Reference Electrode Measurements, Field Experience, Use and Analysis

For centuries, reference electrodes have been the tool of choice for laboratory electrochemists, in their attempts to obtain a more basic understanding of fundamental electrochemical processes. In the first half of the 20th century, lead antimony stationary batteries were in widespread use for reserve power back-up. Their life-limiting, progressively increasing antimony poisoning effect so dominated the electrochemical depolarization characteristics of these batteries as to allow simple cell voltage and specific gravity measurements to serve as suitable diagnostics of proper float and aging behavior, effectively obviating the need for reference electrode use. With the introduction of low corrosion, low float current, antimony-free lead electrode technology at mid-century, diagnostics became more complex. Individual cell float voltage and specific gravity became virtually meaningless as a diagnostic, useful only to detect shorted cells. Float voltage variations were dominated by the negative electrode, telling the user little if anything about the condition of the life-limiting positive electrode. Reference electrodes were found to be useful in laboratory studies of positive plate polarization and suggested the possible benefit of field studies. Several published papers [1-4] have demonstrated their benefit in the understanding of previously incomprehensible voltage variations. However, little published work [5] has documented their utility as a performance or life-predicting diagnostic. In this paper field reference electrode readings, taken on float, are compared with the results of actual discharge capacity test information, to determine the utility of reference electrode readings in predicting the performance and life of reserve backup lead acid stationary batteries.