Modular Li-ion Battery System for Forklifts

Abstract

To provide a rechargeable battery assembly that can replace lead acid batteries for forklifts. [Solution] The rechargeable battery assembly includes multiple removable battery modules. The battery modules can be individually recharged and interchangeable. The handles for each module are foldable and located at the top of the entire assembly for easy access during removal. Each battery module has an integrated battery monitoring system (BSS). A battery operating system supervisor (BOSS) module processor functions as the battery management system for all battery modules. The BOSS module provides permission to the battery modules, allowing them to connect and disconnect from the busbars at the appropriate times to prevent electrical problems.

Description

[Technical Field]

[0001] Claiming priority to an earlier application

[0001] This application claims the benefit of previously filed, co-pending U.S. Provisional Patent Application No. 62 / 532,199, filed July 13, 2017, and previously filed, co-pending U.S. Provisional Patent Application No. 62 / 692,702, filed June 30, 2018. The entire disclosures of U.S. Provisional Patent Application No. 62 / 532,199 and U.S. Provisional Patent Application No. 62 / 692,702, including claims and drawings, are incorporated herein by this reference as if set forth in their entirety.

[0002] Background of the Invention 1. Field of the Invention

[0002] The present invention relates to battery-powered industrial trucks and their rechargeable batteries, as well as related aspects of their use. More specifically, the present invention relates most directly to Class I forklifts, but may also find application in connection with other classes of battery-powered industrial trucks. [Background technology]

[0003] 2. Description of Related Technology Before reviewing the specific field of the present invention, it may be helpful to consider some background information about rechargeable lithium-ion batteries in general. Rechargeable lithium-ion batteries were developed in the 1970s, and even then, many of their benefits and potential industrial applications were well understood. While initially slow to reach commercial use, by the 1990s they had gained much wider popularity. Rechargeable lithium-ion batteries are primarily characterized by reference to the type of lithium intercalation compound used as the positive electrode of their battery cells. While lithium metal oxides have been the most successful in industrial use, with lithium cobalt oxide (LiCoO or LiCoO2) being the most popular, their use has been fraught with drawbacks, particularly with regard to thermal runaway and related safety concerns. As development progressed, substantial improvements were realized by doping the lithium positive electrode-forming material with additional metals (e.g., nickel, manganese, aluminum, etc.). Various innovations have also involved the use of core-shell particle cathodes, improved anodes, and solid lithium polymer electrolytes; still other innovations have led to smaller cathode particle sizes, increased electrode surface areas, and other improvements in total battery capacity.

[0004]

[0004] Today, the most popular lithium-ion batteries are of the LCO type, most notably lithium-nickel-cobalt-aluminum-oxide (NCA or LiNiCoAlO2) and lithium-nickel-manganese-cobalt-oxide (NMC or LiNiMnCoO2). Alternative cathode compositions include other lithium metal oxides, such as lithium manganese oxide (LMO) and lithium manganese-nickel oxide (LMNO), and other lithium-ion chemistries can also be considered for specific needs. For example, lithium metal phosphates have also long been available, theoretically offering improved cycle times, shelf life, and safety, but other performance tradeoffs have made them less popular among manufacturers than LCO types. One specific type of lithium metal phosphate, lithium iron phosphate (LFP or LiFePO4), has long been an available type of rechargeable lithium-ion battery, but offers various advantages and disadvantages compared to NCA, NMC, and other LCO batteries. NCA, NMC, and other LCO batteries have generally been weighed against the use of LFP.

[0005]

[0005] As a particularly successful example of lithium-ion battery implementation in other fields, Tesla, Inc. popularized the use of NCA batteries for its Model S electric vehicle. While NCA batteries perform well due to their high energy density, they have relatively low thermal stability and tend to have a thermal runaway temperature of approximately 150°C. Tesla's battery manufacturing method helps balance benefits and risks by safely interconnecting hundreds of smaller battery cells in much larger assemblies to achieve the required energy density while minimizing the risk of arcing and overheating. Within the larger assembly, hundreds of smaller battery cells are connected in groups, each containing many parallel cells connected by wire bonds to adjacent bus bars. The bus bars of those groups are then joined in series to create a much larger assembly that meets the power demands of the electric vehicle. This method permanently connects each terminal of each cell to the overall assembly. However, rather than using traditional methods of soldering, resistance spot welding, or laser welding, Tesla uses ultrasonic vibration welding, and the wire joints are made of low-resistance wire that allows the expected current to pass without significant overheating. Each wire joint is only about one centimeter long, with one end bonded to a battery terminal and the other end bonded to an aluminum busbar conductor section, which is then electrically coupled to other busbars in the circuit. In the event of an overcurrent due to a short circuit or the like, each wire joint can act as a fuse that blows to prevent excessive overheating.

