WO2011008736A2

WO2011008736A2 - Integrated battery packaging, interconnect, and charge management system

Info

Publication number: WO2011008736A2
Application number: PCT/US2010/041796
Authority: WO
Inventors: Marc A. Annacchino
Original assignee: Parker-Hannifan Corporation
Priority date: 2009-07-14
Filing date: 2010-07-13
Publication date: 2011-01-20
Also published as: WO2011008736A3

Abstract

A battery terminal interconnection system (10) and method that receives battery terminals (16, 18) extending from a plurality of battery modules (12) and shrouds logic and electrically charged interconnections (40, 50) from the environment. A bus bar terminal interconnection panel (14) is operable to connect a plurality of batteries in any desirable configuration.

Description

INTEGRATED BATTERY PACKAGING, INTERCONNECT, AND CHARGE

MANAGEMENT SYSTEM

Related Application Data

The present application claims the benefit of the filing date of U.S. Provisional Patent Application Serial No. 61/225,373 filed July 14, 2009, which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to battery management systems for use in hybrid and battery operated vehicles and/or other devices. In particular, aspects of the present invention relate to a system and method for safe and reliable packaging of electronics for coupling a vehicle and/or other device to a plurality of battery modules.

Background

With the many hybrid vehicles being designed, there have been many attempts at packaging the battery cells needed for powering the vehicle. These battery systems generally consist of individual cells prepackaged in a module and the modules connected in series and parallel arrangements to create the high voltage DC bus needed for the vehicle. Many of these approaches involve cabling and complex interconnects for the battery management system. These traditional approaches foster reliability problems due to the sheer number of connectors involved in the system. Furthermore, these systems are mobile and, as such, are subject to vibration thereby creating the potential for fretting corrosion, and intermittent connections over time. Summary

The present invention overcomes the above deficiencies by providing a bus bar terminal interconnection panel that receives battery terminals extending from a plurality of battery modules and shrouds logic and electrically charged interconnections from the environment. The bus bar terminal interconnection panel is operable to connect a plurality of batteries in any desirable configuration. For example, the batteries may be connected in series, in parallel and/or individually as desired. Generally, a plurality of batteries each having a positive and a negative terminal are arranged in a predetermined configuration. The bus bar terminal interconnection panel is configured to mate with the plurality of terminals extending from the batteries.

Logic and charge management circuitry is generally housed within two substrates to prevent exposure of the electrical components to the environment.

One aspect of the invention relates to a battery terminal interconnection system, the system including: a first planar member, wherein the first substrate includes a front surface and a back surface, wherein a plurality of apertures formed through the front surface and the back surface, wherein each of the plurality of apertures is configured to receive an associated battery terminal from one of a plurality of associated battery modules; at least one connector coupled with respect to the first substrate and positioned to make electrical contact with at least one of the associated battery terminals when received by the plurality of apertures, wherein each of the plurality of contacts is configured to receive at least one associated battery terminal; an electrical charging circuit coupled to at least one of the plurality of contacts, wherein the electrical charging circuit is coupled between a positive terminal and a negative terminal for each of the plurality of associated battery modules; and a second substrate coupled to the first planar member, wherein the first substrate and the second substrate at least partially house the plurality of contacts and the electrical charging circuit. Another aspect of the invention relates to the electrical charging circuit being formed from independent electrical charge management circuits and each of the independent charge management circuits is coupled to one or more adjacent electrical charge management circuits in a serial manner.

Another aspect of the invention The system of clam 1 , wherein each of the independent charge management circuits is a charge balancing circuit for maintaining a voltage associated with each of the battery modules within a predetermined range. Another aspect of the invention relates each of the independent charge management circuits being coupled to one or more adjacent independent charge management circuits by one or more electrical traces.

Another aspect of the invention relates to the one or more electrical traces being formed on the back surface of the first planar member.

Another aspect of the invention relates to each of the apertures being formed in a predetermined location in the first substrate to receive one associated battery terminal from each of the plurality battery modules.

Another aspect of the invention relates to the predetermined location preventing connection to one or more associated battery modules that are improperly registered.

Another aspect of the invention relates to the second substrate including a plurality of second apertures, wherein each of the plurality of second apertures is configured to be aligned with at least one of the plurality of apertures on the first planar member.

Another aspect of the invention relates to the first substrate and the second planar being formed from a non-conductive material.

