Modular Battery System and Components
A battery cell connector for a battery module includes a pair of cantilevered arms and base portions that are linked at the base portion by a bridge. An interconnect board for connecting a plurality of battery cells includes a circuit board and a plurality of battery cell connectors. A battery block system includes a battery block that has a tray and a plurality of battery cells, and an interconnect board in mating relationships with the tray. A battery system includes first and second bus bars, a first and second pluralities of battery cells, and an interconnect board having a plurality of battery cell connectors linking the first and second plurality of battery cells.
This application is a continuation of U.S. application Ser. No. 14/095,149, filed Dec. 3, 2013, which claims the benefit of U.S. Provisional Application No. 61/889,436, filed on Oct. 10, 2013. The entire teachings of the above applications are incorporated herein by reference.
BACKGROUND OF THE INVENTIONMany devices, including computers and electric vehicles, are powered by secondary (rechargeable) batteries, such as lithium-ion, nickel cadmium, nickel-metal hydride and lead acid batteries. Many of these devices consume enough electricity to require that conventional secondary batteries be connected collectively in modular form, such as in battery modules of six, eight, or up to several dozen batteries per module. Devices may operate at voltages requiring series connections of cells to achieve this voltage. Parallel connections of cells increase the total energy capacity available. However, secondary batteries, such as the lithium-ion secondary batteries, typically can vary from cell-to-cell and, therefore, must be monitored (for safety, life, discharge and charge limits) during charging and discharging. When necessary, they must be charged separately or selectively discharged in order to balance the cells in each battery module and maximize the collective efficiency and utilization of the individual cells.
Further, some cells have shorter cycle lives than others within a single battery module, and it can be difficult to selectively access and replace individual modules, thereby deleteriously affecting the performance of the battery system and the device as a whole. This, in addition to an inability of many battery systems to identify individual cells failing within a module, often requires that the module be replaced, thereby adding to the expense of maintenance associated with the battery system, and reducing the efficiency and utility of the device relying upon the battery system.
Therefore, a need exists for a modular battery system that overcomes or minimizes the above-referenced problems.
SUMMARY OF THE INVENTIONThe invention generally is directed to a battery cell connector, an interconnect board for connecting a plurality of battery cells, a battery block system, and a battery system.
In one embodiment, the invention is a battery cell connector that includes a pair of cantilevered arms in spaced relation to each other. Each arm has a base portion and a cantilevered portion. Each base portion defines an edge portion, wherein each cantilevered portion extends from its base portion, and the cantilevered portions are splayed away from each other with distance from their respective base portions. A bridge links the arms at the base of the arm, and supports the arms in spaced relation to each other at the edge portion of each base portion. The base portions of the bridge together define a U-shape in a plane that is transverse to a major longitudinal axis of the at least one arm.
In another embodiment, the invention is an interconnect board for connecting a plurality of battery cells. The interconnect board includes a circuit board including at least one electrically-conductive channel and a plurality of battery cell connectors at the circuit board. At least a portion of the battery cell connectors are in electrical communication with each other through the electrically-conductive channel. Each battery cell connector includes a pair of terminals on opposite sides of the circuit board that are in electrical communication with each other. At least a portion of the battery cell connectors each include a pair of cantilevered arms in spaced relation to each other. Each arm has a base portion and a cantilevered portion. Each base portion defines an edge portion and each cantilevered portion extends from its base portion. The cantilevered portions splay away from each other with distance from their respective base portions. A bridge links the arms at the base of the arm, and supports the arms in spaced relation to each other at the edge portions of each base portion. The base portions of the bridge together define a U-shape in a plane that is transverse to a major longitudinal axis of at least one arm.
In still another embodiment, the invention is a battery block system that includes a battery block and an interconnect board. The battery block includes a tray and a plurality of battery cells. The plurality of battery cells are assembled within the tray, wherein first terminals of the plurality of the battery cells are aligned in a first plane at a first end of the battery block and second terminals of each of the plurality of battery cells are aligned in the second plane at a second end of the battery block. The interconnect board is in mating relationship with the tray. The interconnect board includes a plurality of battery cell connectors, wherein each battery cell connector includes a pair of terminals on opposite sides of the interconnect board that are in electrical communication with each other.
