What it is

Fuel cells are chemical reactors that transform hydrogen and oxygen to electric energy and heat. A single fuel cell produces its electricity at a voltage of less than one Volt. So, for practical applications fuel cells are connected or stacked in series to achieve high voltages. Generally, the gasses are supplied to the cells in a parallel arrangement.

A consequence of this setup is that the gas supply to the individual cells of a stack can differ while the current flowing through them is identical. This can result into large differences in cell voltages within one stack. When a cell produces current at a low voltage (compared to the other cells in the stack), this is a clear indication something is wrong in the operation of this cell.

Since the efficiency of a fuel cell is measured by the cell voltage, cells are always operated at the highest possible voltage. Consequently any deviation from this optimal situation, e.g., due to a failing component or control, will be translated to a lowering of cell voltages. Consequently, cell voltages indicate the correct and safe operation of a fuel cell stack.

The main problem, however, in measuring individual cell voltages is the presence of a common mode DC voltage that is different for every cell and changes in time. Of course solutions exist to cope with this, but they tend to be expensive. CellSense is a cell voltage monitoring device that can measure voltages of individual cells providing a solution to both problems. As a consequence it is well suited for monitoring commercial stacks and integration in control systems.

Many CVMs have been delivered and are in daily operation proving the reliability and robustness of the technology. Check out our references.

Technology used in CellSense is protected by a patent.