[0006]

[0006] LFP batteries tend to have lower energy densities than NCA and NMC batteries, but have also long been known for their superior thermal stability. Thermal runaway in LFP batteries typically does not occur until approximately 270°C, thereby improving safety and reducing the likelihood of catastrophic complete failure. LFP batteries are also more stable under short-circuit or overcharge conditions and do not readily decompose at high temperatures. Other verifiable advantages include greater power density (i.e., they can deliver higher power levels per unit volume) and significantly increased cycle life compared to lead-acid batteries. While typical lead-acid batteries have an average lifespan of 300 cycles with a 20% degradation of stored charge, LFP batteries can last in excess of 2000 cycles with the same 20% degradation of stored charge.

[0007] Meanwhile, in the field of the present invention, despite the long-term availability of common lithium-ion batteries, Class I forklifts still typically operate with lead-acid batteries. One reason for this is that many forklifts (especially Class I forklifts) require substantial counterbalance for safe use. Forklift lead-acid batteries typically weigh over 1,000 pounds, and therefore many forklifts have been designed to use the weight of lead-acid batteries to maintain stability. However, their large weight also presents many challenges, especially in the context of removing, replacing, and otherwise handling lead-acid batteries. Because workers cannot safely lift such a weight, special hoists and battery replacement equipment are required, resulting in additional expense and floor space. Naturally, this also creates the risk of back injuries and the like.

[0008]

[0008] Beyond weight-related risks, due to the corrosive nature of sulfuric acid, lead-acid batteries also present a risk of eye, lung, skin, and clothing damage to personnel handling them. Additionally, hydrogen gas is typically released during battery recharging, which can explosively combine with oxygen and accelerate corrosion of surrounding components. Consequently, lead-acid batteries require special safety protocols, and special care must be taken to ensure adequate ventilation around forklifts and their recharging stations to combat hydrogen and sulfur odors.

[0009]

[0009] Furthermore, forklift lead-acid batteries are expensive in terms of time, space, and inventory. Forklift lead-acid batteries typically last only about six hours of continuous use before requiring an eight to nine hour recharge. Forklift lead-acid batteries also require long maintenance times and have a much shorter life cycle compared to lithium-ion technology. Forklift lead-acid batteries also tend to require large areas in warehouses dedicated to charging and maintenance, and each forklift typically requires two spare batteries for a facility operating 24 hours a day.

[0010]

[0010] As a result of many of the above-mentioned and other reasons, people have long considered the use of forklift lithium-ion batteries as an alternative form of battery, but the resulting attempts have been, at best, ineffective, and many of the challenges of the characteristically heavy forklift lead-acid batteries still plague the forklift industry.

[0011]

[0011] Thus, despite the well-known characteristics and long-term availability of rechargeable LFP and other lithium-ion battery technologies, there remains a substantial and long-felt unmet need for improved battery technology in the forklift industry. Co-owned U.S. Provisional Patent Application No. 62 / 532,199 is incorporated herein by reference in its entirety. Summary of the Invention

[0012] Summary of the Invention The innovations of the present invention improve the safe and reliable operation of conventional electric forklifts in various ways, in part by enabling forklift rechargeable lithium-ion batteries to be replaced with the forklift lead-acid batteries for which such forklifts are conventionally adapted for use. Many embodiments of the present invention involve a rechargeable battery assembly that is the size of a forklift battery but includes multiple removable battery modules. The removable battery modules can be individually recharged and interchangeable with one another. Each such battery module is self-contained, equipped with an integrated handle for easy removal from the external assembly, and preferably sized or otherwise adapted for manual removal by forklift operators and maintenance personnel. Thus, each individual battery module can be selectively removed for recharging or replacement with a fully charged replacement module.

[0013]

[0013] A preferred adaptation is such that when an operator or maintenance person desires to recharge the entire assembly, the entire assembly can be removed and recharged in the same manner as conventional forklift lead-acid batteries, or can be left in the forklift in the preferred manner for charging the entire assembly, while alternatively, one or more of the individually removable modules can be manually removed for recharging or replacement. Aspects of the present invention further enable removal of multiple modules from a larger battery assembly to allow for its recharging or replacement while still allowing for continued operation of the forklift. Moreover, other innovative aspects of Applicant's approach allow individual battery modules and / or larger assemblies to be recharged not only with a lithium-ion charger, but also readily compatible with recharging with a conventional lead-acid battery charger.

[0014] A preferred embodiment of the larger battery assembly includes a forklift battery-sized housing with a symmetrical arrangement of individually removable and replaceable modules. Preferably, the housing contains six battery modules mounted vertically at the front of the assembly, with their electrical and data connections occurring within the housing at its rear. A preferred embodiment is double-sided, resulting in a system with two racks, six modules per rack, for a total of 12 modules. The handles of each module are foldable and oriented toward the top of the entire assembly, allowing easy access during manual removal of the corresponding module.

