Abstract: A battery circuit, including a secondary battery, a storage capacitor, two switches and two voltage monitor circuits, detects a remaining capacity of the secondary battery and sends out data indicative of the remaining capacity to outside of the battery circuit. A first switch connects a secondary battery to a storage capacitor. A second switch connects the other end of the first switch to the storage capacitor and a load. A storage capacitor voltage monitor circuit measures voltage of the storage capacitor. The first switch is then turned ON and a current from the battery is transferred to the storage capacitor. At this time, the second switch is OFF. Then, the first switch is then turned OFF, and voltage of the storage capacitor indicative of the voltage of the secondary battery is measured. Then, the second switch turns ON and the current flows from the storage capacitor to the external load.

Abstract: Current flows from the secondary battery via the current mirror circuit to the regenerative capacitor. The current mirror circuit multiplies by a numerical constant the current flowing from the secondary battery and supplies the amplified current through the regenerative capacitor. When a voltage value of the regenerative capacitor reaches a predetermined maximum value, the current flows from the regenerative capacitor to the external load. The current flow from the regenerative capacitor continues until the voltage decreases to a predetermined minimum value. Immediately before the voltage of the regenerative capacitor reaches the predetermined minimum value, a terminal voltage of the secondary battery in an open state is measured. This structure enables a charging-and-discharging microcurrent from the secondary battery to be easily monitored, while simultaneously detecting a remaining capacity of the secondary battery.

Abstract: A lithium battery made with a bipolar polyimide membrane with metal layers on each side, including one embodiment where the polyimide has a gold layer on each side. Different formulations for the positive electrode active material are used. The positive electrode active materials are essentially three substances: first, a lithium compound selected from the group consisting of LiCoO2, LiNiO2, and LiMn2O4; second, a powder selected from the group consisting of AB (acetylene black powder) and graphite; and third, PVDF (polyvinyldifluoride). The negative electrode active material consists essentially of two substances: the first is graphite powder; the second is PVDF (polyvinyldifluoride). The positive electrode metals include gold and aluminum. The negative electrode materials include gold, copper, nickel, titanium and iron. A separator layer of polyethylene is used so the battery layers can be wound. Because of the strength of the polyimide, the battery can be tightly wound.

Abstract: The difficulties encountered with attaching tabs to very thin metal layer, e. g., a layer of gold from 0.3 .mu.m to 50 .mu.m thick are severe. Typically, in the uses envisioned for the thin metal layer, which is for a compact battery, a plastic sheet such as polyimide underlies the thin metal layer. Polyimide has a relatively low melting point. The thin polyimide substrate melts when resistance welding is used. Ultrasonic welding doesn't work because the sound wave energy is absorbed by the polyimide. This invention solves the attachment problem by using wire bonding to the thin metal sheet and to its tab. The tab attachment for a thin metal layer comprises a thin metal layer, a metal tab, and a wire and the wire is bonded to the thin metal layer and the wire is bonded to the metal tab. The thin metal layer may be gold; the thickness of the gold is between 0.3 .mu.m and 50.0 .mu.m.