Another aspect of the invention relates to an insulative cover for covering each of the plurality of second apertures. Another aspect of the invention relates to the at least one contact and the electrical charging circuit being sealed in a housing formed at least in part by the first substrate and the second planar member.

Another aspect of the invention relates to the housing further includes a side member for coupling the first substrate and the second member. Another aspect of the invention relates to at least some of the plurality contacts being configured to form a pressure connection with at least one contact form one of the battery modules.

Another aspect of the invention relates to an array of separation plates, such that each of the plurality of associated battery modules is separated from an adjacent battery module by at least one separation plate.

One aspect of the invention relates a method for forming an integrated battery packaging, interconnect and charge management bus bar, the method including:

forming a plurality of apertures through a front surface and a back surface of a first planar member, wherein each aperture is configured to receive a battery terminal from one of a plurality of battery modules; securing at least one contact to the back surface, wherein the contact is positioned to make electrical contact with at least one of the associated battery terminals when the at least one contact is positioned over the at least one associated battery terminals; managing electrical charging of the battery modules by coupling an electrical charging circuit to the at least one contact; and

coupling a second substrate to the first planar member, wherein the first substrate and the second substrate at least partially house the at least one contact and the electrical charging circuit.

Another aspect of the invention relates to the step of managing electric charge includes coupling independent electrical charge management circuits to a positive terminal and a negative terminal for each of the plurality of battery modules. Another aspect of the invention relates to each of the independent electrical charging circuits are coupled to one or more adjacent electrical charging circuits in a serial manner. Another aspect of the invention relates to the step of managing electric charge includes maintaining a voltage associated with each of the battery modules within a predetermined range.

Another aspect of the invention relates to separating each of the plurality of battery modules with at least one separation plate.

One aspect of the invention relates to A battery terminal interconnection system, the system including: a first planar member, wherein the first substrate includes a front surface and a back surface, wherein a plurality of apertures formed through the front surface and the back surface, wherein each of the plurality of apertures is configured to receive an associated battery terminal from one of a plurality of associated battery modules; and a second substrate coupled to the first planar member, wherein the first substrate and the second substrate at least partially house at least one contact positioned to make electrical contact with at least one of the associated battery terminals when received by the plurality of apertures, wherein each of the plurality of contacts is configured to receive at least one associated battery terminal and the first substrate and second substrate at least partially house an electrical charging circuit coupled to at least one of the plurality of contacts, wherein the electrical charging circuit is configured to be coupled between a positive terminal and a negative terminal for each of the plurality of associated battery modules.

One aspect of the invention relates to a battery terminal interconnection bus bar panel, the panel including: a housing formed from at least a first substrate and a second substrate, wherein the first substrates includes a plurality of apertures extending through the first substrate and at least some of the plurality of apertures are configured to receive an associated battery terminal from one of a plurality of associated battery modules; a plurality of connectors housed at least partially within the housing and positioned with respect to the first substrate to receive the associated batteries from the plurality of associated battery modules; and an electrical charging circuit housed within the housing and coupled to at least one of the plurality of connectors, wherein the electrical charging circuit is configured to be coupled between a positive terminal and a negative terminal for each of the plurality of associated battery modules.

Another aspect of the invention relates to the electrical charging circuit being formed from independent electrical charge management circuits and each of the independent charge management circuits is coupled to one or more adjacent electrical charge management circuits in a serial manner.

Another aspect of the invention relates to each of the independent charge management circuits being a charge balancing circuit for maintaining a voltage associated with each of the battery modules within a predetermined range.

Another aspect of the invention relates to each of the independent charge management circuits is coupled to one or more adjacent independent charge

management circuits by one or more electrical traces.

Brief Description of the Drawings

Embodiments of this invention will now be described in further detail with reference to the accompanying drawings, in which:

FIG. 1 is a perspective of an exemplary system in accordance with aspects of the present invention.

FIG. 2 is a top view of a plurality of exemplary battery modules in accordance with aspects of the present invention.

FIG. 3 is a plan view of exemplary battery separators in accordance with aspects of the present invention.

FIG. 4 is a cross-section view of an exemplary first substrate of bus bar terminal interconnection panel in accordance with aspects of the present invention. FIG. 5 is a plan view of the exemplary bus bar terminal interconnection panel in accordance with aspect of the present invention.

