Battery performance monitoring by internal ohmic measurements: Application guidelines for stationary batteries. Final report

Various routine inspections and checks offer a general indication of a battery's health and its state of charge. However, none of these routine checks provide definitive information about a battery's actual capacity. Consequently, capacity discharge tests have been and remain the traditional means by which adequate battery discharge tests have been and remain the traditional means by which adequate battery capacity is confirmed. Although technically prudent, the time and expense associated with capacity discharge testing is increasingly at odds with pressures to reduce operating and maintenance budgets. These pressures, in combination with new battery types that cannot be inspected by conventional mans, spurred development efforts for more cost-effective battery test techniques. Resulting advancements in battery monitoring equipment have produced new methods of evaluating battery health and reliability. The results presented here are based on a detailed research program to determine the degree of correlation between capacity and internal ohmic measurements. For each evaluated battery, internal ohmic measurements were recorded for individual cells prior to conducting a capacity discharge test of the battery. The discharge test results were then evaluated with respect to the internal ohmic measurements to determine the degree of correlation between capacity and internal ohmic measurements. The project goal was to obtain the necessary data to demonstrate the technology's value while also providing users with practical information about (1) the relationship between battery capacity and internal ohmic measurements, (2) how to use the test equipment in the field for best results, and (3) suggested guidelines for interpreting the measurements