Patent ID: 7573239
Filing Date: 2009-08-11
Classification: H02J

Abstract:
1. An alarm system comprising a rechargeable battery power supply, a primary electrical power supply and alarm system control circuitry, wherein the rechargeable power supply includes a charge path and a discharge path and further comprises: at least two (2) battery receptacles for holding and maintaining at least two (2) batteries in a parallel electrical configuration, wherein each receptacle includes a first battery contact terminal, a second battery contact terminal, and a battery holder for physically holding and electrically connecting each battery at the battery's cathode electrode and anode electrode, and wherein every first battery contact terminal is connected to the power supply discharge path; at least two (2) diodes, where each diode is electrically connected between the second battery contact terminal of a respective battery receptacle and the power supply charge path; at least two (2) resistors, where each resistor is connected at a first end to the power supply discharge path, and at a second end to a respective second battery terminal and a respective diode cathode; a missing battery detect circuit including an input port electrically connected to each second battery contact terminal, respective diode cathode and respective resistor second end; and at least two (2) switches, where each switch is connected across each respective diode, wherein a closed switch contact state electrically removes the respective diode from the respective receptacle charge path, and an open switch state electrically includes the respective diode in the respective receptacle charge path, and wherein the missing battery detect circuit detects whether the respective battery is present in its respective battery receptacle without interrupting power supply discharge operation.