A method and system for inventorying wireless transponders, specifically referred to as RFID transceiver devices. To provide higher functionality, a microcontroller is used in the RFID, along with a battery, but the clock frequency of the microcontroller is adjusted, based on external input, to minimize battery requirements. The RFID transceiver device includes at least one sensor coupled to the microcontroller. Data from the at least one sensor is stored in non-volatile memory of the microcontroller if the battery is at a predetermined low level, and is read later when the battery is at a higher level.