The invention provides a system and battery including a state-of-charge indicator (SOCI) to monitor and display the amount of charge within the battery. The SOCI is capable of operating in a hibernate mode, an active mode, and/or a sleep mode. The battery may be manufactured, shipped and/or stored with the SOCI operating in a power-saving hibernate mode. The SOCI may exit the hibernate mode and begin operating in active mode if a physical key connected to the battery is removed. In addition, the SOCI may operate in a sleep mode while the battery is not being used to conserve power. Furthermore, the invention provides a method of making a battery including a SOCI to monitor and display the state of charge of the battery.