Hybrid ultracapacitor based power supplies (HPS) enable high power density well beyond traditional capabilities of bulk energy storage such as Li-Ion batteries. The targeted application that this proposal will focus on is a high power (> 100W) HPS for integration into CubeSats. The CubeSat platform was chosen for its inherent size and weight restrictions but as a relatively low cost and standardized platform for this new technology. Future development of ultracapacitor based HPS systems will leverage the size, weight, and performance benefits demonstrated on the CubeSat platform for expansion into larger more powerful systems. Beyond CubeSats, ultracapacitor based power systems enable any platform that incorporates low power energy generation to reduce the mass and volume of its energy storage while improving power bus regulation and system efficiency. For example, RTG, flywheel, and photovoltaic platforms typically include battery packs for storage and high power delivery that can be made smaller and lighter while enabling substantially higher power delivery. Furthermore, the use of ultracapacitor systems enable efficient point of load (POL) generation and power delivery, reducing system complexity, wiring harness size, and enabling new sensing architectures. Additional applications include weather balloon communication and sensing, extravehicular activity (EVA) suits, satellite load deployment, vehicle separation stages, and many more. Hybrid ultra-capacitor power systems find potential applications in many fields where high power density is critical for operation. FastCAP's ruggedized system designs and large temperature range find immediate application in NASA applications as well as other applications within military, automotive, and aerospace industries. FastCAP's hybrid technology is of interest to the military to reduce the size and weight of existing battery storage while improving power density. For example, assisted human exo-skeletons are wearable mobile systems intended to assist a soldier in physical tasks that would other be too difficult to complete without machinery. High power density power systems are required in order to be light enough be worn while powerful enough to power exoskeleton motors. Other uses included compact missile power systems where fast deployment of loads or motor actuation is required in a very small, ruggedized form factor. Additionally, micro-grid technology often integral to special operations units, can be benefitted for mass and volume reduction while supporting the array of communication, sensing, and life support systems typically power by solar panels and lithium batteries. Finally, the aerospace and automotive industries are primarily concerned with mass reduction, safety, and cost reduction. All of these come with reducing the amount of lithium required for storage, shipping, and integration into power systems in planes and automotive vehicles.