MODELING OF LOCAL CONDITIONS IN FLOODED LEAD ACID BATTERIES IN PHOTOVOLTAIC SYSTEMS/

A model is set up for a time-dependent description of currents, polari zations, state-of-charge and acid concentration with high spatial reso lution in a flooded lead/acid battery. The detailed description of all relevant parameters for a battery under real operating conditions all ows the use of results obtained under well-characterized laboratory co nditions for different ageing effects. Models of acid stratification, vertical current distribution in the electrode, and description of pol arizations, concentrations and state-of-charge in the porous electrode s are necessary for any ageing model. First results show the very seve re conditions for the lower part of the electrode under typical operat ing conditions in photovoltaic power supply systems. The work aims at a quantitative ageing model for batteries in such systems.