[0015] A preferred embodiment has battery modules secured in place using latched doors. Each battery module has a low-friction surface to ensure smooth and controlled movement during battery module release. The low-voltage connector pins incorporate an interlocking feature. The interlocking feature is wired so that three conditions must be met before the battery module can be engaged with the communication bus. These conditions include mating of the low-current connector, engagement of the enclosure rack's physical locking system, and successful linking with the communication bus. The interlocking pin loops through the physical latch of the slot into which the module is connected, so that the BOSS module knows the module is connected. Upon module insertion and latch closure, the interlocking pin is shorted by the module ground pin. This mechanism helps prevent arcing in many embodiments of the present invention. Without these related benefits, arcing could lead to an overcurrent scenario, which, in turn, risks destroying the electrical connector if proper precautions are not taken.

[0016] Each battery module has an integrated battery monitoring system (BSS). The system monitors cell health, including cell voltage, current, and temperature. During charging, the system monitors the state of charge, compensates for voltage differences, and ensures the pack remains operational if and only if the battery cells are properly balanced and within operating temperature limits. In addition, the system maintains history and information that can be communicated to the lift truck and charger via a physical CAN bus.

[0017]

[0017] The battery modules of the preferred embodiment are connected in a series and parallel combination to achieve higher voltage, higher capacity, and higher current capacity. Each battery module is self-contained and contains its own internal controller. However, there is some redundant monitoring and control performed by a secondary controller (e.g., motor controller and / or charger).

[0018] Within each module, the individual battery cells are connected using a technique comparable to Tesla's wire-bonded battery manufacturing method. However, a key difference from Tesla involves the use of LFP battery technology rather than NCA or other LCO battery technologies, as previously discussed. Among the many resulting performance differences, it is notable that in the preferred embodiment, up to four modules per enclosure rack can be removed for charging and the forklift still continue to operate (because such removal does not reduce the voltage below the overall requirement). For continued operation, the assembly requires a minimum of two 24-volt battery modules. A plastic battery tray and thermally conductive adhesive are located between the battery cells and the printed circuit board (PCB). A thermally conductive and electrically insulating adhesive is used between the upper plastic battery tray and the PCB. Additionally, the same adhesive is used between the battery cells and the upper and lower plastic battery trays. For thermal management purposes, a thermal gap filler is applied between the bottom of the battery cells and the module enclosure. [Brief explanation of the drawings]

[0019] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1]

[0019] Figure 1 shows a perspective view of a preferred embodiment of the disclosed assembly with the door closed. The assembly includes an enclosure rack containing six separable battery modules. [Figure 2]

[0020] FIG. 1 shows a side view of a Class I forklift in a configuration representative of the prior art, showing that the forklift contains a conventional forklift lead-acid battery in an openable battery compartment, with arrows conceptually illustrating the relationship of its counterweight, the weight of its load, and the resulting center of mass compared to the fulcrum reaction force generated by the forklift's front wheels. [Figure 3]

[0021] 2 is a side view of a Class I forklift without the conventional forklift lead-acid battery of FIG. 1, but instead incorporating a rechargeable battery assembly in accordance with the teachings of the present invention. [Figure 4A]

[0022] 13 shows the engagement and disengagement of the slam latch from the housing. [Figure 4B]

[0023] Shows the pin lock feature on the door that holds the battery module in place. [Figure 5A]

[0024] 1 shows the enclosure door in a half-open position and the location of the door pin. [Figure 5B]

[0024] The location of the enclosure door and door pin is shown in a half-open position. [Figure 6A]

[0025] Shows the location of the enclosure door and door pin in the fully open position. [Figure 6B]

[0025] The location of the housing door and door pin is shown in the fully open position. [Figure 7A]

[0026] Shows the process of removing the module from the enclosure once the door is fully open. [Figure 7B]

[0026] The process of removing the module from the enclosure is shown once the door is fully open. [Figure 8A]

[0027] 13 illustrates disengagement of a slam latch from a housing in an alternative embodiment. [Figure 8B]

[0027] Figure 1 illustrates the disengagement of a slam latch from a housing in an alternative embodiment. [Figure 9A]

[0028] Shows the enclosure door in a half-open position and module pin locations. [Figure 9B]

[0028] Shows the housing door in a half-open position and the location of the module pins. [Figure 10A]

[0029] Shows the enclosure door in the fully open position and module pin location. [Figure 10B]

[0029] Shows the housing door in the fully open position and the location of the module pins. [Figure 11A]

[0030] Shows the process of removing the module from the enclosure once the door is fully open. [Figure 11B]

[0030] The process of removing the module from the enclosure is shown once the door is fully open. [Figure 12]

[0031] 1 shows a rear view of the housing with the module inserted. [Figure 13]

[0032] 1 shows a rear and side perspective view of the housing with the module inserted. [Figure 14]

