Performance Evaluation and Commissioning of a 110V, 440AH VRLA Battery Bank at Dagachhu Hydropower Plant

Abstract

Valve-Regulated Lead Acid (VRLA) batteries are important components in hydropower plants, as they provide the critical DC supply for auxiliary, protection, and emergency systems. Despite their widespread use, the reliability of these battery banks is often compromised by a lack of systematic testing after installation, leaving operators without precise data on actual capacity, internal resistance, or real-world degradation rates. Furthermore, improper commissioning, such as placing new batteries on float charge without pre-commissioning inspections, can significantly shorten a battery’s operational lifespan. This study establishes a baseline performance evaluation for a newly installed 110 V, 440 Ah VRLA battery bank at the Dagachhu Hydropower Plant (DHP) to ensure operational readiness. Adhering to IEEE Std. 450-2010 and IEEE Std. 1188-2005, the methodology involved three regulated charging and discharging cycles combined with precise impedance measurements using diagnostic tools such as the TORKEL 860 and Megger BITE3. The obtained results demonstrated a progressive improvement in the battery bank’s health by the second cycle, and the measured capacity achieved the full rated capacity by the third cycle. Complementing this capacity growth or improvement, the cell impedance measurements were taken, as the impedance values are usually correlated to the capacity. The quantitative impedance analysis revealed an average reduction in internal impedance of 11.27% before discharge and 13.98% post-discharge between the first and third cycles. This study validates the successful initiation of the battery bank and provides the necessary baseline data, ultimately enhancing the reliability and safety of the plant’s auxiliary power systems.