Silver–silver sulfate reference electrodes for use in lead-acid batteries

Electrochemical properties of silver–silver sulfate reference electrodes for lead-acid batteries are described, and the following possible applications discussed: • Determination of individual capacities of positive and negative plates. • Monitoring individual electrode behavior during deep discharge and cell reversal. • Optimization charge or discharge parameters, by controlling the current such that pre-determined limits of positive or negative half-cell potential are respected. • Observation of acid concentration differences, for example due to acid stratification, by measuring diffusion potentials (concentration-cell voltages). • Detection of defective cells, and defective plate sets, in a string of cells, at the end of their service life. Silver–silver sulfate reference electrodes, permanently installed in lead-acid cells, may be a means to improve battery management, and therewith to improve reliability and service life. In vented batteries, reference electrodes may be used to limit positive plate polarization during charge, or float-charge. Limiting the positive half-cell potential to an upper, pre-set value would permit to keep anodic corrosion as low as possible. During cycling, discharge could be terminated when the half-cell potential of the positive electrode has dropped to a pre-set limit. This would prevent excessive discharge of the positive electrodes, which could result in an improvement of cycle life. In valve-regulated batteries, reference electrodes may be used to adjust float-charge conditions such as to assure sufficient cathodic polarization of the negative electrodes, in order to avoid sulfation. The use of such reference electrodes could be beneficial particularly in multi-cell batteries, with overall voltages above 12 V, operated in a partial-state-of-charge.