[0033] 1 shows a rear view of the battery module. [Figure 15]

[0034] FIG. 2 shows a partial front view of the battery module. [Figure 16]

[0035] FIG. 2 shows a perspective view of the inside of the battery module. [Figure 17]

[0036] FIG. 2 shows an internal top view of the battery module. [Figure 18]

[0037] 1 shows a cross-sectional view of an individual battery cell within a module. [Figure 19]

[0038] A schematic diagram showing six battery modules connected in parallel to an enclosure rack is shown. [Figure 20]

[0039] 15 is an elevational view of an alternative embodiment rechargeable battery assembly 220. Assembly 220 is a variation incorporating eight separable battery modules 330, and FIG. 15 shows an outer housing rack 300 and half of those eight battery modules 330 (i.e., modules 330a-330d) operatively disposed therein. [Figure 21]

[0040] 22 is a mid-sectional view of an alternative embodiment rechargeable battery assembly 220 showing the remaining half of the outer housing rack 300 and the battery modules 330 operatively disposed therein (i.e., the half not shown in FIG. 21, i.e., modules 330e-330h), the viewing surfaces of FIG. 22 being numbered like cross section 4-4 of FIG. 23. [Figure 22]

[0041] FIG. 2 is a partially cutaway isometric perspective view of an alternative embodiment rechargeable battery assembly 220 having its battery module 330 operatively disposed therein, with most of the top wall 303 and a portion of the central wall 350 partially cut away to reveal some of its details. [Figure 23A]

[0042] FIG. 6 is a partial isometric perspective view focusing on one of the individual battery modules 330 (i.e., module 330a) of an alternative embodiment, with module 330a in its operably engaged position within bay 307a of housing rack 300, with a large portion of the housing cut away to show module 330a and its removability in the direction of arrows 608, 609. [Figure 23B]

[0043] 10 is a simplified isometric view showing the rear of an individual battery module 330a of an alternative embodiment, the battery module 330a resting on elemental representations of the slides 610, 611 of the enclosure rack assembly 300. FIG. [Figure 24A]

[0044] FIG. 10 is an isometric view of the interior top view of an alternative embodiment battery module 330 and its rear connections 400, 401, 402. [Figure 24B]

[0045] 24B is an isometric view of the interior underside of the alternative embodiment battery module 330 of FIG. 24A and its rear connections 400, 401, 402. FIG. [Figure 25]

[0046] 24 is a top view of elements of an alternative embodiment battery module 330 showing symbolic representations of its connections and mechanisms for operable installation and removal into and from the enclosure rack 300 of FIG. 23. [Figure 26]

[0047] 9 is an exemplary schematic diagram of an alternative embodiment in which battery modules in an enclosure rack are connected in parallel and connected to an enclosure rack control system 901. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] Detailed Description of the Preferred Embodiments

[0048] The following description relates to presently preferred embodiments and should not be construed as describing limitations of the invention; instead, the broader scope of the invention should be considered with reference to the claims, which may be appended hereto or added or amended later in this or related applications. Unless otherwise indicated, the terms used in these descriptions should generally be understood to have the same meaning as would be understood by one of ordinary skill in the art. It should also be understood that the terms used are generally intended to have the ordinary meaning as would be understood within the context of the relevant technical field, and that the terms generally should not be limited to formal or ideal definitions, or to conceptually encompassing equivalents, unless and only to the extent that the specific context clearly requires.

[0021]

[0049] For the purposes of these descriptions, some shorthands should be universally understood unless made clear in the specific context of this specification or a particular claim. The use of the term "or" should be understood as referring to alternatives, but is generally used to mean "and / or" unless there is an explicit indication that only alternatives are referred to, or unless the alternatives are inherently mutually exclusive. When referring to a value, the term "about" can be used to indicate an approximate value (generally a value that can be read as being that value plus or minus one-half of that value). "A" or "an" and the like can mean "one or more," unless expressly indicated otherwise. Such a "one or more" meaning is particularly intended when referred to in conjunction with open terms such as "having" or "comprising," including. Similarly, "another" object can mean at least a second or more objects.

[0022] Preferred Embodiments

[0050] Although the following description primarily relates to preferred embodiments and may occasionally reference several alternative embodiments, it should be understood that many other alternative embodiments fall within the scope of the present invention. Those skilled in the art should understand that the techniques disclosed in these examples are believed to represent techniques that work well in practicing the various embodiments and, therefore, can be considered to constitute preferred modes for those practices. However, in light of this disclosure, those skilled in the art should also understand that many modifications can be made to the disclosed embodiments while still obtaining equivalent functions or results without departing from the spirit and scope of the present invention.

