Battery case with thermal insulation for telecommunications outdoor cabinets

This paper describes a thermally insulated case for VRLA batteries for use in outdoor cabinets. The capacities of all kinds of batteries change due to ambient temperature and their capacity decreases as temperature lowers. Therefore, the design capacity must be specified at low temperatures by heating or maintaining the warmth of batteries. NTT studied a VRLA battery case made of styrene. The material is cheap and maintenance is unnecessary. The optimal thickness of the case was found by thermal design and a case was produced based on this. Thermal runaway of batteries in this case did not occur at high temperatures. The authors examined the characteristics of the case by heat cycling tests in a temperature control chamber. In addition to these tests, the case was tested in the field during winter. From the results, the authors established the degree of thermal insulation of the case and how much capacity it maintained. Furthermore, they established the optimal thickness of case design by simulation studies