A mechanical assembly including a pair of members each having a planar surface and a displacing structure can be designed to engage a compressible seal, and thereby reduce or eliminate shear force exerted on the seal, keeping the seal intact during compression. The battery-abnormality detection circuit controls a battery-set circuit separation switch, so as to detect an abnormality in each secondary-battery cell based on a change in the voltage of each cell when parallel-connection separation switches are turned off, and if detecting an abnormal secondary-battery cell, so as to separate the series module including this cell from a battery-set body. A gm-amp charges or discharges a capacity by a current corresponding to the difference between the output voltage from the amplifier circuit and a reference voltage. Moreover, the heat exchanger includes a plurality of outer fins. This issue is addressed by exposing the dielectric to silane coupling agents at various stages of etching and cleaning. In the alternative, a visual indicator can be used, such as a liquid crystal or a light emitting diode display, which informs the user of the shaving changes needed.