Method and an arrangement relating to temperature sensing in electric circuitry

摘要

It is shown a method and an apparatus for determining a temperature of a battery pack connected via a single communication line to an electric device. The battery pack and electric device both include control and signaling units capable of exchanging digital signal sequences. The batter pack includes an impedance unit having a temperature dependent impedance value. Signaling between the battery pack and the electric device is followed by a sequence of steps where the control and signaling unit of the battery pack is disconnected from the communication line and the temperature dependent impedance unit is connected to the communication line. Electric current is supplied to the impedance unit via the communication line and a voltage level is measured on the communication line. Then an impedance value is calculated based on the supplied current level and the measured voltage level. An interpretation of the calculated impedance value as a temperature of the battery pack is then performed, followed by disconnection of the temperature dependent impedance unit, and reconnection of the control and signaling unit of the battery pack to the communication line.