A fuel cell system that employs a super capacitor and battery electrically
coupled in series with each other and in parallel with a fuel cell stack
on a power bus line. As the voltage on the power bus line changes over
the operating requirements of the system, the super capacitor is charged
and discharged over a relatively large voltage swing, such as an 85% SOC
swing. The super capacitor equalizes or voltage matches the voltage
variation on the power bus line as set by the stack voltage to the
voltage of the battery. Therefore, the battery, while providing the
majority of the energy and power during charge and discharge, has a
relatively small defined SOC swing, which acts to maintain the battery
life. The system can also include a diode electrically coupled in
parallel with the super capacitor that provides reverse voltage
protection and electrical power by-pass.