Connector with integrated thermal cutoff device for battery packs

Abstract

A temperature-sensitive battery connector is disclosed. The connector can include a connector body and at least one conductor attached to the connector body and configured to conduct a current signal used to measure voltage from a battery pack or battery cell to a battery management system (BMS). The connector can include a thermal switch device attached to the connector body and thermally coupled to a terminal of the battery pack or battery cell. The thermal switch device can be configured to provide an overtemperature signal to the BMS by altering or interrupting current conducted by the at least one conductor when the temperature of the battery pack or battery cell exceeds a threshold temperature.

Description

[Technical Field]

[0001] Incorporation by reference of any priority application All applications for which a foreign or domestic priority claim is identified in the Application Data Sheet filed with this application are hereby incorporated by reference under 37 CFR 1.57.

[0002] The field relates to integrated thermal cut-out devices for sensing the temperature of a cell or battery pack. [Background technology]

[0003] In various types of electrical systems, circuit elements, such as batteries, which may include one or more cells, or other components may experience faults that adversely affect the operation or reliability of the larger electrical system. For example, a battery pack may experience an increase in temperature during operation or charging. If the temperature increase is excessive, the cell or battery pack or the larger electrical system may be damaged by overheating and / or overcurrent faults. Such overheating faults may reduce the functionality, reliability, lifespan, and / or safety of the device. Therefore, there remains a need for devices that protect the larger electrical system when a circuit element (such as a cell or battery) experiences an overheating fault. Summary of the Invention

[0004] In one embodiment, a temperature-sensitive battery connector is disclosed. The temperature-sensitive battery connector can include a connector body and at least one conductor attached to the connector body and configured to carry a signal from a battery pack or battery cell to an electrical device (such as a battery management system (BMS)). The temperature-sensitive battery connector can include a thermal switch device attached to the connector body and thermally coupled to a terminal of the battery pack or battery cell. The thermal switch device can be configured to provide an overtemperature signal to the electrical device by altering the signal carried by the at least one conductor when the temperature of the battery pack or battery cell exceeds a predetermined threshold temperature.

[0005] In another embodiment, an electrical system is disclosed. The electrical system may include a plurality of battery packs and a battery management system (BMS) that manages the plurality of battery packs. Each battery pack of the plurality of battery packs may have at least one battery terminal. The BMS may include a battery management controller and a plurality of status lines. The battery management controller may be configured to monitor the status of the battery packs via the status lines. Each status line of the plurality of status lines may include a connector configured to couple to a battery terminal of a respective one of the battery packs. Each status line of the plurality of status lines may include at least one conductor attached to the connector and coupling the connector to the battery management controller. Each status line of the plurality of status lines may include a thermal switch device attached to the connector. The thermal switch device may be thermally coupled to a battery terminal of a respective one of the battery packs. When a temperature of a respective one of the battery packs exceeds a predetermined threshold temperature, the thermal switch device may change a signal from the battery terminal of the respective one of the battery packs to the battery management controller.

[0006] Specific embodiments of the present invention will now be described with reference to the following drawings, which are provided by way of example and not limitation. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic system diagram of a portion of an electrical system having one or more temperature sensors connected to corresponding battery packs. [Figure 2A] 1 is a perspective image of an electrical system including multiple interconnected battery packs for powering a load. [Figure 2B] 1 is an image showing an enlarged right side perspective view of the battery pack. [Figure 2C] 1 is an image showing an enlarged front perspective view of the battery pack. [Figure 3A] FIG. 1 is a schematic system diagram of a portion of an electrical system, according to one embodiment. [Figure 3B] FIG. 2 is a schematic system diagram of an electrical system according to another embodiment. [Figure 4] FIG. 3B is an enlarged schematic diagram of a portion of the electrical system shown in FIG. 3A. [Figure 5] Figure 5A is a schematic cross-sectional side view of a thermal switching device in normal operation according to various embodiments. Figure 5B is a schematic circuit diagram of the thermal switching device shown in Figure 5A. [Figure 6] Figure 6A is a schematic cross-sectional side view of the thermal switching device of Figure 5A in a fault condition. Figure 6B is a schematic circuit diagram of the thermal switching device shown in Figure 6A. [Figure 7] 1 is a graph illustrating the current and temperature at which an exemplary switch trips from a normal operating condition to a fault condition, in accordance with various embodiments. [Figure 8] 1 is a schematic graph illustrating the relationship between temperature and resistance of an exemplary positive temperature coefficient (PTC) resistor, in accordance with various embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0008] Various embodiments disclosed herein relate to a connector having an integrated thermal switch device, such as a thermal cutoff (TCO), configured to detect an overheat and / or overcurrent condition in a battery pack or battery cell and relay the detection to an electrical device, such as a battery management system (BMS). In various embodiments, a temperature-sensitive battery connector is disclosed. The connector can include a connector body and at least one conductor attached to the connector body and configured to carry a signal that causes the battery management system (BMS) to determine that the temperature of the battery pack or battery cell has exceeded a threshold level. The connector can include a thermal switch device, such as a TCO, attached to the connector body and thermally coupled to a terminal of the battery pack or battery cell. The thermal switch device can be configured to provide an overheat signal to the BMS (or other type of electrical device) when the temperature of the battery pack or battery cell exceeds the threshold temperature by interrupting voltage or current to provide a signal carried by the at least one conductor used to balance one or more cells in a battery (or array of cells). In various embodiments, for example, the signal communicated to the BMS can be generated by a change in resistance, such as a sudden increase in the resistance of a thermal switch device or TCO within the connector body. The BMS can be configured to interpret this signal as an increase in battery pack or battery cell temperature and can send an alarm indicating an overheating condition. In various embodiments, the BMS can shut off one or more (or all) of the cells in response to the alarm. The threshold temperature can be pre-tuned and set for the device by selecting the materials and dimensions of the thermal switch device.

