Radiometric measuring device (1, 1', 1"), comprising: - a scintillator, - at least one semiconductor photodiode, wherein the at least one semiconductor photodiode is optically coupled to the scintillator, - a signal evaluation unit which is electrically coupled to the at least one semiconductor photodiode and is designed to determine a measurement variable on the basis of a measurement signal which is generated by means of the at least one semiconductor photodiode, - an interface, wherein the radiometric measuring device (1, 1', 1") is able to be coupled by means of the interface to at least one receiver for the purpose of interchanging data, - wherein the radiometric measuring device (1, 1', 1") is designed to be supplied with electrical energy solely via its interface, - wherein the interface is a current interface, wherein the radiometric measuring device (1, 1', 1") is designed to code the measurement variable by means of a current consumption of the radiometric measuring device (1, 1', 1"), - at least one electrical energy store which can be charged by means of a charging current (I_Lade), and - a charging current controller which is designed to set the charging current (I_Lade) on the basis of the measurement variable, and - at least one adjustable ballast resistor (10, 11) which can be used to control the current consumption (I_Loop) of the radiometric measuring device (1, 1', 1"), - wherein the charging current controller is designed to set a resistance value of the at least one ballast resistor (10, 11) on the basis of the measurement variable such that a current through the at least one ballast resistor (10, 11) is minimum and the charging current (I_Lade) is maximum. - a scintillator, - at least one semiconductor photodiode, wherein the at least one semiconductor photodiode is optically coupled to the scintillator, - a signal evaluation unit which is electrically coupled to the at least one semiconductor photodiode and is designed to determine a measurement variable on the basis of a measurement signal which is generated by means of the at least one semiconductor photodiode, - an interface, wherein the radiometric measuring device (1, 1', 1") is able to be coupled by means of the interface to at least one receiver for the purpose of interchanging data, - wherein the radiometric measuring device (1, 1', 1") is designed to be supplied with electrical energy solely via its interface, - wherein the interface is a current interface, wherein the radiometric measuring device (1, 1', 1") is designed to code the measurement variable by means of a current consumption of the radiometric measuring device (1, 1', 1"), - wherein the radiometric measuring device (1, 1', 1") is designed to be supplied with electrical energy solely via its interface, - wherein the interface is a current interface, wherein the radiometric measuring device (1, 1', 1") is designed to code the measurement variable by means of a current consumption of the radiometric measuring device (1, 1', 1"), - at least one electrical energy store which can be charged by means of a charging current (I_Lade), and - a charging current controller which is designed to set the charging current (I_Lade) on the basis of the measurement variable, and - at least one adjustable ballast resistor (10, 11) which can be used to control the current consumption (I_Loop) of the radiometric measuring device (1, 1', 1"), - wherein the charging current controller is designed to set a resistance value of the at least one ballast resistor (10, 11) on the basis of the measurement variable such that a current through the at least one ballast resistor (10, 11) is minimum and the charging current (I_Lade) is maximum. - wherein the charging current controller is designed to set a resistance value of the at least one ballast resistor (10, 11) on the basis of the measurement variable such that a current through the at least one ballast resistor (10, 11) is minimum and the charging current (I_Lade) is maximum.