End-of-Life Battery Passivation Management System for Small Satellite Constellations in LEO and GEO

One of the main objectives was to work on the definition of the specific conditions required to achieve safe end of mission passivation of Li-ion battery cells and to develop an electrical power management system for small satellites and constellations that would allow battery passivation. The ultimate aim is to provide a solution to meet Space Debris Mitigation requirements for small telecom spacecraft. The project is a multidisciplinary activity addressing the electronic passivation system and the Li-ion battery using COTS 18650 cells. The electronic passivation device is a system designed to safely passivate the satellite battery at the End-of-Life. It is connected between the battery and the PCDU and operates transparently during the nominal life of the satellite. When required, control logic operates redundant relay-based switches to isolate the battery and safely discharge it to a load. At the end of the discharge phase, the battery is galvanically isolated. A full passivation test is performed, emulating a real-world scenario and demonstrating the passivation of the battery behaviour during discharge in representative and worst-case environmental conditions. On the battery side, two types of Li-ion cells have been selected that are suitable for typical LEO and GEO applications. Accelerated and mission representative cycling was performed over the past year. For each cell type, 4 modules 2s2p size have been manufactured to be tested in different test conditions. In addition, abuse tests are performed to study the safety mechanism of the Li-ion cell when exposed to extreme operating conditions such as over-discharge, over-charge, external short-circuit and over-temperature.