[0009] FIG. 1 is a schematic system diagram of a portion of an electrical system 1 having one or more temperature sensors 21 attached to corresponding battery packs 6. The battery packs 6 can supply power to a load L. Each battery pack 6 can include one or more battery cells 2. An electrical device including a battery management system 25 can connect to the positive terminals 20 of the respective battery packs 6 via corresponding cell balancing lines, which also serve as cell voltage status signal lines in various embodiments disclosed herein (also referred to herein as “status lines 23”). As shown, the positive terminal 20 of a particular battery pack 6 can be connected to the negative terminal 28 of an adjacent battery pack 6. The BMS 25 can receive signals from the battery packs 6 along the status lines 23 that indicate the status of the battery packs 6 (e.g., the voltage status of the battery packs 6). For example, an approximate voltage of the battery pack 6 may be provided to the BMS 25 along status line 23. Additionally, as shown schematically in FIG. 1 , a temperature sensor 21 (e.g., a thermistor) may be physically attached or mounted to the housing structure of the battery pack 6. The temperature sensor 21 may measure the temperature of the battery pack 6 to which it is connected and may transmit the measured temperature (or a characteristic associated with and derivable from the measurement determined by the sensor 21) to the BMS 25 along temperature sensing line 35. Based on the signal transmitted to the BMS 25 along temperature sensing line 35, the BMS 25 may determine whether the battery pack 6 is experiencing an over-temperature and / or over-current condition.

[0010] 1 , the BMS 25 connects to the positive terminal 20 of each battery pack 6 via the status line 23 and monitors the temperature of each battery pack 6 via the temperature sensor 21 and the temperature sensing line 35. The use of multiple thermistors 21 and additional temperature sensing lines 35 can increase the cost and complexity of the electrical system 1. Furthermore, the temperature sensor 21 is typically mounted on the housing of the battery pack 6, which may have poor thermal conductivity, resulting in delays and inaccuracies in measuring the temperature of the cells 2 in the battery pack 6. Therefore, there is a continuing need for improved systems and methods for monitoring the temperature of battery packs.

[0011] FIG. 2A is an image of at least a portion of an electrical system 1 including multiple interconnected battery packs 6 for supplying power to a load L (not shown). FIG. 2B is an image showing an enlarged right side view of the battery pack 6. FIG. 2C is an image showing an enlarged front perspective view of the battery pack 6. Each battery pack 6 can include one or more battery cells 2 (see FIG. 3A), each cell having one or more positive terminals 20 and one or more negative terminals 28 (see FIG. 3A). In the example of FIG. 2A, each battery pack 6 can include multiple cells having three contacts (e.g., positive or negative terminals) to provide electrical communication to the BMS and / or the load L, although any suitable number of contacts or terminals can be provided for each battery pack 6. Additionally, as shown in FIG. 2A, a conductive bus bar 33 can be provided to electrically connect the positive terminal 20 of each battery pack 6 to the negative terminal 28 of an adjacent battery pack 6. An electrical cable 37 can be connected to one of the positive terminals 20 as shown in FIG. 2A. The electrical cable 37 can be configured to apply a high voltage from the series of battery packs 6 to the load L. For example, the electrical cable 37 can supply a voltage of at least 500 V to the load L, at least 700 V to the load L, or at least 1,000 V to the load L.

[0012] The battery cells 2 (see FIG. 3A ) may include any suitable type of battery cells, including, but not limited to, lithium-ion battery cells. It should be understood that each battery pack 6 may include any suitable number of battery cells 2. For example, each battery pack 6 may include at least 100 cells, at least 200 cells, at least 300 cells, at least 400 cells, or at least 500 cells. In one example, each battery pack 6 may include approximately 500 cells arranged in 10 groups of 50 cells arranged in parallel with each other. Furthermore, it should be understood that any suitable number of battery packs 6 may be used in a larger electrical system 1 or system. For example, more than 100 battery packs (e.g., 150 battery packs 6 or 200 battery packs 6) may be used in a system. The electrical system 1 or system may include any suitable type of device for a load L, including, but not limited to, an electric or hybrid vehicle, an electric bicycle, a power tool, or any other suitable battery-powered device.

