Proton Exchange Membrane Fuel Cell Transient Load Response

Spaceflight mission profiles may not be limited to constant power loads. It is necessary for the associated power system to support changes in load in addition to being energy dense. H2-O2 proton exchange membrane (PEM) fuel cells can accommodate such requirements without significant current smoothing or additional devices to provide transient power. This testing involved current load step changes to characterize non-flow-through PEM fuel cell response to increasing and decreasing load step changes over a range of 0 to 0.5 A/sq. cm. It was determined that fuel cell output voltage stabilizes within 4 ms with no noticeable steady-state performance degradation, following exposure of the fuel cell to transient loads of up to ~1.5 A/sq. cm. Faster stabilization generally occurred following larger step changes.