What makes batteries used in space different?
Batteries used in space undergo extensive research, testing, and development to an even greater degree than batteries used on earth. In such high risk situations, the failure of batteries is extremely dangerous. The process of changing batteries can also be a taxing mission. It took astronauts 6.5-hours to change a set of batteries of the International Space Station. Due to the extreme conditions of space, batteries need to be custom made to fit each mission, environment, and temperature, as well as have the ability to perform its function well in these circumstances, so as not to jeopardize the safety of people involved.
What kind of batteries are used in space?
As on earth, rechargeable lithium-ion batteries are currently the favored choice in space. Using the International Space Station as an example, the batteries used to power the station are recharged with solar energy from the sun and the energy stored is used when it is in orbital darkness — when the station is in the earth’s shadow and not in direct sunlight.
In 2017, NASA began the process of replacing the nickel-hydrogen batteries on the Space Station with lithium-ion ones. Nickel-hydrogen batteries were initially used in space technology because of their long battery life and ability to withstand many charge and discharge cycles without significant degradation. However, the extra process of battery conditioning was necessary in order to combat the cells’ “battery memory” which sees a battery lose a portion of its capacity if not fully charged and discharged every cycle.
Lithium-ion batteries were a welcomed upgrade to the 20-year old station. Being more light-weight and energy-efficient, just one lithium-ion battery was needed to replace two nickel-hydrogen ones, a vast upgrade in energy and volume densities. The new batteries are also not susceptible to battery memory, negating the need for conditioning. Nonetheless, each type of battery still has its own drawbacks. Lithium-ion cells are more sensitive to overcharging, overheating, and cases of thermal runaway. Thus, battery testing is crucial and any battery used in space must be subjected to rigorous testing before being certified safe for use in space.
The difference between batteries used in space and common batteries
The lithium-ion batteries currently on the Space Station are extremely heavy-duty and made to last much longer than the average battery used in everyday life. The average rechargeable lithium-ion battery found in common appliances such as cell phones lasts about three to five years, or 500-1000 complete charge cycles; the batteries used in electric vehicles are made to last eight to ten years and a few thousand charge cycles; batteries on the Space Station have been designed to last for ten years and 60,000 lifecycles. The standards for batteries is space in much higher. Strict and comprehensive testing is needed to meet these requirements.
Testing batteries made for space
Since batteries release energy through chemical reactions, the environment in which they operate affects their performance. Because of the extreme conditions of space, batteries need to undergo intense testing under a number of different conditions in order to be certified for use.
For instance, batteries need to be tested under vacuum conditions. Research has found that overcharging the battery did not lead to thermal runaway, whereas an external short circuit test did. These results are the exact opposite of the same tests being performed in ambient pressure environments. Batteries are also often put under abuse tests to understand the worst case scenarios as well as the steps necessary to avoid these situations and properly manage the battery.
Moreover, based on the mission, batteries need to function in circumstances not encountered on earth. For example, some missions require batteries to work in extreme low temperatures of -20 to -100°C. Temperature greatly affects the rate of charge and discharge, thus it has to be made certain that the batteries can function at these temperatures.
As with any battery, overheating and overcharging are huge safety concerns. Proper battery management systems and [battery testing equipment] must be used in order to ensure the safety and stability of a battery, most especially in space where the stakes are high. In these circumstances, precise and reliable test equipment is critical.
Space technology on earth
While uses of such a heavy duty battery as used in space is rarely necessary on earth, the innovations made in space technology have a trickle down effect, eventually capable of being used in everyday life without us even realizing its origin. Cameras now commonly found in mobile phones, DSLR cameras, and other portable devices can be traced back to NASA scientist Eric Fossum, whose work in miniaturizing cameras for interplanetary missions made is possible for cell phones to have good quality cameras.
Thus, any innovation from research on space technology and batteries used could one day help and benefit the masses, improving the batteries and appliances we use in everyday life.
Continuously improving and innovating at the battery testing level is also crucial to the research and development of batteries. When testing equipment can keep up with materials research and dynamic charge/discharge profiles to mimic how appliances and technologies would use batteries, better predictions and assessments can be made. If the heavy duty [battery technology of space] is one day incorporated into everyday technology, commercial battery testing equipment should be able to meet this demand.