Gates Aerospace Batteries has developed a dedicated reliability function in conjunction with an R & D effort for the NiMH couple. Thus, the preliminary reliability analyses and assessments are being performed in parallel to the NiMH cell design development. The NiMH cell development effort comes from two distinct directions within Gates Energy Products. First, the Gates Energy Products' Sub-C wound commercial NiCd cell is being used for extensive initial investigations. Second, the Gates Aerospace Batteries' mature NiCd Aerospace Product Line provides a close similarity to many of the design features to be used with the NiMH couple. Due to this close similarity, the baseline reliability assessment becomes the Design Trade-Off. The trade-off draws from these two distinct directions and develops an assessment of characteristic differences and from then on analyzes both the primary and secondary effects. The trade-off is categorized into four specific areas. Thereafter, a view into the remaining preliminary analyses and assessments is provided. This includes both the Failure Modes, Effects and Criticality Analysis and the Fault Tree Analysis.