Battery safety and reliability are closely related and, in some instances, safety may be considered a subset of reliability. However, safety is a concern from manufacture through disposal. Reliability can be approached through three different perspectives: lot reliability, individual cell reliability, and root cause analysis of failed cells. To ensure a quality product, a good reliability management program must be established as part of the manufacturing process. Reliability can be designed into cells through the use of fault tree analysis, while root cause analysis of failed cells is determined by a thorough post mortem analysis of individual failed cells. An existing fault tree can help focus the analysis. Battery safety can be classified as to the different types of hazards according to their effect on personnel and equipment, e.g., physical, chemical, equipment damage, and environmental. To maximize safe performance, each cell and battery should be designed specifically for its intended use. Battery packs must be designed to maintain the safety features designed into individual cells. However, the ultimate responsibility for battery safety lies with the consumer, who must insure proper storage conditions, train personnel in proper handling techniques, and dispose of them in accordance with government regulations.