Battery Temperature Behavior in CubeSats at Low Earth Orbit: From Telemetry to Ground Testing

CubeSats are on a rise as an agile and perspective satellite technology. They are small satellites of a standardized format, using commercial off-the-shelf (COTS) components, which reduces their manufacturing and lunching costs. Batteries are a key part of CubeSats with the task of providing energy whenever needed. Thus, the satellite lifetime is limited (partly) by battery life. Lithium-ion batteries, the state-of-the-art choice for CubeSats, are complex electrochemical systems, with their performance and lifetime behavior strongly influenced by the temperature. Thus, the battery temperature behavior in CubeSats is the focus of this work. Aspects of thermal environment and modelling of CubeSats and batteries are reviewed. Satellite's telemetry is used to derive a temperature data-driven model for low Earth orbit conditions. This model is then convenient for generating test and simulation profiles reflecting realistic conditions that are used throughout the remaining work. A battery management system and its algorithms are one area that must be adapted to such dynamic temperature changes. Thus, a state-of-charge estimation method was developed and demonstrated against a CubeSat temperature profile. Another important area affected by temperature is battery lifetime. A set of calendar and cycling tests were performed and assessed to evaluate a cell's capability to support fiveyears long commercial missions. Finally, as means to directly influence a battery temperature, heaters are commonly used. A model is developed for evaluating the heaters' control, which should ensure better performance and lifetime of batteries in cold cases.