System for automatically charging the battery of a remote transmitter for use in a vehicle security system

• Main Authors: Nantz, John S, Ghabra, Riad, Tang, Qingfeng, King, Ronald O, Campbell, Douglas C
• Format: Patent
• Language: English
• Published: 02.04.2002

The present invention relates to systems for automatically charging the battery of a remote transmitter which is used in a vehicle security system. A system for automatically charging a battery of a remote keyless entry transmitter includes a voltage monitoring circuit having a first microprocessor which monitors battery voltage and which causes the transmitter to send an RF signal to a receiver in the form of a base station on a motor vehicle. The signal causes a charging circuit of the base station to activate an inductive field to cause the battery to be fully charged. In one embodiment, the first microprocessor also causes the transmitter to send a second signal to the base station to shut down the charging field when the battery voltage reaches a predetermined upper limit. In another embodiment, a second microprocessor of the base station tracks the charging time and shuts down the charging field when the charging time reaches a predetermined amount. Alternatively, charging can be done by direct contact or other means. In this way, the system not only allows for extended battery life by limiting the number of charge cycles on the battery but also allows for optimum discharge of the battery before a charging cycle begins.