The Li-Ion battery is a very promising technology in terms of mass saving, low thermal dissipation and cost. An advantage is also the capacity to deliver very high power. Li-Ion battery is today perceived by Astrium as the preferred technology for 20 kW and higher power satellites.
The objective of the project is the development and qualification of the battery product. 6p to 9p batteries have been designed for payload power from 8kW to 12 kW which is well in the range of Eurostar 3000/3000LX product. The proposed Li-Ion battery design for Eurostar 3000 satellites is driven by the choice of the cell. The chosen cell is the VES 140 S, which is manufactured by SAFT. This cell is the STENTOR cell and represents the 4th generation of SAFT Li-ion cell. The main advantage of this cell is its high energy-to-weight ratio, its cost and the heritage of a qualification program.
The key issues are related to the qualification of the different items of the battery: 1/ The battery structure with embedded heat-pipes 2/ The cell module which version with 12 cells in parallel will be qualified under environment 3/ The by-pass which is an up-scaled version of the 100 amps STENTOR product shall be developed and qualified for a 430 amperes current 4/ The battery itself which will be qualified as a stand alone equipment
The main advantage is the weight reduction of the battery system due to higher energy-to-weight ratio:The energy-to-weight ratio of Li-Ion is higher than 110 Wh/kg about twice the maximum achieved with NiH2.At battery level, the weight reduction is at least more than 40 %. More than 300 kg could be saved for a 20 kW payload satellite.
Other advantages are also:
These characteristics have a direct impact on the solar panel and radiators sizes.
The Eurostar 3000 battery is an enhanced and versatile design derived from the Eurostar 2000+ flight proven design with the selected capacity to provide the required performance throughout the mission life.
The battery architecture is obtained by serializing 11 cell modules.The following scheme shows an 11s-2p battery: 11 modules in series, 2 cells in parallel. The battery protection is achieved thanks to an overcharge and over-discharge protection associated to each battery and directly sensed by the on board computer hardware reconfiguration logics. The battery is sized up to 80%of DoD.Each Eurostar 3000 battery includes the following redundancies:
The project is in charge of the design and development of the generic product within the range 6-9P.The qualification will be performed on a PFM model of the battery in the 6P version.The cell module will be qualified in an extended version i.e. 12P, and a PFM 6P model will be qualified in parallel.
The design phase of the project is now completed.
The project is currently entering in the qualification phase: