Saft Li-ion Batteries Mark Two "Firsts"

The Syracuse IIIA satellite, developed by Saft Batteries, Bagnolet, France, was launched from Europe’s Spaceport in French Guiana. With 3725kg total weight, it was carried into space by an Ariane 5GS launch vehicle (Arianespace, Courcouronnes, France), which uses a variety of Saft specialized spacecraft Ag-Zn and Ni-Cd batteries to support its in-flight systems.

Saft’s lithium-ion battery technology achieved two important firsts with the successful launch of France’s new Syracuse IIIA secure military telecommunications satellite. This is the first time Saft has supplied its rechargeable Li-ion batteries, developed to provide reliable power in a compact, weight-saving package, to Alcatel Alenia Space of Paris. It is also the first-ever application of Li-ion batteries in a military GEO (geosynchronous) satellite.

Syracuse IIIA is the first of two GEO military communication satellites operated by the Defense Procurement Agency within France’s Ministry of Defense, forming the cornerstone of a European military satcom system shared by NATO allies. The Syracuse IIIB is scheduled for launch in 2006.

During a projected 15-year service, the Syracuse III satellites will be “eclipsed” by the Earth around March 21 and September 21 with no direct sunlight for about 22 days on each side of the equinox. Normally relying on solar panels for their electric power during the twice-yearly eclipses, the panels’ batteries must provide sufficient power to ensure the satellite’s continued, uninterrupted service. To meet this demand, Saft has developed a two-pack battery system for both Syracuse IIIA and B. The packs are made up of 12 modules connected in series, each module composed of three VES 140S cells in parallel. The VES cells are manufactured at Saft’s factory in Bordeaux, France, and integrated in the packs and tested at Saft’s facility in Poitiers, France.

The Syracuse III uses the Li-ion battery technology instead of nickel-cadmium (Ni-Cd) or nickel-hydrogen (Ni-H2). Saft’s VES140S Li-ion cells are qualified by both ESA and CNES (Centre National d’Etudes Spatiales) for all satellite applications.

Among the advantages of Li-ion battery technology is the capability to store the same amount of energy as a Ni-H2 battery in a smaller package, a weight saving of around 50%. This enables the satellite operator and manufacturer to carry a larger operational payload to use more of the satellite’s crucial overall mass. The Syracuse III’s lighter Li-ion batteries have enabled additional anti-countermeasure protection to be installed.

The Li-ion technology includes low self-discharge characteristics, allowing the Syracuse III batteries to retain around 98% of their charge even after a month of storage. This simplifies pre-launch management. After the satellite is installed in the launch vehicle, safety and thermal issues associated with battery charging are not present, unlike Ni-H2 batteries that require charging until the last few hours before launch.

Using the weight-saving capability of the Li-ion batteries to increase the operational payload by placing a greater power demand on the satellite power system, the operator normally requires a significant increase in the area of the solar panels. However, the superior charging efficiency of Li-ion enables them to make very efficient use of the charge current supplied by the solar panels, so the increase in panel size is minimized.

This is the first military GEO application for Saft; however, they had already entered service on two commercial GEO satellites and had delivered six more Li-ion batteries for GEO projects launching in 2006.