In yet another embodiment, the invention is directed to a battery system that includes a first bus bar, a plurality of battery cells connected in parallel to the first bus bar at respective first terminals, a second bus bar, a second plurality of battery cells connected in parallel to the second bus bar and an interconnect board. The second plurality of battery cells is connected in parallel to the second bus bar at respective first terminals, each of the battery cells of the first plurality of cells being connected in series to a battery cell of the second plurality of battery cells, thereby enabling electrical current flow between the first and second bus bars via plural series connections between the first and second pluralities of battery cells. The interconnect board has a plurality of battery cell connectors that provide electrical communication between at least one pair of battery cells of the first and second pluralities of a battery cells, and further includes an electrically-conductive channel connecting the plurality of battery cell connectors.
In still another embodiment, the invention is a battery block system that includes a battery block and two connector bus bars. The battery block includes a tray and a plurality of battery cells. The plurality of battery cells are assembled within the tray, wherein first terminals of the plurality of the battery cells are aligned in a first plane at a first end of the battery block and second terminals of each of the plurality of battery cells are aligned in the second plane at a second end of the battery block. A connector bus bar is in mating relationship with the tray on each end of the block. The connector bus bar includes a plurality of battery cell connectors, each of which connects a battery cell to the connector bus bar.
The invention provides many advantages. For example, the battery cell connector of the invention can be conveniently attached to a circuit board without requiring assembly of the connector during attachment to the circuit board. In addition, the cantilevered arms of the battery cell connector can provide electrical contact between the battery cells without requiring a permanent or semi-permanent mechanical connection, such as solder, weldment, bonding, or permanent mechanical fastening, thereby enabling the battery cells be easily assembled and separated. Further, the battery cell connectors of the invention are easily fabricated from a single, continuous piece of metal, thereby eliminating the electrical resistance inherent in the interfaces between conductors. This also improves the reliability of the connection.
The interconnect board of the invention includes a circuit board of at least one electrically-conductive channel that enables features including cell balancing and monitoring of battery cells connected to the circuit board. The monitoring of battery cells can include, for example, the state of charge and temperature of the individual battery cells. Individual monitoring of cells in a plurality of battery cells, such as the plurality of cells of a battery module, enables identification of individual cells that require replacement while the battery module is in operation, and without requiring removal of the entire battery module and individual testing of battery cells of the module.
The battery block system of the invention includes a battery block that includes a tray and a plurality of battery cells, and an interconnect board in mating relationship with the tray. The tray, with the batteries, are easily separated from the interconnect board as a unit, and easily substituted or reassembled to form a new battery block system, as necessary. In addition, the battery system of the invention, like the battery block system of the invention, can be easily assembled and disassembled, and can be stacked to form a battery system that employs several stacked trays of battery cells, all connected through interconnect boards between each tray, thereby enabling the formation of a battery system with any number of trays of battery cells, and which can be disassembled, as necessary, to remove and replace individual trays of battery cells or, even, individual cells within battery trays, said individual cells having been monitored through the interconnect board of the battery system. Other advantages of Applicants' invention will be made apparent with description of the various exemplary embodiments set forth below.
The disclosed busbar and interconnect design for large format batteries with cells in parallel and in series also has the following key features and attributes:
1. The design minimizes the current density, resistance, and voltage drop in the busbars and interconnects of the design as a result of a number of features including one or more of the following:
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- a. The direction of current flow is kept parallel between cells connected in parallel and from parallel array to parallel array as the battery voltage is increased by the series connections of these arrays.
- b. The current path between the series connects is minimized by stacking cells so the current flow is through the thickness of the interconnect rather than through the cross-section of a loner interconnect.
