Lithium-ion rechargeable batteries have a high energy density, thus, in order to prevent the batteries from overheating or exploding due to overcharging, NEC TOKIN has also developed a battery pack with terminals and case applied to the cells, while protection circuits and elements are installed to cells. As performance required for mobile devices is maximized, we respond to customer demands as a custom product for optimal cell selection and battery pack design in terms of size, weight, drive time and other factors. We are also introducing the cell as a product lineup in our company catalog. The protection circuits and elements are designed to protect the cell from bursting or catching on fire at overcharging, over-discharging and other abnormalities thus providing a double and triple layer of protection functions. For the protection circuits, protection ICs, charging & discharging control FETs, condensers, resistors, thermistors and other components are normally integrated on one print board, and connected to a PTC, a type of thermistor. (Protection circuit system) For types using manganese materials on the positive electrode, it uses characteristics that counteract overcharging and over-current and provide thermal stability, and adjusts the battery protection functions of the main device unit, thus it is compatible with PTCs, thermal fuses, resistors and other protection elements. (Simple protection system) The terminals are lead wire (with connector) and terminal types (contact type), while component selection and design respond to customer demands. The cases come in hard, semi-hard and label-wrapped types which also respond to customer demands.