methods and apparatus , including computer program products , for a power conserving active rfid label . a system for performing radio frequency communications includes a radio frequency identification tag attached to one or more items to be tracked , the rfid tag configured to receive a request and a time interval indicating a time for determining a temperature and a battery voltage , and to adjust the time interval at a time of determining the temperature and the battery voltage if the detected voltage is less than a predetermined voltage , and an interrogator communicatively coupled to one or more antennas to transmit one or more requests to the rfid tag and to receive one or more responses , at least one response including a time , temperature and battery voltage .