Lithium-ion cell modules for its Eurostar platforms
Lithium-ion cell modules for its Eurostar platforms
Keywords: Aircraft components, Aerospace industry
Saft has signed a LTA with EADS Astrium for the exclusive supply of the high-technology, on-board, lithium-ion (Li-ion) cell modules for all Astrium Eurostar GEO (Geosynchronous Earth Orbit) platforms for communications satellites over the next four years. This LTA results from the close cooperation between Saft and EADS Astrium over the last decade which has led to the qualification of a complete product range and successful in orbit operation of the first lithium-ion batteries for GEO applications.
The rechargeable Saft Li-ion cell modules, based on high-energy VES140 and VES180 cells, will provide a compact, weight-saving source of back-up power to ensure continuous, reliable operation of the satellites at times when their solar panels are in eclipse.
The first three contracts already signed under this LTA are worth a total of around €2,5 million.
Normally, the on-board electronic systems on a GEO satellite rely on solar panels for their electric power. However, the nature of their orbit means that during the twice-yearly equinoxes, around March 21 and September 21, the panels will be “eclipsed” by the Earth, with no direct sunlight. During these periods of around 22 days on each side of the equinox, the on-board batteries have to fulfill the demanding role of providing sufficient power to ensure the satellite's continued, uninterrupted operation, over a service life of up to 15 years.
Rather than using nickel-cadmium (Ni-Cd) or nickel-hydrogen (Ni-H2) battery systems to provide this on-board power, EADS Astrium has selected Saft's Li-ion battery technology. Saft VES140S cells are qualified by both ESA (European Space Agency) and CNES (Centre National d'Etudes Spatiales) for all satellite applications. They have already entered in-flight service on two commercial and one military GEO satellites, and a further six Li-ion batteries have been delivered by Saft for GEO projects to be launched in 2006. The qualification of the Saft VES 180SA is close to be completed and will meet the need of next generation programs.
One of the main advantages claimed of Li-ion battery technology is its capability to store the same amount of energy as an Ni-H2 battery in a smaller package, offering a weight saving of around 50 percent. This will enable both EADS Astrium and the satellite operator to utilise more of the satellite's crucial overall mass to carry a larger operational payload.
A further benefit of Li-ion technology is said to be its low self-discharge characteristics, which enable the batteries to retain around 98 percent of their charge even after a year of storage. So, they do not need recharging while the satellite is on the launch pad, unlike Ni-H2 batteries that require charging until the last few hours before launch. In other words, pre- launch management is simplified, as, once the satellite is installed in the launch vehicle, safety and thermal issues associated with battery charging are suppressed.
By using the weight-saving capability of the Li-ion batteries to increase the operational payload, the operator places a consequently greater demand on the satellite power system. The superior charging efficiency of Li-ion enables them to make very efficient use of the charge current supplied by the solar panels.
The VES140 and VES180 cells are manufactured in Saft's industrial factory in Bordeaux, France and will be integrated into the EADS Astrium cell modules and tested at Saft's facility in Poitiers, France. Modules will be integrated in complete batteries by EADS Astrium in Toulouse, France.
For further information, contact: Saft Specialty Battery Group. Tel: +33 1 49 93 19 18, e-mail: antoine.brenier@saftbatteries.com
