Automated battery cell shunt bypass
A battery pack is provided that includes a plurality of battery cells electrically connected in series, the plurality of battery cells including a selected battery cell, and a shorting mechanism operable, upon the occurrence of a selected event, to automatically remove electrically the selected battery cell from the electrically connected battery cells.
1 . A battery pack, comprising:
a plurality of battery cells electrically connected in series, the plurality of battery cells including a selected battery cell; and
a shorting mechanism operable, upon the occurrence of a selected event, to automatically remove electrically the selected battery cell from the electrically connected battery cells.
2 . The battery pack of claim 1 , wherein the selected event is at least one of the following:
(i) an internal resistance of the battery cell in excess of a first selected operating threshold;
(ii) an internal pressure of the battery cell in excess of a second selected operating threshold;
(iii) an internal temperature of the battery cell in excess of a third selected operating threshold;
(iv) a voltage of the battery cell during energy removal in excess of a fourth selected operating threshold; and
(v) a voltage of the battery cell during charging less than a fifth selected operating threshold.
3 . The battery pack of claim 2 , wherein the event is event (i).
4 . The battery pack of claim 2 , wherein the event is event (ii).
5 . The battery pack of claim 2 , wherein the event is event (iii).
6 . The battery pack of claim 2 , wherein the event is event (iv).
7 . The battery pack of claim 2 , wherein the event is event (v).
8 . The battery pack of claim 1 , wherein the shorting mechanism comprises a shorting bar, a sensor that senses the occurrence of the selected event, a controller in communication with the sensor, and a shorting bar deployment member, wherein, when the controller determines from sensor input that the selected event has occurred, the controller causes the shorting bar deployment member to position the shorting bar in contact with positive and negative bus bars of the selected battery cell, thereby shorting out the cell and forming a shunt bypass of the selected battery cell.
9 . The battery pack of claim 4 , wherein the shorting mechanism comprises a piston having a position that changes in response to the internal pressure, a shorting bar, and a shorting bar deployment member, wherein, when the internal pressure rises above the selected operating threshold, the position of the piston causes the shorting bar deployment member to position the shorting bar in contact with positive and negative bus bars of the selected battery cell, thereby shorting out the cell and forming a shunt bypass of the selected battery cell.
10 . The battery pack of claim 5 , wherein the shorting mechanism comprises a thermally expansive material having a length that increases in direct response to the internal temperature, a shorting bar, and a shorting bar deployment member, wherein, when the internal temperature rises above the selected operating threshold, the length of the thermally expansive material causes the shorting bar deployment member to position the shorting bar in contact with positive and negative bus bars of the selected battery cell, thereby shorting out the cell and forming a shunt bypass of the selected battery cell.
11 . In a battery pack comprising a plurality of battery cells electrically connected in series, a method, comprising:
removing electrical energy from and/or inputting electrical energy to the battery pack; and
when a selected battery cell in the battery pack has an operating characteristic beyond a specified operational limit, automatically removing electrically the selected battery cell from the battery pack.
12 . The method of claim 11 , wherein the operating characteristic is at least one of an internal resistance, an internal pressure, an internal temperature, and cell voltage.
13 . The method of claim 12 , wherein the at least one of an internal resistance, an internal pressure, an internal temperature, and a cell voltage is internal resistance.
14 . The method of claim 12 , wherein the at least one of an internal resistance, an internal pressure, an internal temperature, and a cell voltage is internal pressure.
15 . The method of claim 12 , wherein the at least one of an internal resistance, an internal pressure, an internal temperature, and a cell voltage is internal temperature.
16 . The method of claim 12 , wherein the at least one of an internal resistance, an internal pressure, an internal temperature, and a cell voltage is cell voltage.
17 . The method of claim 12 , further comprising:
sensing the at least one of an internal resistance, an internal pressure, an internal temperature, and a cell voltage;
determining that the sensed at least one of an internal resistance, an internal pressure, an internal temperature, and a cell voltage of a selected battery cell is beyond the specified operational limit;
in response to the determining step, repositioning a shorting bar from a first position out of contact with at least one of the positive bus bar and negative bus bar of the selected battery cell to a second position in simultaneous contact with positive and negative bus bars of the selected battery cell, thereby shorting out the cell and forming a shunt bypass of the selected battery cell.
18 . The method of claim 14 , further comprising:
when the internal pressure in a selected battery cell rises above the selected specified operational limit, a piston is moved from a first to a second position, wherein, when the piston is in the first position, a shorting bar is not in contact with at least one of a positive bus bar and negative bus bar of the selected battery cell and wherein, when the piston is in the second position, the shorting bar is in simultaneous contact with positive and negative bus bars of the selected battery cell, thereby shorting out the cell and forming a shunt bypass of the selected battery cell.
19 . The method of claim 15 , further comprising:
when the internal temperature in a selected battery cell rises above the specified operational limit, a length of a thermally expansive material lengths from a first length to a second length, wherein, when the expansive material has the first length, a shorting bar is not in contact with at least one of a positive bus bar and negative bus bar of the selected battery cell and wherein, when the expansive material has the second length, the shorting bar is in simultaneous contact with the positive and negative bus bars of the selected battery cell, thereby shorting out the cell and forming a shunt bypass of the selected battery cell.
20 . A system, comprising:
a plurality of battery cells electrically connected in series, the plurality of battery cells including a selected battery cell;
an electric motor in electrical communication with the battery cells; and
a shunting device operable in a first mode not to shunt a selected battery cell and in a second mode to shunt the selected battery cell, whereby, in the first mode, the selected battery cell provides electrical energy to the electric motor and, in the second mode, the selected battery cell provides no electrical energy to the electric motor.
21 . The system of claim 20 , wherein the shunting device is operable, when the selected battery cell has at least one of an internal resistance, an internal pressure, and an internal temperature in excess of a selected operating threshold, to operate in the second mode.
22 . The system of claim 21 , wherein the at least one of an internal resistance, an internal pressure, and an internal temperature is internal resistance.
23 . The system of claim 21 , wherein the at least one of an internal resistance, an internal pressure, and an internal temperature is internal pressure.
24 . The system of claim 21 , wherein the at least one of an internal resistance, an internal pressure, and an internal temperature is internal temperature.
25 . The system of claim 20 , wherein the shunting mechanism comprises a shorting bar, a sensor that senses the at least one of an internal resistance, an internal pressure, and an internal temperature, a controller in communication with the sensor, and a shorting bar deployment member, wherein, when the controller determines from sensor input that the at least one of an internal resistance, an internal pressure, and an internal temperature is above a selected operating threshold, the controller causes the shorting bar deployment member to position the shorting bar in contact with positive and negative bus bars of the selected battery cell, thereby shorting out the cell and forming a shunt bypass of the selected battery cell.
26 . The system of claim 23 , wherein the shunting mechanism comprises a piston having a position that changes in response to the internal pressure, a shorting bar, and a shorting bar deployment member, wherein, when the internal pressure rises above a selected operating threshold, the position of the piston causes the shorting bar deployment member to position the shorting bar in contact with positive and negative bus bars of the selected battery cell, thereby shorting out the cell and forming a shunt bypass of the selected battery cell.
27 . The system of claim 24 , wherein the shunting mechanism comprises a thermally expansive material having a length that increases in direct response to the internal temperature, a shorting bar, and a shorting bar deployment member, wherein, when the internal temperature rises above a selected operating threshold, the length of the thermally expansive material causes the shorting bar deployment member to position the shorting bar in contact with positive and negative bus bars of the selected battery cell thereby shorting out the cell and forming a shunt bypass of the selected battery cell.