FIG. 6 is a plan view of rear surface of first substrate in accordance with aspects of the present invention.

FIGs. 7 and 8 are perspective views of the battery charge management system and wiring bus connection in accordance with aspects of the present invention.

FIG. 9 is a cross-section view of an exemplary second substrate of bus bar terminal interconnection panel in accordance with aspects of the present invention.

FIG. 10 is an exploded view of an exemplary battery module assembly in accordance with aspects of the present invention.

FIG. 11 is a perspective view of an exemplary battery module assembly having a cover lifted and side covers removed in accordance with aspects of the present invention.

Detailed Description of Embodiments

Referring to FIG. 1, a system 10 in accordance with aspects of the present invention is illustrated. The system 10 includes a plurality of batteries 12 coupled to a bus bar terminal interconnection panel 14 for use in a hybrid vehicle (V) or other battery operated device, for example.

Referring to FIG. 2, the batteries 12 are shown forming a bank of batteries (B) of the type used for hybrid vehicles. The batteries 12 may be any type of battery. For example, the batteries may be 12V batteries of a standard type. For example, the batteries may be a NiMH, NiCD, NiZN, Lead Acid, Advance Lead Acid, Zinc-Bromide,

Lithium Polymer, Li-ion, NaNiCI, Zinc-Air, Vanadium Redox batteries. In general, each battery 12 has a positive terminal 16 and a negative terminal 18. The battery 12 may include additional terminals. For example, one or more batteries 12 may also include a temperature terminal for providing information relating to the internal temperature or environmental temperature of the battery.

The plurality of batteries 12 may be placed in a predetermined configuration. For example, the batteries may be arranged in a matrix formation. As shown in FIG. 2, the batteries 12 may be configured in a single layer of 2 (rows) x 5 (columns) arrangement. One of ordinary skill in the art will appreciate that the matrix representation of FIG. 1 is exemplary and any and all configurations are within the scope of the present invention. For example, the batteries may be layered (e.g., stacked on one another (multiple layers) or spaced apart in a predetermined manner and the number of batteries may be fewer or greater than those shown in the attached figures.

The batteries 12 may be separated from each other by battery separation plates 20, 22, as shown in FIGs. 2 and 3. In the embodiment illustrated in FIGs. 2 and 3, the separation plates 20, 22 may mate through slots 24 formed in the bodies of the plates 20, 22 to form a plurality of receptacles 33 that isolate the batteries 12 from each other. The battery separation plates 20, 22 may be fabricated out of a simple insulator, such as a glass filled polyester or a non-conductive composite (e.g.Rosite^®), or any other suitable material. The battery separation plates 20, 22 may be removably secured to the vehicle to prevent displacement of the pluralities of batteries 12 during operation of the vehicle. One of ordinary skill in the art will readily appreciate that the size and shape of the separation plates may vary on a wide variety of factors, including the size, shape and configuration of the battery bank (B), for example.

The batteries 12 are electrically connected in series by a bus bar terminal interconnection panel 14. Referring to FIG. 4, the bus bar terminal interconnection panel 14 includes a first substrate 30 having a front surface 32 and a back surface 34. The first substrate 30 may comprise any desirable material. In one embodiment, the first substrates a printed circuit board or other non-conductive material. As state above, the bus bar terminal interconnection panel 14 may be configured for connecting the batteries 12 in any desirable electrical configuration.

As shown in FIGs. 4 and 5, the substrate 30 includes a plurality of apertures 36 (also may be referred to herein as voids) that may be formed through the front surface 32 and the back surface 34, wherein each of the plurality of apertures 36 is configured to receive an associated battery terminal (e.g., battery terminals 16, 18) from one of a plurality of associated battery modules. Generally, the apertures 36 are formed in a predetermined configuration to properly align with the bank (B) of battery modules 12. In another embodiment, the bank (B) of battery modules 12 is configured to register each battery module 12 within the bank (B) of batteries. As used herein, registration generally prevents connecting the bus bar terminal interconnection panel 14 to one or more batteries that are misaligned (e.g., the battery does not have the desired terminals in the proper location), for example.

