Be smarter – monitor
your stack.

Monitoring the single cell voltages in fuel cells and electrolysers provides important information for the operation of these systems. Malfunctions are detected at an early stage so that countermeasures can be initiated in time. This significantly extends the service life of the stacks.

Why is Cell Voltage Monitoring important?

Optimize Costs and Efficiency

Beyond its regular operating range, an electrochemically active cell is very vulnerable. The use of low-cost materials, which is necessary to further reduce the costs of the systems, intensifies this effect. If, for example, a hydrogen supply line in a fuel cell vehicle freezes in winter, irreversible corrosion mechanisms occur within the cell, affecting carbon-containing components in particular. The consequence: sooner or later, the entire stack is permanently damaged and fails. Monitoring the fuel cell stack helps to prevent such unintended processes.

The individual cell voltages are a characteristic variable for monitoring. They provide detailed information about the state of the cell stack at any time, thus enabling the operator to react to critical operating conditions in good time. For this reason, cell voltage monitoring systems are an important component of corresponding test benches in the development departments of vehicle manufacturers.

Single Cell Voltages as a Control Variable

In addition, CVM systems are also used in production vehicles when operating strategies for the fuel cell drive are coupled to the individual cell voltages. An example: In winter, if there is a fuel shortage, operation could be switched to electrolysis for a short time using the electrical energy available in the battery. This process generates heat that could be used to thaw a frozen pipe and thus restore normal operating conditions.

CVM systems are also used in the electrolyser to extend the service life of the stack and to control the electrolysis process. Too high cell voltages here mean too much corrosion and thus degradation of the materials.

Common CVM systems monitor the fuel cell stack as a complete system. This has the disadvantage that in the case of a malfunction, no statement can be made about where exactly it occurs in the stack. Single-cell monitoring, on the other hand, makes it possible to precisely localise critical operating states.

CVM briefly explained

Which CVM system is the right one for you?

CVM G5

Four CVM-G5 modules, three of which are plugged together and the front one with the connections for the test leads is slightly offset to illustrate the Lego principle.

Application areas

Use in research and development,
but also in prototypes or very small series

Special features

Single-board solution. High robustness in continuous operation.
Cost advantages due to savings on connectors.

Number of measuring channels

With pure CAN operation up to 600 channels,
500 channels with master module.

CVM G5S

Long circuit board with a connector at the beginning and many smaller plug contacts for connecting the measuring lines from the fuel cell stack.

Application areas

Use in research and development,
but also in prototypes or very small series

Special features

Single-board solution. High robustness in continuous operation.
Cost advantages due to savings on connectors.

Number of measuring channels

With pure CAN operation up to 600 channels,
500 channels with master module.

Are you interested in our CVM solutions?
Let me advise you without obligation.

Wajih Wertateni | T: +49 711 25521-38 |

Wajih Wertateni

How does the cell contacting on the fuel cell work?

The cell contact CVP (Cell Voltage Pickup) is the interface between the cell stack and the CVM, where the potentials are tapped. The pick-up takes place at the bipolar plates and end plates of a stack. The CVM determines all differential voltages between two neighbouring potential taps. Therefore, 101 taps are required for 100 cells, for example.

In view of cell distances of less than 1 millimetre in modern fuel cells, cell contacting represents a particular challenge. Added to this are the different designs of the fuel cell stacks, whose bipolar plates provide different contact surfaces for the potential tap. For this reason, there is no standard contacting unit. A CVP is basically an individual development, tailor-made for the fuel cell stack you are using.

However, there are standardised components of the technology. One example is the contacts, which can be grouped into pin, spring or lug contacts. SMART TESTSOLUTIONS has specialised in spring-loaded contacts. These have advantages in terms of service life in operation. With spring-loaded contacts, a distinction is made between single-sided and double-sided solutions. Which contact type is used depends mainly on the construction of the cell stack.

All CVP solutions are characterised by low space requirements and reliable contact properties, especially in mobile applications. Added to this is a design that makes installation as simple as possible. Every stack is different. We develop the right CVP for you.

Overview of cell contact types on fuel cells.

All CVM data at a glance thanks to web-based user interface

Thanks to the web-based user interface of our CVM systems, the monitored channels can be visualised and recorded massively in parallel, enabling real-time monitoring of the entire stack. This makes effects visible that previously could not be visualised due to the too slow display of traditional test bench software. The significantly higher precision enables development departments and manufacturers to gain much deeper insights into the fuel cell stacks that allow conclusions to be drawn.

The central element of the CVM web interface is a sophisticated dashboard that gives the user an overview of the status of the entire system at a glance. All relevant operating parameters are included.

Voltage values of a Cell Voltage Monitoring system (CVM) are output on the web-based user interface.

As soon as one of them gets out of hand, the user can go into detail with a click.

Another advantage of the web-based user interface is that it makes the entire monitoring system independent of the PC. All that is needed is a terminal device running a browser, while the entire CVM software runs on the master module of the CVM system. Data can be transmitted wirelessly via WLAN. In the future, there will be no need to wire up a laptop for test drives; a simple tablet will be enough to keep an eye on the operating parameters in real time while driving - and with a display that can be switched between day and night mode.

We are your partner for Cell Voltage Monitoring

At SMART TESTSOLUTIONS, we recognised the importance of high-performance energy storage systems and generators early on. More than 20 years ago, we launched our first system for monitoring cell voltages on fuel cells and electrolysers. In the meantime, our CVM systems are used by well-known customers in many countries around the world. You too can benefit from our expertise in the reliable monitoring of fuel cells and accumulators. Please contact us, we will be pleased to advise you.