One disclosed method involves providing a first device comprising a sensor configured to sense a stimulus experienced by the first device, a controller configured to process data received from the sensor and thereby obtain processed sensor data, a transmitter configured to wirelessly transmit the processed data from the first device to a second device, and a battery configured to supply power to at least the controller and the transmitter. The first device is operated in a first operational mode in which the sensor, the controller, and the transmitter are used at least occasionally to obtain and transmit processed data to the second device. When it is determined that the battery is in a low power condition, the first device is operated in a second operational mode wherein the sensor, controller, and transmitter are not used to obtain and transmit processed sensor data to the second device, but wherein the first device at least occasionally transmits a signal to the second device that indicates a low power condition of the battery.
