Evaluation of conductance and impedance testing on VRLA batteries for the Stenter Operating Companies

Conductance and impedance testing have been proposed in recent years as possible methods of assessing the condition of VRLA (valve regulated Pb-acid) batteries. This paper presents extensive data gathered and analyses it in a number of ways. It includes studying the variance in measurements, correlation with capacity, calculation of 80% cutoff values, box score analysis, investigation of historic trends and intertest-set comparisons. Although conductance and impedance were found to be partly related to capacity, a number of variables and sources of error were identified which significantly affect the accuracy of results. Conductance and impedance testing were found to be a useful aid in identifying good and bad batteries. A number of proposed procedures are suggested for making effective use of these tools