[0023] Housing rack and battery module interface design

[0051] FIG. 1 shows a perspective view of the preferred embodiment 10, showing the front of the enclosure rack ("enclosure") 100. The enclosure 100 is preferably constructed of steel or another material suitable for providing strength and stability. The preferred embodiment 10 has six vertically arranged battery modules ("modules") 200. When installed within the enclosure 100, each module 200 is secured in place by a door 110 with a slam latch 115. The slam latch 115 is attached to the front of each door 110. The doors 110 prevent the modules 200 from sliding back and forth, thereby preventing loose contact. Each door 110 extends from the top of the enclosure 100 to the exposed lower sheath 202 of the module 200. Additionally, dividers 101 are secured to the enclosure 100 and are located between each module 200 to prevent side-to-side movement. A total of five dividers 101 are secured to the enclosure 100. Each of the doors 110 is cut out to allow visibility of the display panel 225 on each module 200. The display panel 225 is illuminated using LEDs to indicate the status of each module 200. Further details regarding the display panel 225 are shown in FIG. 15 and described later herein.

[0024] Typical lift trucks

[0052] FIG. 2 shows a side view of a conventional Class I electric forklift 130, representing a prior art lift truck design that may incorporate, embody, or be used with the present invention. The particular model of forklift 130 shown resembles a Caterpillar Model E6000 forklift, and is specified with a 48V battery (meeting minimum weight requirements) that is 34.4 inches long (i.e., depth from front to back) by 39.5 inches wide (i.e., lateral dimension when installed on the forklift) by 23.3 inches high. As a Class I forklift, the forklift 130 is a mobile truck equipped with a lifting assembly 131 for raising and lowering forks or other load-supporting members 132 adapted to support a load 150 thereon for the purpose of lifting, carrying, or moving the load 150.

[0025]

[0053] The load support member 132 is conventionally designed in a cantilevered fashion to support the load 150, generally extending forward of the fulcrum created by the front wheels 142 of the forklift 130, with heavier loads more likely to present a risk of tipping over of the forklift 130. Minimizing that risk of tipping over under load is therefore fundamental to the safe operation of such a forklift 130, and in line with its classification as a Class I lift truck, the weight of the load 150 (F L , indicated by arrow 151) is the total range of the counterweight load (F C , indicated by arrow 121). In other words, the weight of the load 150 (F L , indicated by arrow 151) increases with the counterweight load (F C ) must be less than the opposing torque primarily produced by the

[0026]

[0054] In the prior art, such forklifts 130 generally have a counterweight load (F C) and Class I forklifts are generally designed accordingly. Such forklift designs generally incorporate structure for safely supporting the weight of the forklift battery 160 within a battery compartment 122 of a particular length (i.e., depth), width, and height. The battery compartment 122 is generally defined in part by a removable or openable panel or the like that partially or completely contains and defines the space for the forklift battery 160 therein. In the case of the forklift 130 shown, for example, the battery compartment 122 is defined in part by a seat assembly 135 and partial side panels 136. The seat assembly 135 is typically located above the forklift battery 160 but has a releasable latch that allows it to be manually pivoted upward and away from the forklift battery 160 to allow the operator access to the forklift battery 160 or its compartment 122. Similarly, a panel 136 or other structure may be provided to help enclose and define the battery compartment 122, and the panel 136 may also be removable or openable to allow fuller access to the battery compartment 122, such as for purposes of checking or replacing the forklift battery 160 therein. The forklift 130 also has positive and negative conductors for removably connecting the forklift's electrical circuitry to corresponding terminals on a conventional forklift battery 160.

[0027]

[0055] The forklift uses a fulcrum (indicated by arrow 91) created between the front wheels of the forklift and the floor surface 90 below. L ) is generated by the opposite forklift counterweight (F C) is exceeded, the forklift 130 will tip forward onto the load 150, creating a dangerous situation. The location of the center of gravity 161 depends in part on whether the forklift is loaded. When the forks 171 are raised while carrying the load 150, the center of gravity 161 naturally shifts toward the front and upward of the forklift.

[0028] Rechargeable Lithium-ion Battery Assembly

[0056] FIG. 3 shows the same representative Class I electric forklift 130 as shown in FIG. 2 , but with a preferred rechargeable battery assembly 230 according to the teachings of the present invention operably installed in the battery compartment 122 instead of the conventional forklift lead-acid battery 160 of FIG. 1 . In contrast to the conventional lead-acid battery 160, the rechargeable assembly 230 includes a plurality of separable battery modules 200, preferably an even number (six in the illustrated embodiment), each of which contains a number of lightweight lithium-ion battery cells therein. Most preferably, these many battery cells are of the LFP type. In contrast to the shorter usage time and much longer charging time characteristic of the conventional lead-acid battery 160, the entire assembly 230 can hold an operational charge for approximately 10 hours without recharging or replacing individual modules 200, after which a recharge of approximately 60 minutes is required. Furthermore, due to their lithium-ion chemical composition, each module 200 can be repeatedly charged and cycled approximately six times as many times as the conventional lead-acid battery 160.

