Modeling of recombinant lead-acid batteries is extended to improve the description of oxygen generation and recombination and to introduce Limited rates of transport of Pb2+ ions on charge as well as hydrogen generation and recombination. A simple, lumped-parameter model is deemed to be adequate to treat system behavior at low rates of charge. The oxygen recombination can be treated as either chemical or electrochemical, and this issue should not be considered to be completely resolved. Model results are compared with experimental results from the literature for cell potential and pressure for several charging rates and extended to the case where the rate is increased or decreased after the battery has been fully charged.