Thermal design and verification of the EOS-AM1 nickel hydrogen batteries

The EOS-AM Spacecraft, which will launch in July 1998, will carry one of the most sophisticated electrical power subsystems (EPS) on any spacecraft to date. The subsystem has been designed to supply the spacecraft with regulated 120 V power for the planned 5 year mission in low Earth orbit, using advanced state-of-the art techniques. A key EPS element is the energy storage system, which is based on two 54 cell 50 amp-hr nickel hydrogen (Ni-H₂) batteries. The thermal design represents Lockheed Martin Astro Space´s first conductively coupled, vertically mounted battery panel design with active thermal control. The thermal environment is crucial to battery performance given the 30% DOD utilization. Battery performance and electrochemical stress are dependent upon the operating temperatures and gradients. The challenge in developing the battery thermal design and details of the thermal design verification, along with thermal balance test results to date, is the subject for this paper