A variable resistive load bank controller helps engineers test fuel cells with accuracy, repeatability, and full automation.

Fuel cell testing requires a stable, adjustable, and repeatable load. Without this control, it becomes difficult to compare results or track long-term behaviour. A smart resistive load bank solves this by switching resistor elements in and out to create controlled load steps. The GOcontroll Moduline IV offers a strong base for this kind of setup thanks to its modular design, rugged aluminium enclosure, and wide range of I/O options. Because it allows solid-state contactors, sensors, and logic to work together, it turns a basic resistor bank into a flexible laboratory tool.

The Moduline IV is built on an NXP i.MX 8M Mini processor and includes up to eight module slots. Therefore, developers can combine digital output modules, analog input modules, and specialised modules depending on the test need. The enclosure is CNC-milled from EN-AW5083 aluminium and includes a pressure-equilibrium valve, so it remains reliable in demanding test environments.
Digital outputs can control solid-state relays that switch resistor elements. Meanwhile, analog inputs can monitor voltage, current, and temperature through sensors connected to the installed modules. Because the controller offers four CAN 2.0B interfaces, it also integrates easily with existing fuel cell test benches.

A resistive load bank needs precise control to protect the fuel cell and produce clear test data. With the Moduline IV, resistor stages can be activated in small steps. As a result, engineers can follow a current profile or power curve with high repeatability.
Additionally, the controller processes module inputs locally. This means voltage, current, and temperature readings remain stable even when load changes rapidly. If desired, the logic can limit load when the temperature rises or when voltage approaches a threshold. This improves safety and protects both the load bank and the fuel cell stack.

Closed-loop control is important for advanced tests. The Moduline IV can adjust its outputs based on real-time measurements, allowing it to follow a target load profile automatically.
With this method, the controller can:

• Increase load when current falls

• Reduce load when voltage sags

• Create smooth step profiles

• Run automated sweep tests

• Simulate dynamic operating cycles

Because the logic runs directly on the controller using Linux services, communication delays stay low, and response times stay consistent.

Node-RED is installed by default on the Moduline IV. It gives users an easy way to build dashboards that show real-time voltage, current, and temperature. Even better, engineers can define target curves, test cycles, or load profiles directly from the browser.
Since Node-RED supports MQTT, HTTP, and other communication options, test data can flow to laboratory databases or cloud dashboards. As a result, experiments become easier to track and compare. Logging also helps spot long-term drift in fuel cell performance.

When more complex control is required, the Moduline IV supports MATLAB Simulink. GOcontroll provides a blockset that exposes module I/O, CAN channels, LED indicators, and system states. Engineers can design algorithms, simulate them, and then deploy the compiled model to the controller.
This approach shortens development time because adjustments can be tested quickly. It also keeps the control logic consistent across different setups in the lab.

Fuel cell development changes as new stacks, sensors, or resistors appear. Fortunately, the Moduline IV grows with these needs. New modules can be added without redesigning the system. Additional sensors can be integrated through analog or CAN interfaces.
Because the hardware is rugged and the software flexible, the controller supports long-term laboratory testing. Therefore, researchers can rely on it when exploring new fuel cell concepts or running repeated validation cycles.