BATTERY BASED ON LI-ION AND COTS TECHNOLOGIES: A TEST CASE TO IMPLEMENT HIGH PERFORMANCE, AUTONOMY, AND MODULARITY FOR FUTURE MICROSATELLITES

The paper describes the design, prototype realization, and preliminary tests on an experimental battery module designed taking into account typical microsatellites power requirement, but integrating small capacity terrestrial Li-Ion battery cells, charge/discharge electronics based on COTS integrated circuits and logical electronics able to provide an internal battery management capability. A string of six Li-ion cells (SAFT® prismatic MP17650 – 5.5Ah) able to meet typical microsatellites power requirements has been used (mass of 0.9 Kg, volume of 4.6*10 -4 m 3 , and experimentally verified charge/discharge efficiency of 90%). The battery charge consists in constant current/constant voltage realized by means of the Linear Technology LTC4008 and the battery discharge is performed at constant power, by means of DC-DC step-up conversion based on the Maxim MAX668. Both electronics have experimentally demonstrated efficiencies well above 90%, with associated a mass of 14 g and a volume of 4*10 -6 m 3 . The internal control level is performed using a Microchip PIC18F248, that meet all defined requirements and can be integrated in a control area network to simplify the interfacing with the other satellite system. In order to verify space environment compliance, an analysis on EMI required tests and the possible radiation related failure have been performed.