Abstract:

The relationship between open circuit voltage and cumulative discharge capacity of lead-acid battery is the basis of lead-acid battery model, which has significant effect for the study of electrochemical reaction and mass transfer process in the battery. The data of voltage and accumulated discharge capacity during 30 times discharge processes were measured by constant current discharge method. A method to obtain open circuit voltage based on fitting and extrapolating with experimental data is proposed, which is more reasonable than the traditional one. A piecewise linear relation model for open circuit voltage and cumulative discharge capacity is derived which is based on the assumption that the rate of electrochemical reaction is in direct proportion to the square of the electrolyte concentration. Then the segmented nodes of the model are optimized by genetic algorithm before parameters are related, the results are in good agreement with the experimental data. It provides theoretical support for the study of reaction mechanism in lead-acid battery.

Key words: state of charge, lead-acid battery, open circuit voltage, cumulative discharge capacity