[0013] The battery pack 6 of FIGS. 2A-2C can include a housing 30 that supports or encloses the battery cells. For example, in various embodiments, the housing 30 is defined by an outer wall and includes one or more The housing 30 may include an internal cavity shaped to receive the battery cell(s) 2. The housing 30 may comprise any suitable type of material, such as a plastic material. In some embodiments, as described above, one or more temperature sensors 21 (e.g., thermocouples, thermistors, or any other suitable type of sensor) may be mechanically and thermally coupled to the housing 30 at a distance from the terminals to avoid short circuits, as shown in FIGS. 1 and 2A. The temperature sensors 21 may monitor the temperature of the housing 30 and may be used to correlate that temperature with the temperature of the battery cell(s) 2 (which may differ from the measured temperature of the housing 30).

[0014] As shown in FIGS. 2A-2C , the positive terminal 20 of each battery pack 6 can be electrically and mechanically connected to a status wire 23 (e.g., a voltage or current detection wire) via a connector 24. The connector 24 can comprise any suitable type of electrical connector, such as a conductive clip, a conductive ring, or a conductive clamp. For example, as shown in FIGS. 2B-2C and 4 , a conductive ring 22 can serve to secure the connector 24 to the positive terminal 20 of the battery pack 6 to mechanically and electrically connect the status wire 23 to the positive terminal 20. Alternatively, in some embodiments, the status wire 23 can be attached to the negative terminal 28.

[0015] The status lines 23 can provide electrical communication between the positive terminal 20 of the battery pack 6 and a battery management system (BMS) not shown in FIGS. 2A-2C (see, e.g., FIGS. 3A-3B). The BMS can receive signals from the battery packs 6 along the status lines 23 that indicate the status of the battery packs 6. For example, the approximate voltage of the battery packs 6 can be provided to the BMS along the status lines 23. Thus, in various embodiments, the BMS can be configured to monitor the status of the battery packs 6. The BMS can also transmit power to the battery packs 6 along the status lines 23 to balance any unbalanced cells 2. In various embodiments, for example, based on the state of charge of each pack 6, the BMS can transfer electrical energy along the status lines 23 to balance the charge of the battery packs 6.

[0016] In the configuration of Figures 2A-2C, the sensor 21 is mounted in a housing 30 that may contain a plastic material and may not be a good thermal conductor by design, and therefore may not provide a direct and accurate measurement of the temperature of the battery cell 2.

[0017] 3A-4, connector 24 may advantageously include a thermally activated switch that can monitor the temperature of battery pack 6 directly at battery pack 6, for example, at positive terminal 20 of battery pack 6 (or at negative terminal 28 of battery pack 6). As described herein, in various embodiments disclosed herein, temperature sensor 21 and associated temperature sensing wires 35 may be omitted, thereby reducing the cost and complexity of device 1.

[0018] Figure 3A is a schematic system diagram of a portion of an electrical system 1, according to one embodiment. Figure 4 is an enlarged schematic diagram of the portion of the electrical system 1 shown in Figure 3A. The depicted portion of the electrical system 1 may provide power to a load L, such as an electric vehicle, an electric bicycle, a power tool, or the like.

[0019] In Figure 3A, an electrical device including a battery management system (BMS) 25 is electrically connected to the positive terminal 20 and the negative terminal 28 of a battery pack 6, which may include one or more cells 2. Although two cells 2 are shown in each battery pack 6 in Figure 3A, any suitable number of cells may be provided per battery pack 6. The BMS 25 may include processing circuitry, which may be connected to one or more battery management controllers 3A shows two complete battery packs 6 and a portion of a third battery pack, but as noted above, the BMS 25 can be electrically connected to any suitable number of battery packs 6. As noted above, the status wire 23 can electrically connect the positive terminal 20 of the battery pack 6 to the BMS 25. Further, the connector 24 can electrically and mechanically connect the status wire 23 to the positive terminal 20 of the battery pack 6. However, as noted above, the status wire 23 can alternatively be connected to the negative terminal 28. Similar to FIG. 2A, the bus bar 33 can electrically connect the positive terminal 20 of each battery pack 6 to the corresponding negative terminal 28 of an adjacent battery pack 6.

