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Objectives
This project consists of life testing VES180SA cell modules in accelerated GEO cycling with PPS. It will include ASTRIUM & TAS as partners for the definition of the tests conditions representative of their missions, and ESBTC as the provider of External Service for life tests execution from 2013 to 2022 (30 seasons mission + 15 seasons margin). In addition, these life tests will cover the need of electric propulsion during the transfer phase for full electric satellite applications.
Background
In 2003, the ARTES-8 contract no. 16928 / 2002 / F / WE started to qualify the VES180 as a next generation cell. In August 2009, Optus-D3 was the first satellite to be launched with VES180SA, opening the way to many new contracts for Saft on the export market. Nowadays, the VES180SA cell is used by many primes worldwide.
Figure1: Picture of theVES180SA Li-ion cell
PPS (Plasmic Propulsion Systems) are more and more common today onboard geostationary satellites. In particular, recent proposals made by EU primes indicate that PPS is adequate for many GEO mission cases, and the vast majority of their customers is retaining it.
The actuation of PPS results in additional cycling of the battery, with up to one cycle per day at 30% DoD inducing higher fading. The need for an appropriate demonstration by life-test was anticipated and addressed by Saft’s T7 life-tests, performed by ESTEC in the frame of ARTES contract.
Present situation
T7 was performed taking into account severe conditions with an end of charge voltage of 4.1V, at 20°C and depth of discharge equal to 20% in equinox season and 30% in solstice. In these conditions, T7 exhibits a trend leading to 14.4% fading at 15 years.
However T7 conditions were too stringent compared to the current conditions of use aboard Alpha Bus, Eurostar 3000 and Spacebus-4000 platforms. Indeed, their conditions are much more favourable in term of voltage (slightly below 4,1V in equinox) with maximum PPS DoD equal to 10-15% in equinox season and 20-25% in solstice. In addition, charge ratio has been adapted to suit Astrium and TAS conditions.
Saft estimates that such conditions will lead to a total fading in the range 9-11% at 15 years on a VES180SA battery.
Description of the activity
The aim of the activity is to manufacture two 3P modules with VES180SA-Alternate cells (LF3) and then perform one accelerated life-test under Astrium conditions and another one under TAS conditions.
Figure 2: Picture of theVES180SA Li-ion equipped cell modules
Astrium, TAS and Saft have jointly worked to cover worst case mission with PPS, on Eurostar 3000, Alpha Bus and Spacebus-4000, in term of power demand and cycling.
Challenges
The main challenge is to define life tests conditions as representative as possible of the mission in covering future PPS and full electric satellites needs.
Plan
The partners will combine their effort according to the following scheme:
| Task | Scope | Responsibility (contribution of total endeavor) |
| Task 1 | Kick-Off (KO) Preparation | – Saft: VES180SA Cells selection, initial life test plan |
| – ASTRIUM & TAS: contribution to tests plan issuance wrt. their applications | ||
| Task 2 | Tests Readiness Review (TRR) preparation | – Saft: Module manufacturing and initial characterization tests |
| – ESTEC/ESBTC: Life tests set-up and tests procedures | ||
| – ASTRIUM & TAS: contribution to TRR process | ||
| Task 3 | Life tests execution and reporting | – ESTEC/ESBTC: o Life tests executions o Supply of periodic check-up reports (every 2 seasons) |
| – Saft: o Periodic Analysis of tests results and compilation in overall VES180SA life tests reports periodically ; |
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| – ASTRIUM & TAS: contribution to life tests follow-up and tests conditions adaptation if needed |
Table 1: Respective responsibilities of the partners
Current Status
TRR for start of life tests was held beginning of Sept 2013.