Theory for the Lead–Acid Battery Interface
The Lead–Acid Battery Interface uses concentrated electrolyte theory to model electrolyte transport and electrodes of changing porosity in a lead-acid battery. The physics interface solves for the electrolyte salt concentration, electrode porosities, electrolyte potential, and electrode potential. The notations for these dependent variables are the following:
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 cl, dissociated salt concentration of electrolyte, here H+/HSO4−,
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 ε, porosity (volume fraction of liquid electrolyte) of the porous electrodes,
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 ϕl, electrolyte potential, and
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 ϕs, electric potential in the electrodes.
A lead–acid cell typically consists of five parts: a positive porous electrode (PbO2), a reservoir of electrolyte, a porous separator, a negative porous electrode (Pb), and two current collectors/feeders in contact with the positive porous electrode and negative porous electrode, respectively.
In this section:
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The Electrode Reactions Equations
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Electrode Kinetics and Active Available Surface Areas
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Electrode Charge Transport Equations
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Electrolyte Transport Equations