A method of operating a battery powered telemetric device configured with a processor, a sensor to measure data to indicate the contents or usage of a product within an asset generating sample data, data storage, at least one battery and a transmitter, includes keeping in the data storage at least one instance of previous data samples represented in a previously transmitted packet, awakening the telemetric device at variable time intervals programmed according to pre-determined user-defined characteristics so that the sensor provides sample data to the data storage to indicate the contents or usage of the product within the asset wherein the telemetric device is otherwise asleep to minimize battery drain, storing all the sample data since the transmission of the previously transmitted packet and the kept at least one instance of previous data samples represented in the previously transmitted packet in the data storage as all the stored sample data, transmitting a packet including representations of the contents or usage of the product within in the asset of all the stored sample data in a manner to limit the number of transmissions to as few as possible unless: the stored sample data indicates changes in the contents or usage of the product within the asset are equal to or exceed a predetermined change value; or there has been no change in the contents or usage of the product within the asset over a prolonged period of time.