Reusable battery indicator with electrical lock and key

A battery indicator comprising:

• a voltage sensor, the voltage sensor being configured to convert sensed characteristics of a battery to digital information;
• a communication circuit, the communication circuit being communicatively connected to the voltage sensor;
• an antenna operatively coupled to the communication circuit;
• a connection mechanism having a first connector and a second connector that are electrically connected to the voltage 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 providing an electrical connection between the voltage sensor and the first and second battery terminals;
• and
• an electrical key component that is configured to enable functionality of the communication circuit when in the presence of an electrical lock component;
• wherein the electrical key component comprises a split antenna matching network, an optical sensor, a capacitive coupling connection, or a Hall-effect sensor.