Patent ID: 6917502
Filing Date: 2005-07-12
Classification: H02J

Abstract:
1. A power supply circuit for an accessory load of a motor vehicle including a storage battery and an engine driven mechanism coupled to the storage battery for producing supplemental electrical energy during engine operation, the power supply circuit comprising: a switch mechanism having a first state in which the accessory load is connected to the storage battery, and a second state in which the accessory load is disconnected from the storage battery; comparator means for measuring a voltage established by said storage battery and comparing the measured voltage to a reference voltage that is equal to said measured voltage when a terminal voltage of said storage battery equals a switching voltage that is higher than open-circuit voltage of the battery but lower than a minimum voltage produced by the engine driven mechanism during engine operation to determine if the engine driven mechanism is producing supplemental electrical energy; and a timer circuit responsive to the comparison of the measured voltage to the reference voltage for establishing the state of said switch mechanism such that the first state of the switch mechanism is established whenever it is determined that the engine driven mechanism is producing supplemental electrical energy, and the second state of the switch mechanism is established when it is determined that the engine driven mechanism is not producing supplemental electrical energy for at least a predefined time interval.