What balances the charge in a lead-acid battery?

In a lead-acid battery, the charge balance is maintained through the chemical reactions between lead dioxide (PbO2), sponge lead (Pb), and sulfuric acid (H2SO4) during discharge and charge cycles. When the battery discharges, lead dioxide and sponge lead react with sulfuric acid to produce lead sulfate (PbSO4) and water, releasing electrical energy. During charging, this process is reversed, converting lead sulfate back into lead dioxide and sponge lead while regenerating sulfuric acid. This cycle ensures the charge balance is maintained throughout the battery's operation.