[0029]

[0057] Particularly for LFP chemistries, charging rates corresponding to charging times of one hour or less are often within the recommended operating limits of the cells. Additionally, the easy removal of module 200 provides opportunities for charging during breaks. For example, a driver can remove module 200 during a 15-minute break and allow for a substantial recharge during this short interval. The longer operating time of rechargeable assembly 230 compared to conventional lead-acid batteries 160 also improves workplace efficiency. With lead-acid batteries 160, a larger area is allocated for recharging. After an eight-hour work shift, lead-acid batteries 160 are removed and replaced with charged lead-acid batteries 160 for recharging. Replacing this system with rechargeable assembly 230 saves time and valuable space in the work environment.

[0030]

[0058] Another important advantage of the rechargeable assembly 230 is the lower equivalent series resistance (ESR) of LFP batteries compared to lead-acid batteries 160. Lead-acid batteries 160 have a higher ESR and consequently experience reduced performance. When these batteries 160 discharge, "voltage droop" occurs, often resulting in sluggish operation of the forklift truck under load or acceleration. In most cases, this occurs approximately six hours into the shift, requiring additional recharging per shift, thereby reducing the battery's lifespan. LFP batteries offer improved sustained performance during a shift while significantly reducing the risk of voltage droop.

[0031]

[0059] A preferred embodiment of the rechargeable assembly 230 has six battery modules 200 installed in a larger housing rack 100. The modules 200 are preferably arranged in two symmetrical groups, with half removable from one lateral side of the housing rack 100 and the other half removable from the other lateral side of the housing rack 100. The complete assembly 230 preferably contains two sets of six modules 200 arranged back-to-back and vertically oriented, with their fronts exposed on either side of the forklift when the removable panels 136 are removed or opened. Alternate embodiments may have different locations or quantities of battery modules comprising the housing rack 100.

[0032]

[0060] Once sized, weighted, and otherwise adapted to closely match a conventional battery 160, the height "H," depth "D," and width (the dimensions perpendicular to FIG. 2 ) of the assembly 230 are substantially the same as those of a conventional forklift battery 160 intended for use in the forklift 130. Thus, the assembly 230 can be described as "forklift battery-sized." Its forklift battery-sized characteristics allow the assembly 230 to safely fit into the same battery compartment 122 as the conventional battery 160, for the forklift 130 as shown. Additionally, the preferred embodiment of the rechargeable battery assembly 230 is weighted with a centrally oriented steel plate at its base integrally secured to its underside 304 to meet the minimum (and maximum) weight requirements for batteries used in the forklift 130, as specified by the manufacturer of the forklift 130.

[0033]

[0061] 3, the lithium-ion battery assembly 230 is adapted to fit into the Caterpillar E6000 forklift battery compartment 122 for use in place of the conventional lead-acid battery 160. More specifically, for the E6000, the lithium-ion battery assembly 230 fits approximately into the dimensions of 34.4 inches long (i.e., depth from front to back) by 39.5 inches wide (i.e., lateral dimension when installed on the forklift 130) by 23.3 inches high, and the assembly 230 has a minimum weight of 3100 pounds, preferably with a 50 pound margin over the manufacturer's specified minimum battery weight requirement.

[0034]

[0062] Those skilled in the art will appreciate that the size, fit, shape, and weight of different makes and models of forklifts will determine the size range for alternative embodiments intended for use with a particular make and model of forklift. The full range of sizes for Class I forklift batteries is for alternative embodiments. The range of minimum battery weight requirements for Class I electric forklifts is approximately 1,500-4,000 lbs, and is also for alternative embodiments.

[0035]

[0063] A preferred embodiment is contemplated to allow removal of four modules 200 in each enclosure rack 100 for replacement or recharging while still being able to maintain operation of a forklift with two modules per rack 100. To accommodate continued operation despite the removal of one module 200, such removal does not reduce the voltage below the requirements for the forklift 130.

[0036]

[0064] While many aspects of the present invention can be realized with other types of rechargeable batteries, the preferred embodiment uses battery cells of one of the lithium-ion types. Most preferably, each module 200 of the battery assembly 230 incorporates hundreds of self-contained battery cells of the LFP (lithium iron phosphate) type. While all lithium-ion battery types can experience thermal runaway, the LFP battery cells of the preferred embodiment have a fairly high thermal runaway temperature of 270°C, which is substantially higher than the runaway temperature of more conventional lithium-ion battery cells, such as NCA or other LCO cells (which typically have a thermal runaway temperature of approximately 150°C). While the preferred embodiment uses LFP batteries, it should be understood that some aspects of the present invention can be realized through the use of other types of rechargeable lithium-ion battery cells. For example, for some embodiments of the present invention, alternative compounds are contemplated to include, without limitation, lithium cobalt oxide (LiCoO), lithium manganese oxide (LiMnO, LiMnO), lithium nickel cobalt aluminum oxide (LiNiCoAlO), and lithium nickel manganese cobalt oxide (LiNiMnCoO).

