| 摘要 |
<p>The system includes an electronic circuit 68, 70 that minimizes current drain from the vehicle's battery, by controlling the rate at which the siren's back-up battery 72 is charged by the vehicle's battery. The circuit charges the siren's battery 72 at a relatively high rate when the vehicle engine is running or the ignition is on, and at a low charging rate at other times, thereby preserving the vehicle's battery charge particularly if the vehicle is not driven for any extended period. The circuit includes a back-up battery condition detector 74 that issues a warning signal if the voltage of the backup battery 72 is outside a predetermined range. The signal may be given by inhibition of the chip signals normally emitted from siren speaker 64 on arming/disarming the system, or by connecting a chip generator 73 to speaker 64, or by a voice synthesizer 75 or a LED (741, Fig. 2A). The siren sounds in response to a signal from security system 66, and if it is disconnected from system 66 or from the vehicle battery. A timer 76 limits the maximum time for which the siren may sound. <IMAGE></p> |
