Battery evaluation methods and results for stationary applications

Evaluation of flooded lead-acid, valve regulated lead-acid (VRLA), and advanced batteries is being performed in the power sources testing labs at Sandia National Laboratories (SNL). These independent, objective tests using computer-controlled testers capable of simulating application-specific test regimes provide critical data for the assessment of the status of these technologies. Several different charge/discharge cycling regimes are performed. Constant current and constant power discharge tests are conducted to verify capacity and measure degradation. A utility test is imposed on some units which consists of partial depths of discharge (pulsed constant power) cycles simulating a frequency regulation operating mode, with a periodic complete discharge simulating a spinning reserve test. This test profile was developed and scaled based on operating information from the Puerto Rico Electric Power Authority (PREPA) 20 MW battery energy storage system. Another test conducted at SNL is a photovoltaic battery life cycle test, which is a partial depth of discharge test (constant current) with infrequent complete recharges that simulates the operation of renewable energy systems. This test profile provides renewable system designers battery performance data representative conditions. This paper describes the results of these tests to date, and include analysis and conclusions.