- c. This approach eliminates the increase in current that occurs when individual cells are connected in parallel and the current is collected at the ends of the array. This approach minimizes the resistance, voltage drop, and temperature rise in the busbar-interconnect network. The temperature of the busbar-interconnect will be more uniform due to the uniformity of current density in the network. Lower energy losses through the busbar-interconnects lessens heat into the cells.
- d. The terminal (collector) busbars, which collect the current at the positive and negative terminals, can be designed with the appropriate cross-section to maintain the current density and temperature as the total current increases.
2. This design allows fusing to be designed integrally into the busbar connections between cells because of the parallel direction of current flow between cells connected in series. The busbar cross-section between cells in parallel can be designed to conduct normal balancing current between cells, but to act as a fuse in safety situations, i.e., when a single cell shorts either from an internal short or penetration of an external mechanical element (a nail), where very high currents will flow from adjacent cells to the shorted cell.
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- a. Activation of the fuses around the shorted cell will electrically isolate the cell and prevent the influx of high currents that could push the cell into thermal runaway.
- b. Isolation of the cell could allow continued use of the battery, thereby increasing the fault-tolerance of the system.
3. The design of the busbar and interconnect allows parallel arrays of cells or blocks, i.e. 6, 8 or more cells in parallel building block units, to be connected in parallel and in series by mechanical connections.
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- a. The mechanical interconnection of blocks simplifies assembly and maintenance of the system.
- b. Terminals of the individual cells can be designed to facilitate these mechanical interconnections. Spring loaded connections would be one approach to maintain contacts in automotive environments with vibration and shock.
- c. Scaleabilty is enhanced because of: 1) the parallel flow of current, i.e., current density in interconnects and the busbar does not change with the number of cells in parallel and 2) fusing at the cell level for protection from in-rush currents in the event that a single cell develops a short.
4. The design can be further enhanced by the incorporation of circuitry in the busbar-interconnect network. Circuitry additions could include:
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- a. Wiring to sense voltage.
- b. Sensors for monitoring temperature and stress on can surfaces. The latter can provide a measure of changes in cell thickness.
- c. Information from voltage, temperature, and other sensors could be collected on a built-in Canbus or other communications network.
The teachings of all patents, published applications and references cited herein are incorporated by reference in their entirety.
The invention generally is directed to a battery cell connector, and interconnect board for connecting a plurality of cells, a battery block system and a battery system for use with secondary (rechargeable) batteries, such as lithium ion, nickel cadmium, nickel-metal hydride and lead acid batteries. The various embodiments of the invention facilitate convenient assembly of multiple batteries, blocks of batteries, battery modules and systems that enable monitoring of subunits of the battery systems, such as individual blocks or modules of the battery system, and simplified removal and replacement of blocks and modules, as necessary, when monitoring indicates that such replacement is necessary.
As defined herein, a “battery block,” is a collection of cells constrained together in a predetermined orientation.
Also, as defined herein, a “battery module” is the collection of battery blocks connected together in series and/or parallel and provides for a positive and negative terminal.
In one embodiment, the invention is a battery cell connector 10, shown in
Each cantilevered arm 12 has major longitudinal axis 20. As shown in the embodiment of
Bridge 22 links cantilevered arms 12 at base 14 of each cantilevered arm 12, and supports cantilevered arms 12 in spaced relation to each other at edge portion 18 of each base portion 14. As can be seen in
In one embodiment, cantilevered arms 12 include protrusions 24 for contacting a terminal of a battery cell. In a specific embodiment, protrusion 24 is a contact at an end of the cantilevered arm 12 distal to base portion 14. The contact has surface 26 that is raised from cantilevered arm 12. Protrusion 24 is fixed to cantilevered arm 12 or is integral to cantilevered arm 12. In one embodiment, protrusion 24 is fixed to cantilevered arm 12 by a suitable method, such as by soldering. In another embodiment, protrusion 24 of cantilevered arm 12 has corresponding depression 28 on the side of cantilevered arm 12 opposite protrusion 24.
