Method and apparatus for monitoring the self discharge of a secondary battery upon completion of a charge cycle
First Claim
1. A battery charger for charging a secondary battery connected thereto, comprising:
- a charger controller having a high side sense input terminal connected to a high side of said battery, a low side sense input terminal connected to a low side of said battery, and a switch control output terminal; and
a first switch connected to said low side of said battery and a ground node, said first switch controlled by said switch control output terminal of said charger controller;
wherein after fully charging said battery, said charger controller monitors a terminal voltage of said battery by creating a high impedance node at said low side of said battery, regulating a battery high side voltage to a predetermined value lower than a maximum allowable terminal voltage for said battery, and measuring a battery low side voltage.
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Accused Products
Abstract
A battery charger monitors the terminal voltage of a secondary battery connected thereto with no appreciable depletion of the battery energy. Upon the completion of the charge cycle, the battery charger monitors the terminal voltage of the battery by first creating a high impedance node at the battery low side, and then regulating the battery high side voltage to a value below the maximum allowable terminal voltage for the battery. The battery low side voltage will decreases in response to a value below ground. The charger monitors the terminal voltage across the battery by measuring the battery low side voltage When the battery charger detects that the battery has discharged to a predetermined capacity level, the charger initiates a charge maintenance mode. The battery charger either refreshes the battery or maintains the battery at the predetermined capacity level.
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Citations
23 Claims
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1. A battery charger for charging a secondary battery connected thereto, comprising:
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a charger controller having a high side sense input terminal connected to a high side of said battery, a low side sense input terminal connected to a low side of said battery, and a switch control output terminal; and a first switch connected to said low side of said battery and a ground node, said first switch controlled by said switch control output terminal of said charger controller; wherein after fully charging said battery, said charger controller monitors a terminal voltage of said battery by creating a high impedance node at said low side of said battery, regulating a battery high side voltage to a predetermined value lower than a maximum allowable terminal voltage for said battery, and measuring a battery low side voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for monitoring a terminal voltage of a secondary battery upon completion of a charge cycle, said battery having a battery low side and a battery high side, said method comprises the steps of:
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creating a high impedance node at said battery low side; regulating a high side voltage at said battery high side to a predetermined value less than a maximum allowable terminal voltage of said battery, said step of regulating said high side voltage causing a low side voltage at said battery low side to decrease to a value less than ground; and measuring said low side voltage relative to a reference voltage value; wherein said low side voltage increases towards said reference voltage value as said battery discharges through self-discharge. - View Dependent Claims (16, 17, 18)
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19. A method for monitoring a terminal voltage of a secondary battery upon completion of a charge cycle, said battery having a battery low side and a battery high side, said method comprises the steps of:
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providing a battery charger controller having a high side terminal and a low side terminal; providing a first switch connected between said low side terminal and a ground node, said first switch controlled by said battery charger controller; connecting said battery high side to said high side terminal and said battery low side to said low side terminal of said charger controller; applying a predefined voltage to said first switch to open said first switch; creating a high impedance node at said low side terminal of said charger controller; regulating a high side voltage at said battery high side to a predetermined value less than a maximum allowable terminal voltage of said battery, said step of regulating said high side voltage causing a low side voltage at said battery low side to decrease to a value less than ground; and measuring said low side voltage relative to a reference voltage; wherein said low side voltage increases towards said reference voltage as said battery discharges through self-discharge. - View Dependent Claims (20, 21, 22, 23)
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Specification