A battery monitor circuit, systems and methods are disclosed. The battery monitor circuit may have a voltage sensor, a temperature sensor, a processor for receiving a monitored voltage signal from the voltage sensor, for receiving a monitored temperature signal from the temperature sensor, and for generating voltage data and temperature data based on the monitored voltage signal and the monitored temperature signal, an antenna, and a transmitter. The battery monitor circuit may be configured for wirelessly communicating the voltage data and the temperature data to a remote device, via the antenna. In an exemplary embodiment, the battery monitor circuit is located internal to the battery and wired electrically to the battery.