The exploitation of open circuit voltage parameters and energy recovery after discharge, to decipher the state of health of lead acid batteries

Energy storage devices make up one of the most important components of energy systems. Lead acid batteries are still in use today especially in the less developed world but it is often challenging to depict how good or bad these devices can be once bought from shops. The electrochemical impedance spectroscopy method that has been used for years to determine state of health of batteries has proven to be cumbersome and expensive. In this paper, a simpler SOH determination method for lead acid batteries was presented. Charge and discharge processes were carried out on batteries A, B, C, and D followed by 800 min of Open Circuit Voltage (OCV). After the OCV period, the batteries were again immediately discharged at the same rate to obtain the recovery energy. It was noticed that all the batteries were charged at 2 A for 150 min but the discharge at the same 2A took different time periods for the voltage to reduce to a same cutoff voltage. During the OCV period, battery D and battery B registered quasi constant OCV values while battery A and C registered a considerable decrease in their voltages. For the recovery period, battery B recorded 16.05 min of recovery discharge time while for battery D it recorded 0.8 min. Battery C on its part recorded 0.07 min and battery A barely recorded 0.04 min of recovery discharge time. It was inferred from the work that the higher the degree of self-discharge of a battery, the smaller will be the functional abilities of the battery in terms of the health of the battery. In another note it was discovered that the higher the recovery discharge time of a battery, the greater will the functional abilities of the battery in terms of state of health. Therefore, this simpler method can be used to test a pack of batteries when bought before connecting them to be used.