Protrusion 30 extends within base 14 for securing battery cell connector 10 to a circuit board. As shown in
Preferably, battery cell connector 12 is of a single, continuous, electrically-conductive material. Battery cell connector 12 is formed of a suitable material. Examples of suitable materials of battery cell connecter include steel, copper or a copper alloy. An example of a suitable copper alloy is a beryllium copper alloy. In one embodiment, the material of battery cell connecter 12 is sufficient to exert a force that provides a contact interface voltage below the contact material melting voltage. As defined herein, a “contact interface voltage below the contact material melting voltage,” means that the voltage drop across the contact is not sufficient enough to cause melting of the contact material. Typically, battery cell connector 12 will exhibit a spring constant, whereby application of external pressure forcing cantilevered portions of battery cell connecter together will be opposed by a force of the cantilevered arms that will cause the cantilevered arms to their original positions after the external force directing them together has been removed. In one embodiment, the pair of cantilevered arms of the battery cell connector has a spring constant of at least 4 kgf/mm.
In one embodiment, battery cell connector 12 is plated with a suitable material. Examples of suitable plating materials include at least one member selected from the group consisting of silver, gold, tin, platinum and palladium. Alternatively, coining of alloys such as silver-nickel onto the surface may be employed.
In a specific embodiment, cantilevered arms 12 and bridge 22 have an essentially uniform cross-sectional area. In another embodiment, shown in
Typically, fusible link 42 will have a cross-sectional area less than a cross-sectional area of at least one of the pair of cantilevered arms 44 and the bridge, depending upon where fusible link 42 is placed. For example, the fusible link could be within the cantilevered arm.
In yet another embodiment, shown in
Leaf spring 56 is fixed at distal ends by tabs 74 or by interlocking with 52. Protrusions 76 are at ends of cantilevered arms 70 for contacting opposite poles of batteries electrically connected in series. Further, protrusion 80 at base 64 cantilevered arms 52, 53 is adapted to provide electrical connection of battery cell connecter 60 to circuit board 82, shown in outline in
In other embodiments, the battery cell connector includes cantilevered arms 92 that extend along major longitudinal axes that are at angles with each other. For example, as shown in
In another embodiment, shown in
As shown in
Circuit board includes slots 124 for accommodation of leaf springs of battery cell connectors, such as for leaf spring 56 of battery cell connector 50 of the invention, shown in
In one embodiment, electrically-conductive channel 116 includes or is electrically connected to a circuit that balances battery cells connected with each other, such as battery cells connected in parallel with each other through battery cell connectors 118. Optionally, circuit board 114 includes an electrical circuit at, or in electrical communication with a circuit through terminals 126, wherein the circuit indicates voltage of at least a subset of the battery cells in electrical communication with each other. In one embodiment, the electrical circuit to which circuit board 114 is linked includes a voltage-monitoring circuit. Optionally, the circuit board 114 may include parallel copper layer 117 to balance battery cells connected to battery cell connectors 118 by electrically connecting battery cell connectors 118.
Optionally, circuit board 114 also includes at least two terminals 128 located on at least one of end portions 130 of circuit board 114. A temperature circuit (thermistor) 136 is at, or is in electrical communication with circuit board 114, wherein the temperature circuit 136 indicates the temperature of at least one of the battery cells in electrical communication with circuit board 114 through battery cell connectors 118. Temperature circuit 136 may be connected to battery cell connectors 118 via electrically conductive channel 116. Terminals 128 at circuit board 114 are connected to the temperature circuit 136.
Circuit 140, represented in the circuit diagram of
As can be seen in
Second tray supports battery cells 178 of second battery block 174 at interconnect board 162, wherein battery cells 154 of first battery block 156 are connected to battery cells 178 of secondary battery block 174 in series through battery cell connectors 166.
First busbar 180 is connected to first battery block 156 opposite interconnect board 162. First busbar 180 connects the plurality of cells of first battery block 156 in parallel at one end of the first and second terminals of battery cells. First busbar 180 includes negative terminal 182 for electrically connecting the battery cells of the battery blocks interconnected by battery block system 150 to an external monitor or other system (not shown) powered by battery block system 150 of the invention.
