A reusable battery indicator includes a voltage sensor configured to convert sensed analog characteristics of a battery to digital information; a communication circuit communicatively connected to thevoltage sensor; an antenna operatively coupled to the communication circuit; and a connection mechanism having at least a first connector and a second connector that are electrically connected to thevoltage sensor, the first connector and the second connector being adapted to be removably connected to a first battery terminal and to a second battery terminal, respectively, thereby completing anelectrical circuit between the voltage sensor and the first and second battery terminals when the connection mechanism is coupled to the first battery terminal and to the second battery terminal. Oneor more of the fist connector and the second connector include part of a mechanical lock and key assembly.