[0020] However, unlike the configurations of FIGS. 2A-2C , in the embodiments of FIGS. 3A and 4 , the connector 24 may include an integrated thermal switch device 3 coupled to or formed within a connector body 27 of the connector 24, as shown in FIG. 4 . The connector 24 (e.g., the connector body 27) may include an electrical conductor (e.g., metal) that electrically and mechanically connects to the status wire 23. As shown in FIG. 4 , the thermal switch device 3 and the connector body 27 may be mechanically and thermally connected to the positive terminal 20 of the battery pack 6 through an intervening thermally and electrically conductive ring 22 or by another thermally conductive fastener. For example, the conductive ring 22 may be secured between the connector body 27 and the battery pack 6 with a nut or other fastener. Those skilled in the art will appreciate that additional methods of connecting the connector body 27 and the switch device 3 to the battery pack 6 may also be suitable.

[0021] 3A and 4, the thermal switch device 3 is positioned in physical proximity to the positive terminal 20 of the battery pack 6 and thermally connected to the positive terminal 20 of the battery pack 6 and the cell 2. Indeed, as shown in FIG. 4, the thermal switch device 3 may be in physical contact with the terminal 20 of the battery pack 6 via an intervening thermally conductive ring 22 or other thermally conductive fastening device. In some embodiments, a thermal adhesive may be provided between the thermal switch device 3 and the ring 22 and / or between the ring 22 and the terminal 20. Thus, as shown in FIG. 4, a short thermally conductive path is provided directly between the thermal switch device 3 and the terminal 20 of the battery pack 6. Such a thermally conductive path allows efficient transfer of thermal energy (e.g., heat) from the battery pack 6 (and the cell 2) to the thermal switch device 3.

[0022] The thermal switch device 3 may include a switch 4, such as a thermally actuated switch, configured to transition from a normally closed state to an open state when the temperature of the battery cell 2 exceeds a characteristic temperature threshold. The thermal switch device 3 may function as a thermal fuse and / or a thermal cut-off (TCO) device. The switch 4 may be configured to maintain the normally closed state when the temperature of the battery cell 2 is below the temperature threshold. In the normally closed state, cell balancing may be performed, and one or more status signals from the battery pack 6 may be communicated to and monitored by the BMS 25. Thus, by receiving and processing signals received from the battery pack 6 along the status line 23, the BMS 25 may determine that the battery pack 6 is operating under normal conditions at a temperature below the threshold.

[0023] 3A and 4, the electrical device monitoring the temperature condition of battery pack 6 comprises a BMS, although in other embodiments the electrical device may comprise a motor, a transformer, an electrical component housing, or other suitable electrical device where maintaining the temperature of battery pack 6 or cells below a predetermined threshold temperature is important. In some embodiments, connector 24 may be connected to multiple (e.g., two) electrical or status lines, and tripping of thermal switch device 3 may create an open circuit on the multiple status lines to indicate an overtemperature condition.

[0024] Therefore, during operation, thermal energy from the battery pack 6 can be transferred to the thermal switch device 3 along a short thermal conduction path with little or no heat loss. If the temperature of battery pack 6 (and / or its individual cells 2) is below a threshold temperature, switch 4 may remain closed, and BMS 25 (or other electrical device) may receive a status signal from battery pack 6 and determine that battery pack 6 is operating normally. However, if the temperature of battery pack 6 exceeds a predetermined temperature, switch 4 may transition to an open state, interrupting the signal to BMS 25 along status line 23. BMS 25 may determine that the signal has been interrupted and may indicate to a user that battery pack 6 may be experiencing an overtemperature condition. Furthermore, opening switch 4 may cause the BMS to initiate a process of interrupting the circuit between electrical load L and the portion or all of battery pack 6 that is experiencing the overtemperature condition, thereby advantageously preventing further temperature rise to protect battery pack 6 and the larger electrical system 1.

[0025] For example, in some embodiments, switch 4 can open in response to an increase in temperature, which can send a signal to BMS 25 generated by a change in resistance, e.g., a sudden increase in resistance. In various embodiments, the current along status line 23 can be suddenly decreased. For example, in some embodiments, an analog-to-digital converter (ADC) in BMS 25 can be programmed to calculate a voltage drop based on an increase in resistance, e.g., a PTC resistor or other element of switch 4 whose resistance increases with increasing temperature. BMS 25 can be programmed to interpret the change in current and / or resistance as a voltage drop and, therefore, as a warning or alarm signal indicating that a monitored cell has exceeded a threshold. In response to an overtemperature alarm, BMS 25 can send a command to shut off some or all of cells 2 in battery pack 6.

[0026] In some embodiments, switch 4 can be configured to be non-resettable, such that if switch 4 is flipped or tripped from a normally closed state to an open state, switch 4 remains in the open state. In such a configuration, when switch 4 is opened, it can permanently interrupt the voltage status signals sent to BMS 25, as well as the cell balancing function. Based on this interruption, BMS 25 can determine that battery pack 6 is in an overtemperature fault condition. In some cases, a user may decide to replace a battery pack 6 that has experienced an overtemperature fault condition. In other embodiments, switch 4 can be manually resettable. For example, if switch 4 is flipped or tripped to an open state, BMS 25 can indicate to the user that the signal along status line 23 has been interrupted, which may indicate an overtemperature condition. The user can inspect battery pack 6, and if the temperature has sufficiently decreased or the overtemperature condition has otherwise been addressed, the user can reset switch 4 to the normally closed state, for example, by pressing a button or engaging another interface.