Second busbar 186 is connected to second battery block supported 174 by tray 176 and is positioned on the opposite side of interconnect board 162 from first busbar 180. Second busbar 186 connects the plurality of cells of second battery block 174 in parallel at one of the first and second terminals of the batteries of second battery block 174. Second busbar 186 includes positive terminal 188 for connection to an external system, such as a motor or other system (not shown) powered by battery block system 150 of the invention. Positive terminal 188 includes tab 190 for monitoring voltage of batteries of the second battery block in cooperation with interconnect board 162.
Battery block system 150 may be adapted to accommodate plurality of battery cells 154 having one or more different cell types. For example, plurality of battery cells 154 may include standard 18650-type battery cells. In order to accommodate battery cells of different types, battery block system 150 may be modified to accommodate such battery cells, for example by modifying the dimensions of trays 152, 176, interconnect board 162 and busbars 180, 186 in order to properly house and connect to the terminals of a given battery cell type.
Battery block system 150 is held together by threaded screws 192, which are threaded to stringers 194 that extend through openings of busbars 180, 186, trays 152, 176 and interconnect boards 162, as shown in
For example, in another embodiment, shown in
As can be seen in
Spring plate 230 (
An electrical diagram showing the series and parallel connections of one embodiment of the battery block system, and battery system, of the invention, is shown in
As can be seen in the electrical diagram of
In another embodiment, shown in
In still another embodiment, shown in
While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
Claims
1. A battery block system, comprising:
- a) a tray for supporting a plurality of battery cells of a battery block, the first plurality of battery cells assembled within the tray, wherein first terminals of the plurality of battery cells are aligned in a first plane at a first end of the battery block and second terminals of each of the plurality of battery cells are aligned in a second plane; and
- b) an interconnect board in mating relationship with the tray, the interconnect board including a plurality of battery cell connectors, each battery cell connector including a pair of terminals on opposite sides of the interconnect board that are in electrical communication with each other.
2. The battery block system of claim 1, further including an interconnect board housing in mating relation to the interconnect board, the interconnect board housing also being in mateable relation to the tray at the first and second planes, whereby battery cells of a second battery block system can be connected in series to the battery cells of the battery block system through the battery cell connectors of the interconnect board.
3. The battery block system of claim 2, further comprising a second battery block of a second tray for supporting battery cells of a second battery block at the interconnect board, wherein the battery cells of the first battery block are connected to the battery cells of the second battery block in series through the battery cell connectors.
4. The battery block system of claim 3, further including a first bus bar connected to the first battery block opposite the interconnect board, the first bus bar connecting the plurality of battery cells of the first battery block in parallel at one of the first and second terminals, the first bus bar including a first battery system terminal.
5. The battery block system of claim 4, further including a second bus bar connected to the second battery block opposite the interconnect board, the second bus bar connecting the plurality of battery cells of the second battery block in parallel at one of the first and second terminals, the second bus bar including a second battery system terminal.
6. The battery block system of claim 5, wherein the interconnect board is a first interconnect board, and further including a third battery block and a second interconnect board interposed between the second and third battery blocks.
7. The battery block system of claim 1, wherein at least a portion of the battery cell connectors include,
- a) a pair of cantilevered arms in spaced relation to each other, each arm having a base portion and a cantilevered portion, each base portion defining an edge portion, each cantilevered portion extending from its base portion, the cantilevered portions being splayed away from each other with distance from their respective base portions; and
- b) a bridge linking the arms at the base of each arm, and supporting the arms in spaced relation to each other at the edge portion of each base portion, the base portions and the bridge together defining a U-shape in a plane that is transverse to a major longitudinal axis of at least one arm.
8. The battery block system of claim 1, wherein the interconnect board further includes a circuit board including an electrically-conductive channel, wherein at least a portion of the battery cell connectors are in electrical communication with each other in parallel through the electrically-conductive channel.
9. The battery block system of claim 8, wherein the circuit board includes at least one fusable link between at least a subset of the plurality of battery cell connectors.
