Research of critical causes and improvement of energy storage system reliability in power electronic applications

In order to prevent the critical failures in lead acid batteries, the authors propose a new multistep current charge profile based on mathematical methods to calculate the charge current for each step according to the battery voltage variations and state of charge. The energy management system is developed in order to avoid the deep discharge that causes stratification of electrolyte, sulfating and deterioration of active mass. In addition, the electrodes corrosion and gassing phenomena are prevented by adopting a suitable charge cycle. In this paper, the causal tree analysis is used to identify the critical failure modes of battery and their causes in different applications such as uninterruptible power supply, renewable energy and hybrid electric vehicle. The identification of the degradation causes allows properly proposes some recommendations in order to extend the battery lifetime by adding suitable additives in the manufacturing process and adopting an appropriate charge cycle. The experimental result of the multistep current profile is realized with lead acid battery 90 Ah to investigate their efficiency to ensure the maximum battery reliability. This current profile avoids the corrosion phenomenon generated by overcharge and the sulfating phenomenon caused by an incomplete charge with a charging time depends on the number of the chosen step. Therefore, the multistep current profile is a suitable charge cycle that preserves the battery capacity and increases its lifetime.