Referring to FIG. 6, at least one contact 40 (also may be referred to herein as a connector) is coupled with respect to the first substrate 30 and positioned to make electrical contact with at least one of the associated battery terminals when received by the plurality of apertures 36. Each of the contacts 40 is configured to be coupled to at least one associated battery terminal (e.g., battery terminals 16, 18). Generally, each contact 40 is coupled to a negative terminal of one battery and to the positive terminal of one or more adjacent batteries. For example, the connector 40A is configured to be coupled to the negative terminal of battery 12A and the positive terminal of battery 12B, as set forth in Figure 6. When each of the batteries is coupled in such a manner, this is referred to as a serial connection. The contacts 40 may be any desired type and size. In one embodiment, the contacts 40 have an "M" shape as illustrated in FIG. 7. When the battery terminals are inserted into the plurality of apertures 36, the contact 40 may impart a compressive force to ensure engagement contact between the bus bar terminal interconnection panel 14 and the plurality of batteries 12 during normal operation. One skilled in the art will appreciate that the contacts 40 may take a wide variety of forms and may be configured to extend through one or more surfaces of the first substrate 30 or may be housed fully within the first planar member, for example.

Referring to FIG. 8, an electrical charging circuit 50 may be coupled to at least one of the plurality of contacts 40. The electrical charging circuit 50 may be coupled between a positive terminal 16 and a negative terminal 18 for each of the plurality of associated battery modules 12. The electrical charging circuit 50 may be formed from independent electrical charge management circuits 5OA and each of the independent charge management circuits 5OA may be coupled to one or more adjacent electrical charge management circuits 5OA and/or battery terminals in a serial manner. For example, each of the independent charge management circuits 5OA is a charge balancing circuit for maintaining a voltage associated with each of the battery modules within a predetermined range. In one embodiment, the electrical charging circuit 50 is comprised of a SKI CAN-Based Battery Management System (BMS) manufactured by SK International. One of ordinary skill in the art will readily appreciate that other manufactured systems may be integrated into this embodiment, as well as other charge management methods, such as direct connected parallel methods to address one or more battery modules 12. The electrical charge management circuits 5OA may terminate in a bus connector 54 that is configured to convey electrical charge from the plurality of batteries (e.g., from the battery bank (B)) to the electrical distribution system of the vehicle and/or other device.

Referring back to FIG. 7, each of the independent charge management circuits 5OA may be coupled to one or more adjacent independent charge management circuits by one or more electrical traces 52. A portion of the electrical traces 52 may be formed on the back surface 34 of the first substrate 30. Alternatively, one or more of the traces may be formed from a conductor that is secured to the back surface 34. In one embodiment, the electrical traces 52 may be in the form of four (4) ounce weight copper traces that are operative to connect one or more of the independent charge

management circuits in series. The copper traces 52 that provide the battery

interconnects may be formed directly on a surface of the first substrate 30. One of ordinary skill in the art will appreciate that the amount of conductive material (e.g., copper) need to adequately form the traces may depend on a variety of factors, including amount of voltage and/or current to be carried by the traces, the temperature, etc. Accordingly, more or less than four (4) ounce copper traces may be used in accordance with aspects of the present invention. Referring to FIG. 9, the bus bar terminal interconnection panel 14 may include a second substrate 60. The second substrate 60 may be coupled to the first substrate 30 in such a manner that the first substrate 30 and the second substrate 60 may at least partially house the plurality of contacts 40 and the electrical charging circuit 50. The second substrate may, optionally, include apertures 66 formed through the first surface 62 and the second surface 64. The apertures 66 may be in the same configuration of the apertures 34 on the first substrate 30, for example. One or more non-conductive caps may be used to prevent elements from the environment from entering the apertures 66, when the terminal interconnection panel 14 is in use. In addition, the second substrate 60 may take the form of a resin or other coating that seals the contacts 40 and the electrical charging circuit 50 from the environment.

In addition, while aspects of the have been described and illustrated with the contacts 40 and the electrical charging circuit 50 coupled to the back side 34 of the first planar surface, one of ordinary skill in the art will appreciate that the second substrate 60 may be utilized to couple the contacts 40 and/or electrical charging circuit to front side 62 of the second planar member.

