Abstract: A battery system includes a battery pack having a plurality of batteries and electronic circuitry for monitoring battery parameters and producing an analog output signal related to the state of the charge in the batteries. An attachment is detachably mounted on the battery pack and produces a display indicating the state of charge in the batteries using the analog output signal from the battery pack. The attachment which includes a bracket and a display unit also serves as connector for connecting the battery pack to the device which is to be powered by the battery pack.