Abstract: A transmitter (100) incorporates an energy storage device (112) to improve operation at low temperature ranges by preventing a battery voltage from dropping below a nominal value of a PLL (104). A processor (106) in the transmitter (100) checks a voltage across the battery (102) during a previous transmission and monitors the temperature from a temperature sensor (110). If the battery voltage and/or the temperature fall below a selected threshold, the energy storage device (112) stores energy that is released when the PLL (104) transmits a signal. By supplementing the energy from the battery (102) with energy from the energy storage device (112), the transmitter (100) keeps the battery voltage from dropping below the nominal value.

Abstract: This invention includes a circuit for displaying charge status to a user. The circuit includes circuitry for comparing a supply or reference voltage to a cell voltage, circuitry for sensing charging current and circuitry for displaying at least one of three charging states to a user. The circuit compares the supply or reference voltage to the cell voltage while sensing current. If the difference between the supply or reference voltage is great, and current is small, the circuit indicates a trickle charging mode. If the charging current is large, the circuit indicates rapid charge. If the difference between the supply or reference voltage is small, and the current is small, the circuit indicates a top off mode. The circuit preferably includes a plurality of comparators for both sensing and comparing the voltages and currents. A pair of light emitting diodes preferably indicates the state of charge to the user.

Abstract: A backup electrical power unit for an alarm panel. The unit comprises a solar panel array which produces an array output DC voltage and a charging current for a battery through a first circuit at a first voltage level of the battery output voltage. This circuit disconnects the array output from the battery terminal output at a second battery voltage level. The charging current resumes when the battery output voltage is at or below the first voltage level. The backup unit also includes a second circuit interposed electrically, serially with the first circuit to disconnect the array output from the battery terminal output below a disconnect, voltage level. A circuit is provided for connecting the battery to the alarm panel when the primary power to the alarm panel is interrupted. Status indicators are provided.

Abstract: A transmitter (100) incorporates an energy storage device (112) to improve operation at low temperature ranges by preventing a battery voltage from dropping below a nominal value of a PLL (104). A processor (106) in the transmitter (100) checks a voltage across the battery (102) during a previous transmission and monitors the temperature from a temperature sensor (110). If the battery voltage and/or the temperature fall below a selected threshold, the energy storage device (112) stores energy that is released when the PLL (104) transmits a signal. By supplementing the energy from the battery (102) with energy from the energy storage device (112), the transmitter (100) keeps the battery voltage from dropping below the nominal value.

Abstract: A battery capacity detection device and the method for the same are disclosed. The charge time for the capacitor in an RC circuit and a lookup table are employed to determine the charge capacity of the battery. The disclosed device uses a microprocessor with a programmable pin to form a discharge loop that controls the RC circuit. Therefore, the microprocessor can measure the current charge capacity of the battery after each time the capacitor discharges by measuring the time needed for the capacitor to get fully charged.