Faulty battery detecting and locating devices and methods are able to detect and locate a faulty battery cell. The device applies an energy to a sensing member, such as a polymeric tube containing at least two polymer-coated and twisted electric wires. Heat that is generated by a faulty battery triggers an electric communication between the two electric wires by melting at least a portion of the polymer. The resulting change in resistance between the two electric wires is used to detect and locate a faulty battery.