Electrical Circuit And Method For Charging A Secondary Battery

An electrical circuit for charging a secondary battery having a dc-converter, the dc-converter comprising

• an input connector, connectable to an input dc voltage,
• an output connector, connectable to the positive terminal of the secondary battery for applying a charging current to the secondary battery and
• a voltage feedback connector for sensing a feedback voltage, wherein the dc-converter is adapted to regulate the output voltage by adjusting the output current at the output connector depending on the sensed feedback voltage;
• and a feedback-sub-circuit connected to the output connector and to the voltage feedback connector of the dc-converter, wherein
• the feedback-sub-circuit comprises a positive temperature coefficient resistor connectable in series to the secondary battery, wherein the positive temperature coefficient resistor is disposed in the electrical circuit between the negative terminal of the secondary battery and a ground connector of the dc-converter such that an increasing resistance of the positive temperature coefficient resistor results in an increasing voltage at the voltage feedback connector.