10. The battery block system of claim 9, wherein the at least one fusible link electrically isolates a battery cell in response to conducting a current greater than a threshold current.
11. The battery block system of claim 1, further including an electrical circuit at, or in electrical communication with, the circuit board, that balances battery cells connected to the battery cell connectors.
12. The battery block system of claim 1, further including an electrical circuit at, or in electrical communication with, the circuit board, that indicates voltage of at least a subset of the battery cells, wherein the electrical circuit is connected to the circuit board through a busbar having a voltage monitoring tab.
13. The battery block system of claim 1, wherein the circuit board includes at least two terminals at least one of which is at an end of the circuit board.
14. The battery block system of claim 13, further including a temperature circuit at, or in electrical communication with, the circuit board, wherein the temperature circuit indicates the temperature of a at least one of the battery cells.
15. The battery block system of claim 14, wherein the temperature circuit is remote from the circuit board.
16. The battery block system of claim 15, wherein the circuit board includes a terminal connection that is connected only to the temperature circuit.
17. A battery system comprising:
- a) a first bus bar;
- b) a first tray for supporting a plurality of battery cells connected in parallel to the first bus bar at respective first terminals of the battery cells;
- c) a second bus bar;
- d) a second tray for supporting a second plurality of battery cells connected in parallel to the second bus bar at respective first terminals of the second plurality of the battery cells, each of the battery cells of the first plurality of cells being connected in series to a respective battery cell of the second plurality of battery cells, thereby enabling electrical current flow between the first and second bus bars via plural series connections between the first and second pluralities of battery cells; and;
- e) an interconnect board having a plurality of battery cell connectors that provides electrical connection between at least one pair of battery cells of the first and second pluralities of battery cells, the interconnect board further including an electrically-conductive channel connecting the plurality of battery cell connectors.
18. The battery system of claim 17, wherein the bus bar includes a base plate component, and at least one cantilevered arm extending from the base plate.
19. The battery system of claim 18, wherein the base plate and cantilevered arm are formed of a continuous material.
20. The battery system of claim 19, wherein the cantilevered arm extends away from a plane defined by the base plate component.
21. The battery system of claim 20, further including a spring plate between the base plate component and busbar, and wherein the spring plate defines spring tabs that abut, and provide, at least in part, a spring constant to the cantilevered arms.
22. The battery system of claim 17, wherein at least a portion of the battery cell connectors include,
- a) a pair of cantilevered arms in spaced relation to each other, each arm having a base portion and a cantilevered portion, each base portion defining an edge portion, each cantilevered portion extending from its base portion, the cantilevered portions being splayed away from each other with distance from their respective base portions; and
- b) a bridge linking the arms at the base of each arm, and supporting the arms in spaced relation to each other at the edge portion of each base portion, the base portions and the bridge together defining a U-shape in a plane that is transverse to a major longitudinal axis of at least one arm.
23. The battery system of claim 17, wherein the interconnect board is a first interconnect board, and further including:
- a) a third plurality of battery cells interposed between the second plurality of battery and the second busbar; and
- b) a second interconnect board connecting to each of the battery cells of the second plurality of battery cells in series with each of the battery cells of the third plurality of battery cells via a plurality of battery cell connectors, the second interconnect board including a second electrically-conductive channel connecting the plurality of battery cell connectors.
24. A battery block system, comprising:
- a) a battery block that includes a tray for supporting a plurality of battery cells, the plurality of battery cells assembled within the tray, wherein first terminals of the plurality of battery cells are aligned in a first plane at a first end of the battery block and second terminals of each of the plurality of battery cells are aligned in a second plane at a second end of the battery block; and
- b) two interconnector busbars.
Type: Application
Filed: Oct 5, 2015
Publication Date: Feb 4, 2016
Inventors: Rui Frias (East Freetown, MA), Kenneth W. Sghia-Hughes (Acton, MA), Jamison Pezdek (Boston, MA), W. Dale Robertson (Charlton, MA), Eric J. Carlson (Sudbury, MA), Phillip E. Partin (Grafton, MA)
Application Number: 14/874,662