical-architecture-decisions-right) [pinterest-p icon](http://pinterest.com/pin/create/link/?url=https://blog.emb-power.com/high-voltage-or-low-voltage-getting-ev-electrical-architecture-decisions-right) [envelope icon](mailto:?body=https://blog.emb-power.com/high-voltage-or-low-voltage-getting-ev-electrical-architecture-decisions-right) \

Getting the high-voltage (HV) and low-voltage (LV) split right, early, is one of the few architecture decisions on an EV or hybrid programme you can't easily unwind later. Get it wrong and you're re-routing harnesses, re-certifying isolation boundaries, or discovering a control module can't do what the rest of the vehicle now needs from it. EMB Power works through this decision with engineering teams every week, as the UK and EU's exclusive partner for New Eagle's Raptor and OpenECU toolchain — this is the framework we use.\ \

HV and LV in an EV, in plain terms\ \

High-voltage systems, typically 400V and increasingly 800V, carry the energy that actually moves the vehicle: battery packs, inverters and traction motors. Low-voltage systems, historically 12V and now increasingly 48V, run everything else — lighting, infotainment, sensors, pumps and body control. The two domains need to be kept physically and electrically separate (galvanic isolation, dedicated DC-DC conversion between them) for the same reason you don't want a fault on a sensor circuit propagating into a 400V+ bus: safety and serviceability both depend on that separation holding.\ \ \\
Feature\\High Voltage (400V–800V)\\Low Voltage (12V / 48V)\\ \\Main purpose\\Traction, charging, inverter and motor power\\Lighting, infotainment, body control, pumps, sensors, ECUs\\ \\System control\\Domain-specific ECUs with isolated diagnostics and calibration\\Zone or body controllers (e.g. a general control module) with high I/O flexibility\\ \\Chief risks\\Arc flash, thermal management, insulation failure\\Overload as device count grows, wiring complexity, CAN bus saturation\\ \ \

Why more EV programmes are moving LV from 12V to 48V\ \

The short answer: 12V is running out of headroom. Electric steering pumps, more sensors, higher-draw infotainment and increasingly networked body functions are pushing LV current demand up, and at 12V that means thicker cable, more connectors and more heat. 48V delivers the same power at a quarter of the current of a 12V system, which is why chipmakers and harness suppliers alike are publishing material on the shift — TE Connectivity's own analysis of 48V automotive architectures describes a theoretical copper saving in the wiring harness of more than 85% versus an equivalent 12V design, alongside a large drop in resistive power loss \(TE Connectivity, 2025 whitepaper)\. That figure is a theoretical, like-for-like calculation rather than a guaranteed result for every harness design, so treat it as directional rather than a number to put in your own spec sheet without re-deriving it for your architecture.\ \

Zonal architectures amplify the effect: instead of running every LV device back to a central point, a zone or general control module sits physically close to a cluster of loads — front, mid, rear — and talks back to the rest of the vehicle over CAN FD, LIN or Ethernet rather than a dedicated wire per function. Fewer long runs, fewer failure points, and a controller that's doing power switching, diagnostics and data logging in one place rather than three.\ \

Where EMB Power fits: Raptor hardware and tooling for both domains\ \

As the exclusive UK/EU partner for New Eagle's Raptor platform — and, following New Eagle's 2026 acquisition of OpenECU, for the OpenECU toolchain too — EMB Power supplies and integrates the control modules and software that sit on both sides of the HV/LV boundary, and does the engineering work to get them into a vehicle correctly specified and calibrated:\ \