Abstract: A passive battery discharge apparatus located within a cap. The cap extends over battery contacts to be discharged. The discharge apparatus includes a conductive material with specified volumetric resistivity properties that is formed into a pad. The cap is positioned over the contacts so that the pad touches and spans between the contacts to be discharged. A spring insures good contact between the pad and the battery contacts. A metal heat sink provides added thermal control. The discharge apparatus provides an economical solution to safely transport batteries that are beyond their useful service life by avoiding circuit components in favor of conductive elastomers or conductive foams.

Abstract: A safety circuit for lithium-ion and lithium polymer cells which provides for greater accuracy in control of the limiting voltages and currents during discharging and recharging and which includes recognition circuitry to determine presence of a particular battery type. MOSFETS, normally used to provide charge limiting voltages, in recharging cells or batteries but which are relatively imprecise, are removed from the circuit to the extent that they are not used in the measurement of current for control purposes. The function of current limit determinations is instead provided by highly accurate resistive elements.

Abstract: A battery safety device and circuit which prevents detrimental effect from the three most common battery faults generally encountered, excessive heat generation, voltage reversal and short circuit problems. The device includes fast acting circuits which latch the battery in the off state until reset by removal of the load, thereby preventing continued cycling of the battery between on and off states. The safety device includes a gating transistor such as a MOSFET (metal-oxide semiconductor field-effect transistor) switch, a latching timer (RC circuit) and a latching circuit having a transistor which turns on when a charge is 0.5 volts or greater. The safety device further comprises one or more sensor switches triggered by predetermined thermal, pressure, etc., conditions, with the switches being outside the circuit (and not affected by circuit conditions) and adapted to provide a latching voltage to the gating transistor under a detected untoward condition.