The objective of this final thesis project was to study and test a 3,3V LiFePo4 battery in outer space conditions to be able to determine its working range, its limitations and its problems. To do so a measuring set-up to read and estimate the capacity of a battery was built and programmed. Then the LiFePo4 battery was tested at different temperatures between -20°C and 40°C in a vacuum chamber at a pressure under 100 microbars. The results showed that the battery can still operate properly at temperatures as low as -20°C. However a reduction of the capacity at low temperatures was observed: The battery's capacity at -20°C was 62% lower than the one at 20°C. The battery fully recovered its capacity after returning back to the nominal working range (20°C), and its performance barely changed thorough the whole range of temperatures studied.