Processes involving gases in valve-regulated lead/acid batteries

The kinetics of O2 and H2 reactions with the active mass of the plates have been investigated by carrying out open-circuit and overcharge tests on cells and plates coming from commercial valve-regulated lead/acid batteries of different producers. The tests at open circuit showed that the rate of O2 reduction at the negative plates is about four orders of magnitude higher than that of the other four reactions examined (evolution of O2 at positive plates and of H2 at freshly charged negatives, H2 consumption at positive and partially discharged negative plates). H2 leaking through the battery walls, which showed a permselective membrane behaviour, was also considered. Overcharge tests allowed the mathematical model proposed elsewhere to be verified and provided information on the cell behaviour when the overcharge current became equal or lower than the O2-reduction limiting current. The experiments on single plates and on couples (1 positive and 1 negative) sealed in glass vessels showed that the cell construction has a strong influence on the rate of gas-recombination processes.