Investigations on self-discharge of gel valve-regulated lead–acid batteries

The performance of the self-discharged gel cell has been studied in this work. Although the gel valve-regulated lead–acid (VRLA) batteries were shelved for nearly 3 years, the active mass structure of the positive plate, its resistance and the corrosion layer of the grid are not much affected. On the negative plate, the potential of hydrogen evolution in gel cell is more negative than that in AGM cell. So its self-discharge rate is slower. However, there is still slight accumulation of big PbSO4 crystals. It makes the resistance and overpotential of the self-discharged negative plate increase. But it is not enough to limit the capacity of the gel batteries, which is susceptible to the electrolyte amount. And the capacity of the long self-discharged gel cell can be completely restored by recharging.