[0027] In still other embodiments, switch 4 may be automatically resettable, as described below in connection with FIGS. 5A-8. In some embodiments, as shown in FIGS. 5A-6B, switch 4 may include a thermal switch element in parallel with a positive temperature coefficient (PTC) resistor, or various combinations of PTC, thermal cutoff (TCO), and / or thermal fuses arranged in parallel or series. In other embodiments, switch 4 may not include a PTC resistor. Switch 4 may have a hysteresis characteristic (see, for example, FIG. 8) that allows switch 4 to transition from a normally closed state to an open state when the temperature exceeds a characteristic threshold and return from the open state to a normally closed state when the temperature falls below a reset threshold. In such a configuration, the signal from battery pack 6 along status line 23 may be intermittently or temporarily interrupted to BMS 25. When the signal is interrupted, BMS 25 can determine that battery pack 6 is in an overtemperature condition and indicate the overtemperature condition to a user. When the temperature drops sufficiently, switch 4 can return to a normally closed state, restoring the voltage signal to BMS 25 and the cell balancing function. Therefore, the BMS 25 determines that the overheating condition has subsided and that the battery pack 6 is operating normally. It is possible.

[0028] Advantageously, the embodiments of FIGS. 3A and 4 can provide a more accurate determination of whether the temperature of the battery pack 6 and its cells 2 is excessive than the temperature sensor 21 shown in FIGS. 1A-2C. For example, in the configurations of FIGS. 1A-2C, the sensor 21 typically detects the temperature of the housing 30 but does not include a direct thermal conduction path to the battery pack 6 and its cells. In contrast, in the embodiments of FIGS. 3A and 4, the thermal switch device 3 is integrated with the connector 24 and is positioned near and in close thermal communication with the terminals 20 of the battery pack 6. Thus, the temperature of the thermal switch device 3 more closely approximates the temperature of the battery pack 6, due at least in part to the thermal proximity between the thermal switch device 3 and the battery pack 6. Furthermore, the thermal switch device 3 can be used to advantageously open (and in some embodiments close) the switch 4 to directly communicate the state of the battery pack 6 to the BMS 25, e.g., whether the battery pack 6 is in a normal operating state or in an over-temperature fault state. For example, as described above, opening the thermal switch device 3 can send a signal to the BMS 25, resulting in a change in resistance (e.g., a sudden increase in resistance), which can serve as an alarm indicating an overtemperature condition. In some embodiments, the use of the switch device 3 integrated with the connector body 27 can eliminate the need for a separate temperature sensor, such as the sensor 21 described in connection with FIGS. 1A-2C, or provide an overtemperature shutdown on the status line 23 independent of such a sensor. Furthermore, as described above, the cable 37 can provide high-voltage power to the load L. The thermal switch device 3 can be configured to withstand high voltages, including voltages of at least 500 V, at least 750 V, or at least 1000 V. For example, the thermal switch device 3 can withstand voltages in the range of 1 V to 2000 V, or 100 V to 1500 V.

[0029] FIG. 3B is a schematic system diagram of an electrical system 1 according to another embodiment. Unless otherwise noted, the components in FIG. 3B may be the same or substantially similar to the like-numbered components in FIGS. 3A and 4 . For example, similar to the embodiments of FIGS. 3A and 4 , a connector 24 may be provided. Similar to FIG. 4 , the connector 4 may include a thermal switch element 3, as described above. Unlike the embodiments of FIGS. 3A and 4 , instead of connecting to a battery pack 6 having multiple cells 2, in the embodiment of FIG. 3B , the connector 24 may be connected to a positive terminal 26 of an individual battery cell 2. A BMS 25 (or other electrical device described above) may be electrically connectable to the positive terminal 26 and the negative terminal 29 of the battery cell 2. As shown in FIG. 4 , a status line 23 may provide electrical communication between the connector 24 and the BMS 25. Similar to the embodiments of FIGS. 3A and 4 , the embodiment of FIG. 3B may similarly monitor the temperature of the battery cell 2. If the temperature of the cell 2 exceeds a predetermined threshold, the switch 4 may open and interrupt the signal to the BMS 25. Additionally, as discussed above, switch 4 can be configured to be non-resettable, manually resettable, or automatically resettable.

