A battery charging method and system with a temperature-compensated charge profile requires that, during a \u2018bulk stage\u2019, a regulated constant charge current is provided to the battery until the voltage across it increases to a predetermined \u2018absorption stage voltage limit\u2019, at which time charging transitions to an \u2018absorption stage\u2019. The apparatus is constructed of inexpensive elements, including a single two-way valve which renders the apparatus very simple to use and inexpensive so that the unit may be readily disposable. The invention may be used to locate andor distinguish a substance from other substances, to image a substancefeature and to monitor the movement of an imaged substancefeature. A pressing portion for pressing the recording head in a connector insertion direction of a connecting portion is arranged near a rotational center of the lever member.