A Novel Approach Using High Charging Voltage for the Restoration of Discarded Lead Acid Batteries

A lead acid battery is an old renewable battery that is usually discharged to deliver a high surge current to ignite a petrol-based engine. Nowadays, there are different improved versions of lead acid batteries that can deliver high energy densities with low maintenance costs. As the batteries are charged and discharged repeatedly over time, the amount of lead sulfate across the electrode plates grows, reducing the total surface areas of the plates and, thus, the rate of ionization between the electrolyte and the plate surfaces. The batteries then eventually come to the end of their service lives. Even with the improved versions, lead acid batteries are usually discarded at their retirement. However, if the retired batteries can be used for other purposes, the circular economy of the batteries can be improved significantly. It is therefore necessary to study the physical characteristics of the retired batteries and explore means of improving their charging and discharging capabilities. This paper presents research on improving the storage capability of retired lead acid batteries by applying different charging voltages across them. The results show that the electrode plates of the retired batteries become porous when a high charging voltage is applied, hence increasing the total surface area of the plate surfaces. The storage capability of the batteries is improved because the accumulated lead sulfate is removed from the electrode plates by the high charging voltage. As a result, the rate of ionization is increased, hence restoring the storing capability of the retired batteries to up to 71–89% of the original capacity rating