[0030] 5A-8 illustrate various embodiments in which the switch device 3 is automatically resettable. However, as noted above, in other embodiments, the switch device 3 may be non-resettable or manually resettable. FIG. 5A is a schematic cross-sectional side view of a thermal switch device 3 in a normal operating state according to various embodiments. FIG. 5B is a schematic circuit diagram of the thermal switch device 3 shown in FIG. 5A. FIG. 6A is a schematic cross-sectional side view of the thermal switch device 3 of FIG. 5A in a fault condition. FIG. 6B is a schematic circuit diagram of the thermal switch device 3 shown in FIG. 6A. The thermal switch device 3 may include a switch 4 connected to a positive temperature coefficient (PTC) resistor 5. For example, in the embodiment of FIGS. 5A-6B, the switch 4 is connected in parallel with the PTC resistor 5, but in other embodiments, the PTC resistor 5 may be connected in other configurations. In still other embodiments, neither the PTC resistor 5 nor the parallel electrical path may be present.

[0031] In the illustrated embodiment, the switch 4 is a thermally actuated mechanical switch, specifically a bimetallic element. As described herein, the PTC resistor 5 can include a resistive element whose resistance increases with increasing temperature. The PTC resistor 5 can be any suitable type of PTC resistor, including a ceramic PTC resistor or a polymer PTC resistor. As shown in FIGS. 5A and 6A , the thermal switch device 3 can include an electromechanical device including a housing 10 to which a first terminal T1 and a second terminal T2 are coupled. The housing 10 can include a first conductive wire 12 electrically connected to the second terminal T2 and the PTC resistor 5 via one or more interconnects 13.

[0032] The switch 4 may include a movable (e.g., pivotable or bendable) conductive arm 8 and a switch element 7. The pivotable arm 8 is electrically connectable to a first terminal T1 and to the switch element 7 via contacts. For example, in a normal state, as shown in FIG. 5A , the pivotable arm 8 may be in electrical contact with a central portion of the switch element 7. For example, in FIG. 5A , the pivotable arm 8 is shown in a normal state, in which a contact 15 on the tip of the pivotable arm 8 is in electrical contact with the first conductive line 12 and the second terminal T2. In FIG. 6A , the pivotable arm 8 is shown in a fault state, in which the pivotable arm 8 is disconnected from the second terminal T2, resulting in an open electrical configuration. In the fault state, the pivotable arm 8 may also be in electrical contact with the switch element 7 at an opposite end of the switch element 7.

[0033] The pivotable arm 8 can transition from a normal state to a fault state by engaging the switch element 7 and the PTC resistor 5. For example, the switch element 7 can include an electromechanical or thermomechanical switch element, specifically a dome-shaped bimetallic element, such as a disk with different metals on different sides that changes shape in response to temperature changes. During normal operation, as shown in FIGS. 5A and 5B , a first current I1 can flow along the pivotable arm 8. Most of the current I2 flows through the second terminal T2, the first conductive wire 12, and the pivotable arm 8 without flowing through the PTC resistor 5. However, a small trickle current I3 (shown by a dashed line) flows from the second terminal T2 and the first conductive wire 12 through the PTC resistor 5 and the switch element 7 to the pivotable arm 8. As described above, during normal operation, the current I2 bypassing the PTC resistor 5 can be much larger than the trickle current I3 through the PTC resistor 5.

[0034] If the temperature and / or current through the thermal switch device 3 exceeds a threshold, the thermal switch device 3 can transition from a normal operating state, as shown in FIGS. 5A-5B, to a fault state, as shown in FIGS. 6A-6B. For example, if the temperature of the switch element 7 exceeds a certain temperature threshold, which can be selected and adjusted in the manufacturing process, such as by material and dimension selection, the switch element 7 can switch from the downwardly curved shape of FIG. 5A to the upwardly curved shape of FIG. 6A. As the current through the PTC resistor 5 increases, the temperature of the PTC resistor 5 and the switch element 7 in contact with the PTC resistor 5 increases, which can also increase the temperature of the switch element 7. The correspondence between resistance and temperature can be nonlinear, as shown in FIG. 8, for example, where a threshold temperature (or temperature range) can result in a significant increase in resistance resulting in a higher temperature increase. When the switch element 7 changes shape to the upwardly curved shape shown in FIG. 6A, the switch element 7 can transition the pivotable arm 8 to an open configuration. Although the switch element 7 is shown as being curved downward in a normal condition and curved upward in a fault condition, it should be understood that in other configurations the thermal switch device may be configured such that the switch element 7 is curved upward during normal operating conditions and curved downward during a fault condition.

[0035] During a fault configuration, as the temperature of the PTC resistor 5 increases, the resistance increases accordingly, reducing the current flowing through the thermal switch device 3. As will be explained in more detail below with respect to FIG. Trickle current I3 can supply a small amount of current from the battery pack or cell to enable essential device function because the heat generated by PTC resistor 5 maintains a high temperature after an initial fault condition to prevent switch 4 from chattering, i.e., repeatedly switching between fault and normal operating modes. Thus, in some embodiments, PTC resistor 5 can be used when chattering is an issue for the switch device. In other embodiments, when chattering is not an issue, the PTC resistor may be omitted; for example, the bimetal disk design can be adjusted to eliminate the need for a PTC resistor. Those skilled in the art will understand that trickle current I3 through PTC resistor 5 can have different magnitudes under normal and fault conditions, and that the magnitude of I3 can change during the occurrence of a fault condition.

