Abstract: A battery having a rust-preventive structure includes a battery cell, the side-wall and an outer peripheral region of the safety valve end of which are covered with heat-shrink tubing. A sealing plate is attached in a moisture-tight fashion to the heat-shrink tubing on the safety valve end via a pressure separating adhesive layer. Adhesive seals the region between a lead-tab connected to the battery terminal and the sealing plate.

Abstract: To prevent the complete discharge of a battery connected to a load, a battery voltage of the battery is compared with a reference voltage, and a switch is activated to open an electrical connection between the battery and the load when the detected battery voltage falls below the reference voltage. To compensate for dynamic characteristics of the battery and the load, a battery current flowing through the battery is detected and a value of the reference voltage is continuously set according to the detected battery current. Similarly, a battery temperature of the battery also controls the reference voltage. Also, a timer may be provided to cause the switch to open the connection between the battery and the load only when the detected battery voltage remains below the reference voltage for a predetermined period of time.

Abstract: Disclosed is an operating method of a compact phosphoric acid fuel cell system whose operation is started and stopped repeatedly, comprising a lamination of a plurality of cell units each of which has an electrolyte matrix impregnated with a phosphoric acid electrolyte between a positive electrode and a negative electrode, characterized by being operated so that each of the cell units can have a phosphoric acid electrolyte whose density is partially less than 91.6 wt % during the operation.