NOVELTY - The device (100) has two sensors with the first and second accelerometer and a gyroscope (110). A communication circuit (106) transmits data by two sensors to a mobile device. A component has length, width and thickness where length and width are greater than thickness to create a major surface to abut a body part and zone extends along width for bending of major surface between the first and second section. A battery (140) is mounted to second section to flex relative to a circuit board. A molding houses circuit board, battery and component.    USE - Impact detection device for detecting impact to body portion such as head of user.    ADVANTAGE - The battery protection circuit prevents the battery overvoltage, under-voltage or over-current conditions where the timing devices maintain the real-time clock, communication timing and other microcontroller timing functionality. The impact detection device includes hardware to facilitate power harvesting, wireless power transfer and sensors to sense when the impact detection device is placed on the head or other body portion or uniform of the user. The impact detection devices allows flexibility and conformance to a wide variety of head shapes and sizes while having a mechanical structure that protects the electronic components from mechanical forces, physical impacts, sweat, weather, dirt, debris, dust and other environmental contaminant. The battery arrangement provides the strength to the overall device and strength to the flex zone to ensure the battery leads and solder joints are not stressed and allow an amount of flex to vary according to application. The communication circuit includes universal serial bus (USB) circuitry in order to enable wired communications with an external computing device through the integral USB connector. The impact detection device gathers the heading measurement periodically whenever a walking pattern is detected in order to improve the accuracy and remove erroneous calculations from the heading estimate.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram illustrating an impact detection device.    Impact detection device (100)    Communication circuit (106)    Gyroscope (110)    Antenna (116)    Battery (140)