[0036] FIG. 7 is a graph illustrating the current and temperature at which an exemplary switch 4 trips from a normal operating state to a fault state, according to various embodiments. Specifically, FIG. 7 is a plot of current versus temperature for a dome-shaped bimetal switch used in the Komatsulite™ KCA series Type A breaker, commercially available from Bourns, Inc. of Riverside, California. Specifically, FIG. 7 plots current versus temperature for four different versions of the Type A breaker from the previous series. In FIG. 7, the lines represent the temperature and current combinations at which a particular breaker trips to a fault state. Thus, the area below each line indicates a normal state, and the area on and above the line indicates a fault state. As shown in FIG. 7, switch 4 can trip from a normal operating state to a fault state at relatively high temperatures (even at low currents) and / or relatively high currents (even at low temperatures). For example, switch 4 can trip from a normal operating state to a fault state when it reaches a preset threshold temperature in the range of 65°C to 85°C, or more specifically, in the range of 70°C to 80°C, depending on the design.

[0037] The use of a PTC resistor 5 can provide various advantages in some embodiments. As described herein, by maintaining a high temperature after an initial fault condition, the PTC resistor 5 can allow the switch 4 and thermal switch device 3 to operate stably, so that the thermal switch device 3 does not rapidly chatter between normal and fault states. Instead, due to hysteretic behavior, in some circumstances, the temperature of the switch device 3 must be allowed to drop significantly before resetting the thermal switch device 3 from a fault state to a normal operating state.

[0038] 8 is a schematic graph illustrating the relationship between temperature and resistance of an exemplary PTC resistor, according to various embodiments. For example, as shown in FIG. 8, at a predetermined fault temperature T f At temperatures below this, the resistance R of the PTC resistor 5 PTC can be relatively low (however, the resistance R S (It may be higher than the predetermined fault temperature T f When the temperature reaches PTC 5A-6B, the temperature of the PTC resistor 5 can be increased significantly. In the thermal switch device 3 of FIGS. 5A-6B, the increase in temperature of the PTC resistor 5 can further increase the temperature of the switch element 7 in contact with the PTC resistor 5. In this way, the increase in temperature of the PTC resistor 5 can accelerate or assist in changing the shape of the switch element 7 and tripping into the fault state shown in FIGS. 6A-6B, thereby achieving the fast response time of the thermomechanical switch.

[0039] Advantageously, the hysteresis shown in Figure 8 can prevent the thermal switch device 3 from operating in chattering mode. In chattering mode, without the hysteresis shown in Figure 8, as the temperature decreases (even slightly), the temperature of the bimetallic switch element 7 decreases and prematurely returns to normal operating conditions. If the operating current increases, the temperature of the switch element 7 will rise above the fault temperature T fThe voltage may rise above this level and the breaker may switch from normal operation to a fault state and back again. This is undesirable and can lead to instability in the larger electrical system or device 1.

[0040] 5A-6B can advantageously maintain stable operating and fault conditions using a PTC resistor 5 connected (e.g., in parallel) with the switch 4. The thermal switch device 3 of FIGS. 5A-6B can advantageously be resettable in some configurations so that the breaker 3 can return to a normal operating state once the fault condition has subsided (e.g., due to a sufficient drop in current and / or temperature). Furthermore, as described herein, the thermal switch device 3 can stably transition to a fault state and back to a normal operating state without chattering.

[0041] In other embodiments, as described above, the thermal switch device 3 may be manually resettable, or may not be resettable at all. In such embodiments, for example, there may be no PTC resistor in the thermal switch device 3 and no electrical path in parallel with the switch 4. In such a configuration, if the switch 4 trips in a fault condition, the switch 4 may remain in a permanently open configuration to prevent current from flowing to or from the BMS. In some embodiments, the thermal switch device 3 may include a button or other manual user interface that allows a user to manually reset the thermal switch device 3 to its normal operating configuration. Additionally, other configurations of the thermal switch device 3 may be appropriate.

[0042] While the present invention has been disclosed in connection with specific embodiments and examples, it will be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses of the invention, as well as obvious modifications and equivalents thereof. Moreover, while several variations of the invention have been shown and described in detail, other modifications within the scope of the invention will be readily apparent to those skilled in the art based on this disclosure. Various combinations or subcombinations of specific features and aspects of the embodiments may be made and still fall within the scope of the invention. It is understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another to form varying aspects of the disclosed invention. Accordingly, the scope of the invention disclosed herein should not be limited by the specific disclosed embodiments described above, but should be determined solely by a proper reading of the following claims.

