Soft-sensor approach in characterization of VRLA batteries

It is shown in this paper that the state-of-health of a VRLA battery can be tested quickly using a theoretical cell model. A fast testing algorithm-based on direct current-voltage measurements-is used for evaluation of the unobservable processes in electrodes by observable processes. The applied current, terminal voltage and temperature of the surrounding atmosphere are used for testing. The calculation algorithm is tested on experimental data. A good fit between model and measured data is shown for full range of charge-discharge processes including overcharge. The testing algorithm is applied to distinguish between outwardly equal batteries with different backup time and cut-off time. It is shown that difference in morphology of electrodes, thickness of electrodes, and quantity of acid in the Materialswwseparator are the most important parameters in distinguishing between batteries. These parameters can be considered as battery failure indicators and tested by current-voltage measurements. For application in battery testing, the calculation algorithm is optimized for speed.