Engineering Power: Why OEMs Are Moving Beyond Relays

May 22, 2026

For decades, electromechanical relays have been a foundational component in machine power distribution. They’re familiar, easy to understand, and have served industry well in simple, low‑duty applications. But as machines become more electrified, connected, and intelligent, the limitations of relay‑based systems are becoming harder to ignore.

Today’s OEMs are asking more from their power architectures: faster switching, higher reliability, richer diagnostics, reduced wiring complexity, and survivability in increasingly harsh environments. Meeting those expectations has driven a clear industry shift toward smart, high‑current solid‑state power solutions.

The Limits of Traditional Relays

Electromechanical relays are inherently constrained by the fact that they rely on moving parts. Mechanical wear dictates a rated operational life, which is often acceptable for infrequent switching but quickly becomes a bottleneck in applications requiring high cycle counts or pulse‑width modulation (PWM), such as motor control or soft‑start loads.

Relays also struggle to scale with modern electrical systems. As battery‑powered equipment pushes toward higher DC voltages like 48V, finding relays rated appropriately becomes more difficult. On top of that, the relay coil consumes power continuously while energized, reducing overall system efficiency—an increasingly important metric in electrified machines.

Environmental robustness is another challenge. Shock and vibration can cause relay chatter, intermittent failures, or outright mechanical damage, making them problematic in off‑highway, agricultural, marine, and other rugged applications. Add in the reality of component obsolescence and unique relay packages, and long‑term serviceability becomes a real concern for OEMs.

Why Solid‑State Power Is Gaining Ground

Solid‑state switching eliminates many of these pain points by replacing mechanical contacts with semiconductor devices. The advantages are compelling:

• Dramatically longer life, with no mechanical wear
• Much faster switching, enabling PWM and advanced control strategies
• Higher efficiency, since there’s no coil current to maintain
• Integrated protection, such as overcurrent and overtemperature shutdown
• More compact designs, freeing up valuable panel space

Despite these benefits, misconceptions still persist. Some engineers assume solid‑state solutions are always too expensive, run too hot at high current, or sacrifice safety due to a lack of galvanic isolation. In practice, modern low‑RDS (on) MOSFETs, robust gate drivers, and thoughtful system design allow solid‑state switches to achieve performance and reliability comparable to—or better than—relays, with isolation added where required.

High‑Current Solid‑State Switching in Practice

Handling high current electronically does introduce design challenges, particularly around heat. Higher currents mean higher power dissipation, making careful PCB design, thermal management, and component selection essential. Choosing low‑resistance switching devices and parts with integrated temperature and current protection goes a long way toward mitigating these issues.

The payoff is significant. Solid‑state switches operate in microseconds rather than the tens of milliseconds typical of relays. They support soft‑start, motor speed control, and precise load management and they do it consistently over millions of cycles.

Many OEMs transitioning from relay modules to solid‑state power modules report meaningful improvements in uptime and reliability. Beyond simply switching loads, these systems provide real‑time insight into current drawing, faults, and operating conditions—data that was previously unavailable or difficult to access.

Built‑In Diagnostics Change Everything

One of the most powerful advantages of smart solid‑state power distribution is diagnostics at the load level. Features like overcurrent detection, short‑circuit protection, overtemperature monitoring, and open‑load detection allow issues to be identified precisely and immediately.

This fundamentally changes how machines are serviced. Instead of tracking down a blown fuse and poring over wiring diagrams, technicians can see clear, localized fault information such as which specific output experienced an overcurrent event. When diagnostics are logged over time, OEMs can start identifying recurring issues, common failure points, and opportunities for design improvement.

Modern HMIs further enhance this experience by presenting clear, descriptive fault messages rather than cryptic error codes, making troubleshooting faster and reducing downtime.

Reducing Wiring Complexity with Distributed Architectures

Traditional power distribution often results in long wire runs, dense panels full of relays and fuses, and countless terminations. This drives up installation time, increases cost, complicates diagnostics, and creates more potential failure points especially in high‑vibration environments where terminals can loosen or corrode.

Solid‑state switching alone doesn’t solve this but pairing it with distributed control over CAN does. By distributing I/O closer to the loads, OEMs can replace long ground returns and signal runs with short local connections, requiring only power, ground, and a CAN pair at each node.

The impact is substantial: simpler wiring diagrams, smaller and more modular harnesses, fewer terminations, reduced EMC susceptibility, and improved production consistency. Fewer wires mean fewer opportunities for mistakes and fewer issues to diagnose in the field.

Designed for Harsh, Real‑World Environments

Off‑highway, agricultural, and marine machines operate where vibration, temperature extremes, moisture, and chemical exposure are everyday realities. Electromechanical components are particularly vulnerable in these conditions.

Solid‑state power modules, when properly designed and sealed, are far better suited to survive. Rigorous validation including vibration and shock testing, operation at voltage and temperature extremes, and exposure to moisture and chemicals ensures these systems maintain both electrical and mechanical integrity over years of service.

The real proof, of course, is in the field. Modules that continue operating reliably for years under harsh conditions demonstrate the value of designing for durability from the start.

CAN Bus Done Right Enables Scalability

A robust power system depends on a robust communication network. “Doing CAN bus right” means designing with proper termination, respecting length, and speed limitations, managing bus load, and planning for scalability.

Common pitfalls such as inadequate termination or allowing bus traffic to grow unchecked can lead to intermittent, difficult‑to‑diagnose problems. In more complex systems, segmenting networks with gateways can keep latency manageable and communication reliable.

When implemented correctly, CAN makes machines far more adaptable. Adding new features or devices often becomes as simple as running power and a CAN drop, rather than redesigning harnesses. It also plays a critical role in diagnostics, safety, and overall system performance.

Bringing It All Together

Engineering power isn’t just about turning loads on and off. It’s about distributing energy in a way that’s safe, efficient, rugged, intelligent, and ready for the future.

Solid‑state switching, integrated diagnostics, reduced wiring through distributed CAN architectures, and ruggedized design all reinforce each other. The result is machines that operate longer in harsher conditions, are easier to service, and are far more extensible as new features and electrification demands emerge.

For OEM engineers designing next‑generation power systems, the advice is simple: look beyond individual components. Work with partners who understand your entire system and can help you build power distribution that supports reliability, serviceability, and long‑term innovation not just today’s requirements, but tomorrow’s as well.