The present invention discloses battery assisted RFID system RF power control implementations that optimize the amount of transmitted power and interference from a reader in relation to the sensitivity of the RFID tags, their ranges from the reader, and the unique physics of the backscatter RFID radio link. Tag transmit power control implementations are also disclosed. These methods enhance system reliability when employing battery assisted RFID tags that operate with sensitive transistor based square law tag receivers and highly sensitive RFID readers intended to take advantage of outstanding tag sensitivity. Further enhancement is achieved via implementation of specialized commands that optimally support the power control operations, otherwise control system interference, and allow maximum usage of high sensitivity in both tags and readers.