Smart Energy Technologies & Energy Storage
Steve Cummings
Director, Sensors Business Unit
Li-ion Tamer
Projections for new installations of energy storage systems continue to grow. This growth can be seen in energy storage targets established by an increasing number of states. However, concerns over the safety of these systems are evidenced by ongoing work on NFPA 855, the release of the UL9540A test method, and number of battery fires in South Korea and the United States. Monitoring and controls play a vital role in the safety of these systems. During this presentation, Li-ion Tamer will report on gas analyses conducting during recent large-scale fire testing using methods specified in UL9540A. New gas monitoring capabilities are being developed to improve detection of faults in the ESS. These methods have also been demonstrated to improve operational safety by preventing fires when the signal is used to electrically isolate the battery prior to thermal runaway. Li-ion Tamer has developed a monitoring system that provides advanced diagnostics to enhance situational awareness of the state of lithium ion battery systems. The off-gas monitor detects electrolyte vented from battery cells with sufficient early warning to stop thermal runaway. Machine learning algorithms have been incorporated in the controls to distinguish environmental anomalies from potential catastrophic events. Early warning provided by the off-gas monitoring system has been demonstrated to detect faults prior to smoke detectors and flammable gas detectors that are commonly used in lithium ion battery installations. Further, third party testing has confirmed the off-gas monitor signal tracks with FTIR gas measurements. Gas analysis is required for propagation testing during certification of many of today’s large-scale lithium ion battery systems such as those required by UL 9540A. While FTIR measurements are not required during field operation of a battery system, installing a network of off-gas monitors into a battery system enables advanced diagnostics to detect off-gas from a single cell within the system. This provides the earliest possible warning of battery failure when compared to other detection systems currently used. Fault detection information supplied by a battery management system can be used in combination with gas detection to diagnose battery health issues prior to an event. Multiple mitigating actions including system shut-down, fire suppression and alarms are possible. Because the gas detection system does not require physical integration with the cells, it offers the potential for redundant safety monitoring, even during transport or storage conditions. Nexceris has monitored the off-gassing characteristics to a range of operational and abuse conditions, including over-temperature, over-charging, and slow leak/pinhole tests in pouch, prismatic, and cylindrical cells. This presentation will provide an overview of the enhanced safety that is enabled through off-gas detection in lithium ion battery systems and how it can add additional layers of safety to protect systems from thermal runaway.