[0037]

[0065] Within each battery module 200 of the preferred embodiment, multiple self-contained battery cells (preferably in the range of 160-200 cells per module 200) are connected in series and parallel combinations using wire bonding methods. Wire bonding methods use wire bonds instead of bus bars to connect the batteries. Wire bonding is achieved through ultrasonic friction welding. By interconnecting the batteries with wire bonds, the wire bonds can prevent short circuits while acting as fuses. The wire bonds are made of wire that allows the expected current to pass without significant overheating, and the wire bonds can be broken to prevent overcurrent in individual cells. In addition, FETs or other forms of conventional fuses are placed inside the battery module. If the current-carrying capacity is exceeded, the fuse opens, preventing the wire bonds from blowing due to overcurrent. Alternative embodiments of this design can connect the battery cells in parallel. In addition, alternative battery connection methods can include traditional soldering and spot welding.

[0038] Battery module removal and insertion

[0066] Turning to FIG. 4A, the disengagement of slam latch 115 from housing 100 is shown. Bottom end 116 of latch 115 is depressed to release top end 117 from engagement with housing 100. Pin 201 is permanently attached to door 110 and fits into groove 112. FIG. 4B shows hinge 111 of door 110 engaging module 200. Although not visible in FIG. 4B, door 110 has an identical pin 201 on its opposite side. Similarly, module 200 has an identical groove 112 on its opposite side. Pin 201 remains at the top of groove 112 until door 110 is opened.

[0039]

[0067] Turning to FIG. 5A, door 110 of housing 100 is shown in a half-open position. In FIG. 5A, module 200 is shown protruding from front end 102 of housing 100. In FIG. 5B, pin 113 is shown halfway up groove 112. When door 110 is opened, door 110 rotates counterclockwise about hinge 111. At the same time, pin 113 moves down groove 112 toward the bottom of module 200. It should be understood that the same mechanism simultaneously exists on the other side of module 200. When door 110 is opened, module 200 slides out of housing 100.

[0040]

[0068] Turning to Figure 6A, door 110 of housing 100 is shown in a fully open position, rotated 90 degrees from the closed position. As a result of door 110 being opened, module 200 is pulled out of housing 100 and protrudes from end 102. In Figure 6A, carrying handle 205 of module 200 is clearly visible. Carrying handle 205 is preferably bolted to module 200, but can be detached. In Figure 6B, pin 113 is shown at the bottom of groove 112, allowing module 200 to be removed from housing 100.

[0041]

[0069] 7A, the module 200 is shown removed from the housing 100 and placed on the door 110. The top of the module 200 has an upper protective sheath 203 with a cutout area for viewing the display panel 225. Once the door 110 is in the fully open position, a user can manually slide the module 200 out of the housing 100 along a track (not shown) on the door 110. The preferred embodiment 10 has low-friction slides located below each module 200. Moving to FIG. 7B, a user can manually fold the carrying handle 205 upward and lift the module 200 away from the door 110. The user can then use the carrying handle 205 to carry the module 200 to a battery charging station and replace it with another charged module 200. Preferably, the battery module 200 weighs 51 pounds or less in accordance with OSHA and other workplace standards. Replacing the module 200 requires performing the reverse of the removal procedure described above.

[0042]

[0070] 8A-11B illustrate a procedure for removing module 200 in an alternative embodiment. Turning to FIG. 8A, the disengagement of slam latch 115 from housing 100 is shown. The bottom end 116 of latch 115 is pushed down to release top end 117 from engagement with housing 100. In FIG. 8B, hinge 111' of door 110' is shown engaging module 200. Pin 201', permanently attached to module 200, fits into groove 112' of hinge 111'. Pin 201' remains at the bottom of hinge 111' until door 110' is opened.

[0043]

[0071] Turning to FIG. 9A, the door 110' of the housing 100 is shown in a half-open position. In FIG. 9B, the pin 201' is shown halfway up the groove 112'. When the door 110' is opened, the hinge 111' rotates counterclockwise around the fixed pin 201'. When the door 110' is opened, the module 200 slides out of the housing 100. At this point, an electrical switch (not shown) is activated. The connecting pin 911 (shown diagrammatically in FIG. 19) loops through a physical latch (not shown) of the slot to which the module 200c is connected. When the module 200c is inserted and the latch is closed, the connecting pin 911 is shorted by the module ground pin 914. In FIG. 9B, the module 200 is shown protruding from the front end 102 of the housing 100. Turning to FIG. 10A, the door 110' of the housing 100 is shown in a fully open position. As a result of the door 110' being opened, the module 200 is pulled out of the housing 100 and protrudes from the edge 102. In FIG. 10A, the carrying handle 205 of the module 200 is clearly visible. The carrying handle 205 is preferably bolted to the module 200 and can be detached. In FIG. 10B, the hinge 111' is shown rotated 90 degrees counterclockwise from the closed position. The pin 201' is outside the groove 112', allowing the module 200 to be removed from the housing 100. Moving to FIG. 11A, the module 200 is shown removed from the housing 100 and placed on the door 110'. Once the door 110' is in the fully open position, a user can manually slide the module 200 out of the housing 100 along a track (not shown) on the door 110'. An embodiment has a low-friction slide located below each module 200. 11B, a user can manually fold the carrying handle 205 upward and lift the module 200 away from the door 110'. The user can then use the carrying handle 205 to carry the module 200 to a charging station and replace it with another charged module 200. Replacing the module 200 requires performing the reverse of the removal procedure described above.