The bus bar may terminal interconnection panel 14 be formed as a sandwich of layers of interconnects and circuits, from printed circuit boards such as G10 material. For example, the first substrate 30 and second substrate 60 may be printed circuit board. In one embodiment, the contacts 40 may be manufactured from stainless steel hardware, which will hold a pressure connection from the bus bar may terminal interconnection panel 14 to the battery terminals. This can be done with a minimum of effort in fabrication with a pre-engineered bus bar terminal interconnection panel 14. In addition, the sandwich bus bar may terminal interconnection panel 14 can accommodate the components required for each battery cell balance module which is part of the overall battery management system. Accordingly, the same planar surface (e.g., printed circuit board) that provides the battery terminal interconnect can also house the mounting of the circuitry for the battery management system. The invention provides the individual batteries cells prepackaged into a battery module, a battery management system with its charging modules, interconnection of the modules, power connection and its connection to the vehicle power distribution system, for example through bus connector 54, as illustrated in FIG. 8. By using a bus bar terminal interconnection panel 14 (e.g., a single sandwich for a common substrate of G10 board with preconfigured electrical connection (e.g., copper traces 52), an efficient system is described for simultaneously accomplishing location (e.g., registering) and fixturing of the battery modules with the bus bar terminal interconnection panel 14. Thus, it is possible to have an integrated battery management system packaging and interconnects; power interconnects for multi-cell arrangements; finger safe packaging; and insulated tap off points for string voltages. This approach houses all of the integrated power and logic connectors for this type of system thereby increasing reliability and reducing drastically the cost to manufacture.

The power connections are made interstitially between the bus panel layers (e.g., first planar layer 30 and second planar layer 60), which thereby shrouds the live (e.g., electrically conductive) components from the battery pack (B) and the apertures 34 located on the first planar layer 30 act as the "recessed female" of the connector for receiving all of the battery terminals.

In addition, this assembly is dimensionally stable enough and strong enough to provide ancillary and primarily fixturing, which will work in conjunction with battery separator receptacles (e.g., battery separators 22, 24) to create a single battery module which is interconnected and safe from potential shock hazard.

Referring to FIG. 10, the battery module assembly 10 is shown in an exploded view in FIG. 1 comprising the plurality of batteries 12 (in the form of a battery bank (B)), the battery separation receptacles 34 formed by the separation plates 20, 22), the bus bar terminal interconnection panel 14, which contains the first substrate 30 and the second substrate60 combined to sandwich the battery charging circuit 50 and connectors 40. The assembly 10 further includes a housing 80 that may include a frame 82, cover 84, and side cover plates 86 and 88, and wiring bus connector 54. The frame 82 may be affixed to the vehicle or other device in a permanent manner or releasably affixed to the vehicle. The cover 84 may be opened, as illustrated in Figure 11 , to provide access to the plurality of battery modules 12. The housing 80 may be used to prevent dirt and contaminants from building up near the battery modules. In addition, the housing 80 further serves to prevent exposure to the battery modules while the vehicle is in use and/or is undergoing maintenance, for example.

It is further conceived that aspects of the present invention may include a library of individual parts, including batteries, charging modules, interconnects, etc, that may be created and an interconnect system may be configured for each different type of battery, vehicle, electrical configuration, voltage level and current level. Such library elements may be configured with a drawing program and manufactured in a conventional manner. Although the principles, embodiments and operation of the present invention have been described in detail herein, this is not to be construed as being limited to the particular illustrative forms disclosed. They will thus become apparent to those skilled in the art that various modifications of the embodiments herein can be made without departing from the spirit or scope of the invention.

Claims

CLAIMS What is claimed is:

1. A battery terminal interconnection system (10), the system including: a first substrate (30) including a front surface (32) and a back surface (34), the first substrate having a plurality of apertures (36) extending through the front surface and the back surface and each of the plurality of apertures is configured to receive an associated battery terminal (16, 18) from one of a plurality of associated battery modules (12);

at least one contact (40) supported with respect to the first substrate and operatively positioned to make electrical contact with at least one of the associated battery terminals when received by the plurality of apertures, wherein the at least one contact is configured to receive at least one associated battery terminal; and

an electrical charging circuit (50) coupled to the at least one contact, wherein the electrical charging circuit is coupled between a positive terminal (16) and a negative terminal (18) for each of the plurality of associated battery modules.

2. The system of claim 1 , further including a second substrate (60) coupled to the first planar member, wherein the first substrate and the second substrate at least partially house the at least one connector and the electrical charging circuit.

3. The system of any one of claims 1-2, wherein the electrical charging circuit is formed from independent electrical charge management circuits (50A) and each of the independent charge management circuits is coupled to one or more adjacent electrical charge management circuits in a serial manner.

