Year
1993
Abstract
Lithium batteries are often the power source of choice for safeguards instrumentation. However, these batteries do not, in general, enjoy a particularly good reputation for reliability. This paper examines ways to reduce or even eliminate the risk of putting a \"bad\" cell into service. The conclusion is presented that the expected number of field failures of lithium batteries may be reduced by several orders of magnitude by a combination of proper lot qualification of cells, measurement and testing, record keeping, and system design. Overviews of both non-destructive and destructive testing are presented. Tests to verify manufacturer's claimed capacities, scenarios for \"grading\" of batteries and examples of lot qualification are discussed. The principle of redundancy through the utilization of dual power systems is discussed. Recommended practices for reliability improvement are presented to include: Pre-Aging,Grading,Capacity Testing, Lot Sampling. Design methods are presented which reduce the consequences of a failed cell. The paper is intended to be used as a guide towards achieving best field performance from instrumentation, with emphasis on principles rather than specifics.