BACKGROUND

In recent years, following several spacecraft battery anomalies, it was determined that managing the operational factors of the NASA flight NiCd rechargeable battery was very important in order to maintain spaceflight battery nominal performance. Hence, NASA had to call upon JPL to initiate studies and analysis in order to establish an operations management protocol for these batteries. The optimization of existing flight battery operational performance was viewed as something new for Taguchi Methods of application.

PROCESS

The evaluation, qualification and operations management of secondary batteries for NASA space vehicles are involved and constitute a very lengthy process. Rechargeable battery evaluation requires tens or even hundreds of cycles. Testing for the performance effects of these parameters could be a never-ending task. In this particular case, a full factorial with five factors at four levels would have required 1024 experiments. Since each experiment must be performed at the given levels for 60 cycles (approximately four days), a total of 4096 days or 11.2 years of experimentation would have been required had this approach been adopted. With Taguchi Methods, the best results were obtained with only 16 experiments. Because of time constraints, the dynamic S/N ratio approach could not be used. In this experiment, the S/N ratio in the case of "nominal the best" approach was used.

BENEFITS

• The application of Taguchi Methods resulted in cost savings of over 400% and over 300% reduction in experimental time...