4. The system of clam 3, wherein each of the independent charge management circuits is a charge balancing circuit for maintaining a voltage associated with each of the battery modules within a predetermined range.

5. The system of claim 4, wherein each of the independent charge management circuits is coupled to one or more adjacent independent charge management circuits by one or more electrical traces (52).

6. The system of claim 5, wherein the one or more electrical traces are formed on the back surface of the first planar member.

7. The system of any one of claims 1-6, wherein each of the apertures is formed in a predetermined location in the first substrate to receive one associated battery terminal from each of the plurality battery modules.

8. The system of claim 7, wherein the predetermined location prevents connection to one or more associated battery modules that are improperly registered.

9. The system of any of claims 2-8, wherein the second substrate includes a plurality of second apertures (66), wherein each of the plurality of second apertures is configured to be aligned with at least one of the plurality of apertures on the first substrate.

10. The system of any one of claims 1 -9, wherein the first substrate and the second substrate are formed from a non-conductive material.

11. The system of any one of claims 9-10, further including insulative covers for covering each of the plurality of second apertures.

12. The system of any one of claims 1-11, wherein the at least one contact and the electrical charging circuit are sealed in a housing formed at least in part by the first substrate and the second substrate.

13. The system of claim 12, wherein the housing further includes at least one side substrate (86, 88) for coupling the first substrate and the second substrate.

14. The system of any of claims 1-13, wherein at least some contacts are configured to form a pressure connection with at least one terminal from one of the battery modules.

15. The system of any one of claims 1-14, wherein the first substrate and the second substrate are formed from a non-conductive material.

16. The system of any one of claims 1-15, further including an array of separation plates (20, 22), such that each of the plurality of associated battery modules is separated from an adjacent battery module by at least one separation plate.

17. A method for forming an integrated battery packaging, interconnect and charge management bus bar panel (14), the method comprising:

forming a plurality of apertures (36) through a front surface (32) and a back surface (34) of a first substrate (30), wherein each aperture is configured to receive a battery terminal (16, 18) from one of a plurality of battery modules (12);

securing at least one contact (40) to make electrical contact with at least one of the associated battery terminals when at least some of the plurality of apertures are positioned over the at least one associated battery terminals;

managing electrical charging of the battery modules by coupling an electrical charging circuit (50) to the at least one connector and at least one of the plurality of battery modules; and

coupling a second substrate (60) to the first planar member, wherein the first substrate and the second substrate at least partially house the at least one connector and the electrical charging circuit.

18. The method of claim 17, wherein the step of managing electric charge includes coupling independent electrical charge management circuits (50A) to a positive terminal (16) and a negative terminal (18) for each of the plurality of battery modules.

19. The method of claim 18, wherein each of the independent electrical charging circuits are coupled to one or more adjacent electrical charging circuits in a serial manner.

20. The method of any one of claims 17-19, wherein the step of managing electric charge includes maintaining a voltage associated with each of the battery modules within a predetermined range.

21. The method of any one of claims 17-20, further including separating each of the plurality of battery modules with at least one separation plate (20, 22).

22. A battery terminal interconnection bus bar panel (14), the panel including: a housing formed from at least a first substrate (30) and a second substrate (60), wherein the first substrates includes a plurality of apertures (36) extending through the first substrate and at least some of the plurality of apertures are configured to receive an associated battery terminal (16, 18) from one of a plurality of associated battery modules (12);

a plurality of connectors (40) housed at least partially within the housing and positioned with respect to the first substrate to receive the associated batteries from the plurality of associated battery modules; and

an electrical charging circuit (50) housed within the housing and coupled to at least one of the plurality of connectors, wherein the electrical charging circuit is configured to be coupled between a positive terminal (16) and a negative terminal (18) for each of the plurality of associated battery modules.

23. The system of claim 22, wherein the electrical charging circuit is formed from independent electrical charge management circuits (50A) and each of the independent charge management circuits is coupled to one or more adjacent electrical charge management circuits in a serial manner.

24. The system of clam 23, wherein each of the independent charge management circuits is a charge balancing circuit for maintaining a voltage associated with each of the battery modules within a predetermined range.

25. The system of claim 24, wherein each of the independent charge management circuits is coupled to one or more adjacent independent charge management circuits by one or more electrical traces (52).