Claims

1. a connector body that is mechanically connected to the terminal of the battery cell; at least one conductor attached to the connector body and configured to conduct signals from the battery pack or battery cell to an electrical device; a thermal switch device mounted on the connector body and thermally coupled to a terminal of a battery pack or battery cell, the thermal switch device being in physical contact with the terminal of the battery pack or battery cell via a thermally conductive fastening device, whereby the thermal switch device is configured to monitor temperature directly at the terminal of the battery pack or battery cell, and to provide an over-temperature signal to the electrical device by altering the signal carried by the at least one conductor when the temperature of the battery pack or battery cell exceeds a predetermined threshold temperature; A temperature sensitive battery connector comprising:

2. 10. The temperature sensitive battery connector of claim 1, wherein the electrical device comprises a battery management system (BMS).

3. 2. The temperature sensitive battery connector of claim 1, wherein the signal conveyed by the at least one conductor to the electrical device comprises a voltage status signal when the temperature of the battery pack or battery cell is below the predetermined threshold temperature.

4. 2. The temperature sensitive battery connector of claim 1, wherein said modified signal is a change in current through said at least one conductor.

5. 5. The temperature sensitive battery connector of claim 4, wherein the thermal switch device is configured to provide the over-temperature signal to the electrical device by varying the current through the at least one conductor.

6. 2. The temperature sensitive battery connector of claim 1, wherein the modified signal is produced by a change in resistance of at least one component of the thermal switch device.

7. 2. The temperature sensitive battery connector of claim 1, wherein the thermal switch device is configured to provide a normal temperature signal to the device when the temperature of the battery pack is below a threshold temperature by conducting the signal from the at least one conductor to the device.

8. 2. The temperature sensitive battery connector of claim 1, wherein the thermal switch device is a thermal fuse or thermal cut-off (TCO) device.

9. 10. The temperature sensitive battery connector of claim 1, wherein said thermal switch device is non-resettable.

10. 10. The temperature sensitive battery connector of claim 1, wherein said thermal switch device is manually resettable.

11. 11. The temperature sensitive battery connector of claim 10, further comprising a user interface that, when engaged by a user, manually resets the thermal switch device.

12. 10. The temperature sensitive battery connector of claim 1, wherein said thermal switch device is automatically resettable.

13. 13. The temperature sensitive battery connector of claim 12, wherein the thermal switch device comprises a thermally actuated switch element and a positive temperature coefficient (PTC) resistor in parallel with the thermally actuated switch element, and the modified signal indicates a change in resistance of the PTC in parallel with the thermally actuated switch element.

14. 14. The temperature sensitive battery connector of claim 13, wherein the thermally actuated switch element comprises a bimetallic dome switch element.

15. A temperature-sensitive battery connector as described in claim 1, wherein the thermally conductive fastening device is a conductive ring for mechanically and thermally connecting the connector body to the terminal of the battery pack or battery cell.

16. A plurality of battery packs; a battery management system (BMS) that manages the plurality of battery packs, each battery pack of the plurality of battery packs having at least one battery terminal, A battery management controller; a plurality of status lines, wherein the battery management controller is configured to monitor a status of the battery pack via the status lines, and each status line of the plurality of status lines: a connector configured to couple to a respective one of the battery terminals of the battery pack; at least one conductor attached to the connector and coupling the connector to the battery management controller; a thermal switch device attached to the connector, the thermal switch device thermally coupled to the battery terminal of the respective one of the battery packs and in physical contact with the battery terminal of the respective one of the battery packs via a thermally conductive fastener, thereby monitoring a temperature directly at the battery terminal of the respective one of the battery packs, and when the temperature of the respective one of the battery packs exceeds a predetermined threshold temperature, the thermal switch device changes a signal from the battery terminal of the respective one of the battery packs to the battery management controller.

17. 17. The electrical system of claim 16, wherein the battery management controller is configured to detect that at least one of the battery packs is at a temperature above the predetermined threshold temperature based on detecting an open circuit condition on at least one of the status lines. Hmm.

18. 17. The electrical system of claim 16, wherein the thermal switch device for each status line is integral with the connector for the respective status line.

19. The electrical system of claim 16 , wherein the thermal switching device is a thermal fuse or thermal cut-off (TCO) device.

20. 17. The electrical system of claim 16, wherein the thermal switch device is non-resettable.

21. 17. The electrical system of claim 16, wherein the thermal switch device is manually resettable.

22. 22. The electrical system of claim 21, further comprising a user interface that, when engaged by a user, manually resets the thermal switch device.

23. 17. The electrical system of claim 16, wherein the thermal switch device is automatically resettable.

24. 24. The electrical system of claim 23, wherein the thermal switching device comprises a thermally activated switching element and a positive temperature coefficient (PTC) resistor in parallel with the thermally activated switching element.

25. 25. The electrical system of claim 24, wherein the thermally actuated switch element comprises a bimetallic dome switch element.

26. The electrical system described in claim 16, wherein the thermally conductive fastening device is a conductive ring for mechanically and thermally connecting the connector to the terminal of the battery pack or battery cell.

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