Evaluating the state-of-health of flooded and valve-regulated lead/acid batteries. A comparison of conductance testing with traditional methods

• Published in: Journal of power sources Vol. 46; no. 2; pp. 391 - 415
• Main Authors: O. Feder, David, J. Hlavac, Mark, Koster, Wim
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1993
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/0378-7753(93)90035-Y

In a previous series of studies, field and laboratory examinations were made of the relationship of both traditional cell-testing parameters and conductance testing with actual capacity testing for approximately 500 valve-regulated lead/acid (VRLA) cells of various sizes and designs, and in various applications. It was concluded that a significant number of VRLA cells had suffered premature capacity loss, that was not detected satisfactorily by the individual cell float-voltage or by specific-gravity (calculated) measurements. In contrast, the data showed a high degree of correlation between cell capacity and cell conductance. This study provides additional evidence of the extent of premature capacity degradation of VRLA cells, and includes cells of newer designs. It quantifies, more explicitly, the inability of cell float-voltages or specific gravity to provide early warning of these significant failures in capacity. It provides additional data that demonstrate the high degree of correlation between conductance and capacity, and presents striking evidence of the ability of conductance testing to provide early warning of premature capacity failure of VRLA cells. Additional data are given on teardown postmortum analyses of a series of cells that exhibit a wide range of measured capacities. Although the established failure modes among these cells are significantly varied, it is extremely encouraging to report that cell performance is accurately predicted by the conductance values obtained. A report is also given of the results of initial tests of conductance/capacity relationships in flooded lead/acid cells, i.e., of the type used by both electric power utilities and telecommunications organizations to provide stand-by reserve power. The accuracy of conductance data to predict, correctly, cell capacity behaviour is contrasted with predictions that result from the conventional test parameters of cell float-voltages and measured specific gravities. Again, with flooded cells, the data indicate a significantly improved capability to detect low-capacity cells, based on conductance, than would be obtained from either cell float-voltage or specific-gravity measurements.