# COTS Battery Charge Equalizer for Small Satellite Applications
## 6 Discussion
Consequently, this approach approximates the observed behavior in the tests. However, aside from the effect of temperature, vacuum conditions can also influence the performance of equalization circuitry. In particular, insulation behavior under vacuum conditions must be carefully assessed, as arcing risks or dielectric breakdown between adjacent traces may increase at low pressure if proper spacing is not ensured [38; 39; 40]. Notwithstanding the absence of specific electromagnetic compatibility (EMC) tests, this aspect is critical in satellite design. Both topologies are likely to produce low electromagnetic interference (EMI) due to their low-frequency switching [41]. In future iterations, the incorporation of shielding should be considered for meeting the ECSS-E-ST-20-07C standard of the European Cooperation for Space Standardization (ECSS) [42], which defines the EMC standards that are applicable to space systems. Another type of test that was not conducted in this study was the long-term test. However, the reliability of both topologies in extended missions can be pre-evaluated by analyzing potential failure modes under space conditions. On the one hand, in the DSSCE topology, the balancing process depends on the use of ceramic capacitors and MOSFET switches. As discussed in [43], ceramic capacitors are susceptible to microcracking and capacitance loss when they are subjected to prolonged thermal cycling or mechanical stress, particularly in a vacuum. Furthermore, it has been demonstrated that radiation can induce changes in the parameters of MOSFETs [44; 45; 46], which may consequently affect switching behavior. These effects could lead to a reduction in charge transfer efficiency, slower voltage convergence between cells, and increased power losses due to higher ESR or deficient switching transitions. On the other hand, in the SFCSE topology, apart from the MOSFETs, the flyback transformers are critical components for energy transfer. According to the findings reported in reference [47], radiation exposure can cause variations in core properties. Such degradation may reduce the transformer's ability to transfer energy efficiently between cells and increase switching stress in the control circuitry. Therefore, the appropriate derating of component, shielding, and environmental qualifications is necessary to prevent such degradations from compromising the long-term balancing performance of both circuits. While the present study provided experimental validation under controlled laboratory conditions, it is important to note that it represents an intermediate step toward the eventual development of a flight-qualified system. In future lines of this work, the present study provides the knowledge for the selection of the most suitable topology for a battery management system (BMS) of a 6U CubeSat intended for deep space missions. This system is specially designed to operate under low-temperature conditions and harsh radiation environments of deep space. For that reason, a dedicated PCB (see Figure 10) was developed and will undergo environmental qualification campaigns, including thermal vacuum (TVAC), vibration, and total ionizing dose (TID) tests. The experimental tests will facilitate the evaluation of the system's robustness and reliability under realistic deep space conditions.