Novel Test Procedure for Assessing Lead–Acid Batteries for Partial-State-of-Charge Duty Using Internal Resistance Charge Acceptance Technique

Battery energy storage systems (BESSs) are often used in partial-state-of-charge (PSOC) operation due to the desire for flexibility of charge and discharge. Lead–acid batteries are a good candidate to be used in battery energy storage due to their safety, recyclability, and long cycle life; however, the correct battery, cell, and regime should be chosen to ensure effective use. Manufacturers rarely publish data on PSOC performance of their batteries. During PSOC use, the charge acceptance of lead–acid batteries reduces both reversibly and, sometimes, irreversibly as the battery is cycled. Typical dynamic charge acceptance tests target the performance required in car batteries and do not adequately demonstrate the charge acceptance expected in BESS use. This paper demonstrates a representative charge acceptance degradation test which far more closely replicates the charge acceptance degradation seen in real-world PSOC BESS use using partial state of charge, coulomb control, and a charge-factor-controlled full charge. Full charges are shown to reverse the internal resistance associated with partial-state-of-charge operation. This is the case in the Leoch lead–carbon cells and 12 V battery tested. This shows that partial-state-of-charge operation degrades the charge acceptance and increases the internal resistance of a lead–acid battery, although with a charge-factor-based full-charge approach, the charge acceptance could be reset to baseline.