Electronic circuit for charging a rechargeable battery of a blower filter unit, which can be supplied with energy by an external electrical energy source, designed in such a way that a) the electronic circuit has a first charging connection, which can be connected to a positive pole of the rechargeable battery via a first electrical line, and a second charging connection, which can be connected to a negative pole of the rechargeable battery via a second electrical line, b) a plurality of series-connected parallel circuits, each composed of a resistor element designed as a diode and a switch element, are arranged in the first line or in the second line, wherein each diode is configured in such a way that at least some of the associated charging current flows through the diode in the forward direction during charging of the rechargeable battery, c) the electrical circuit comprises a measurement apparatus, which is designed to measure a charging current through one of the lines (4, 6) or a voltage between the charging connections (3, 5), d) at least one control electronics system is provided between the switching elements and the measurement apparatus, said control electronics system being designed to receive a measurement signal of the measurement apparatus and to monitor the flow of current through the lines (4, 6), e) the control electronics system is designed in such a way that it switches the switching elements in a high-impedance manner or to open in the absence of a charging current, and f) the control electronics system is designed in such a way that it switches the switching elements in a low-impedance manner or to closed in the presence of a charging current. a) the electronic circuit has a first charging connection, which can be connected to a positive pole of the rechargeable battery via a first electrical line, and a second charging connection, which can be connected to a negative pole of the rechargeable battery via a second electrical line, b) a plurality of series-connected parallel circuits, each composed of a resistor element designed as a diode and a switch element, are arranged in the first line or in the second line, wherein each diode is configured in such a way that at least some of the associated charging current flows through the diode in the forward direction during charging of the rechargeable battery, c) the electrical circuit comprises a measurement apparatus, which is designed to measure a charging current through one of the lines (4, 6) or a voltage between the charging connections (3, 5), d) at least one control electronics system is provided between the switching elements and the measurement apparatus, said control electronics system being designed to receive a measurement signal of the measurement apparatus and to monitor the flow of current through the lines (4, 6), e) the control electronics system is designed in such a way that it switches the switching elements in a high-impedance manner or to open in the absence of a charging current, and f) the control electronics system is designed in such a way that it switches the switching elements in a low-impedance manner or to closed in the presence of a charging current.