Batteries for use in implantable medical devices
First Claim
1. A system for over-charge protection of a multi-cell battery pack when one of the cells has been disconnected, the system comprising:
- a circuit comprising N cells, each cell having a maximum voltage V, wherein each cell comprises;
a fuel gauge configured to monitor a value of a parameter of the cell;
a first transistor controlled by the fuel gauge, the first transistor configured to close when the value meets a threshold, thereby disconnecting the cell from the circuit; and
a unit configured to sense a voltage across the cell and to cause a second transistor to close to bypass the cell when the voltage is greater than a threshold and to open when the voltage is smaller than the threshold, thereby preventing the multi-cell battery pack from charging past the voltage of V(N−
1).
1 Assignment
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Accused Products
Abstract
Multi-cell battery packs can be made safer with certain features that mitigate the consequences of cell failure. Parameters of a cell are monitored to determine when the cell should be disconnected from the pack in case of a fault. The battery is reconfigured to continue operating in a safer mode. An over-charging prevention system reduces the maximum voltage that remaining battery pack can be charged to, so that the cells do not overcharge. Additional circuitry allows the disconnected cell to be periodically reconnected to the battery pack to determine if its conditions have sufficiently improved. The cells also include components for self-powering these cell functions while it is disconnected from the rest of the circuit.
84 Citations
36 Claims
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1. A system for over-charge protection of a multi-cell battery pack when one of the cells has been disconnected, the system comprising:
a circuit comprising N cells, each cell having a maximum voltage V, wherein each cell comprises; a fuel gauge configured to monitor a value of a parameter of the cell; a first transistor controlled by the fuel gauge, the first transistor configured to close when the value meets a threshold, thereby disconnecting the cell from the circuit; and a unit configured to sense a voltage across the cell and to cause a second transistor to close to bypass the cell when the voltage is greater than a threshold and to open when the voltage is smaller than the threshold, thereby preventing the multi-cell battery pack from charging past the voltage of V(N−
1).- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for automatically bypassing a battery cell that has been disconnected in a multi-cell battery pack and recovering when the battery cell is reconnected, the system comprising:
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an oscillator circuit comprising a capacitor configured to store power; a transistor electrically connected to the oscillator circuit, the transistor configured to assume;
(i) an open position to direct current through a battery cell that has been disconnected from a circuit comprising a plurality of battery cells; and
(ii) a closed position to bypass the battery cell;wherein the oscillator circuit is configured to periodically open the transistor to cause a determination to be made as to whether the battery cell has been reconnected to the circuit. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method for mitigating a battery condition in a multi-cell battery pack, the method comprising:
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providing a multi-cell battery pack comprising a first cell, a second cell, and a third cell operating at a desired voltage; monitoring a value of a parameter for each of the first, second, and third cells; comparing the three values; determining that the value corresponding to the first cell differs from the other two values beyond a predetermined threshold; and disconnecting the first cell from battery pack. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification