Flight Demonstration of a Hybrid Battery/Supercapacitor Energy Storage System in an Earth Orbiting CubeSat

The development and demonstration of a hybrid battery/supercapacitor energy storage system (ESS) onboard the Earth-orbiting CubeSat JPL/CSUNSat1 is described. The ESS is capable of supporting high power pulse currents (>10C-rate) at low temperature (<–40 °C). The primary operational phase of the technology demonstration mission includes the performance characterization of the ESS at various discharge rates (1–15 A) at moderate to low temperatures. The internal resistances obtained from JPL/CSUNSat1 telemetry under battery-only, supercapacitor-only, and hybrid operating modes of the ESS were consistent with ground test data. Despite the loss of telemetry downlinks due to the failure of a memory storage card in the later stages of the mission, ten charge/discharge cycles were performed successfully to validate an impedance-based performance model developed at the Jet Propulsion Laboratory. This flight demonstrates the first use of supercapacitors within a hybrid energy storage subsystem in a space environment.