Simulink based performance analysis of lead acid batteries with the variation of load current and temperature

Storage device in renewable energy applications plays an important role for efficient operation. For solar PV applications, storage device is an integral part during post sun shine hours to supply power to the load. For Solar Home System (SHS), approximately 60% of the total cost is due to storage battery and the battery needs replacement in every five years or so. If the performance of the battery can be enhanced, not only the cost of energy will come down appreciably but the reliability of the system will improve. Battery is needed in PV system to store the excess energy from the sun and release the power to the system again when it is needed. In other words, to enhance a system performance we have to increase the battery performance. In this paper, the parameters which play important role for optimum performance has been studied. The major two parameters that affect the battery performance are load current and temperature. It has been found that, when the discharge current is high, battery capacity reduces and the vice-versa. Again in case of temperature, when temperature increases more than the rated standard value of 25°C, capacity increases but the life time of the battery decreases. On the other hand, when the ambient temperature goes down, capacity of battery decreases but lifetime of the battery is increased. To analyse the effect of temperature and load current on battery performance, the standard equivalent circuit of battery is considered first and then the equivalent circuit is simulated using Simulink under MATLAB environment.