Abstract: For electronic devices that have an electrically conductive surface across a gap from a battery enclosure, the described circuit may be used to detect an anomalous event. The circuit may connect the battery enclosure to ground and may include a switch that operably connects the electrically conductive surface to ground or, upon actuation of the switch, to a portion of the circuit including a resistor. In an anomaly detection mode, the switch is controlled to disconnect the surface from ground and to connect the surface to a resistance measurement channel and a resistor that is connected to the sub-circuit and ground. The system may determine an impedance across the resistor and may use the measured impedance to detect and/or classify an anomalous event.