[0044]

[0072] Turning to FIG. 12 , a rear view of the enclosure 100 is shown. There are six sets of fans 120 for cooling the modules 200. Each set has three fans 120, and the sets are located between the modules 200. For example, the first set shown on the left side of FIG. 12 is located between the first and second modules 200. The second set is located between the second and third modules 200, the third set is located between the third and fourth modules 200, the fourth set is located between the fourth and fifth modules 200, and the fifth set is located between the fifth and sixth modules 200. The sixth set of fans is located between the sixth module 200 and the enclosure 100 wall. Different numbers of fans are also contemplated by the inventors to provide module cooling. Six sections of the housing 100 are hollowed out to expose the back connections of the modules 200. A 10-pin signal connector 210, a positive connector 211 and a negative connector 212 are visible on the back of each module.

[0045]

[0073] Turning to FIG. 13, a perspective view of the preferred embodiment 10 is shown showing the rear of the housing 100. This view clearly shows that the positive battery terminal 211 and the negative battery terminal 212 protrude from the rear face 103 of the housing 100. It is important to understand the purpose of having these connections 211, 212 protrude while the signal connector 210 is recessed. Before the battery module 200 is "enabled" during the insertion process, it is necessary to ensure that the high current battery terminals 211, 212 are mated. "Enabled" occurs when the 10-pin signal connector 210 completes a series connection with the bus (not shown). If the module 200 is "enabled" before being physically connected to the bus, and the bus voltage and battery voltage are different, a momentary high current will flow when the terminals 211, 212 are mated to equalize the potential. The purpose of this mechanism is to ensure that the high current connectors are mated before the battery module 200 is usable, and to disable the battery module 200 before disconnecting, for safety reasons, particularly to prevent arcing that could damage the electrical connectors.

[0046]

[0074] For these reasons, the signal connector 210 is the last connector to mate during module 200 insertion and the first connector to disengage during module 200 removal. This method requires that the pins of the 10-pin connector 210 are substantially shorter than the battery terminals 211, 212 so that during the removal process, the 10-pin connector is disconnected but the battery terminals 211, 212 remain connected. At this point in the process, the module 200 detects that it is no longer connected to the housing 100 via the 10-pin connector 210 and quickly shuts itself down before the battery terminals 211, 212 are disconnected.

[0047]

[0075] 14, a rear view of the battery module 200 is shown. The protective case 204 of the battery module 200 is preferably constructed of aluminum or another lightweight material with similar properties. The lower sheath 202' is hollowed out for a 10-pin connector 210 and battery terminals 211, 212. Each module 200 has a microcontroller and can be connected to a CAN bus using its 10-pin connector 210.

[0048]

[0076] Turning to FIG. 15, a partial front view of the battery module 200 is shown. The top sheath 203 is cut out for the display panel 225 and carrying handle 205. The display panel 225 is illuminated using LEDs and has a button 221 with a status bar 222 and a fault bar 223. The user can press the button 221 to "wake" the display from sleep mode. A coded push can be used for diagnostics. If the status bar 222 is illuminated blue, the module 200 is operating normally. If the fault bar 223 is illuminated red, there is a fault in the module 200. There are five bars 223 that illuminate green, and each bar 223 indicates the battery charge level of the module 200. The five bars 223 indicate the charge status in 20% increments from 0% to 100% charge, based on the number of illuminated LEDs. For example, one bar indicates a very low charge (approximately 20%), while five bars indicates the module 200 is fully charged (100%).

[0049] Electrical design of battery cell networks and battery modules

[0077] 16, a perspective view of the interior of module 200 is shown. Each battery cell 1710 is wire-bonded to a printed circuit board (PCB) 1722. Between the battery cell 1710 and the PCB 1722 is an upper plastic battery tray 1720a and a thermally conductive adhesive 1721 or other adhesive. The plastic battery trays 1720a, 1720b are placed directly on the top and bottom of the battery cells 1710. Thermally conductive adhesive 1721 is used between the battery trays 1720a, 1720b and the PCB 1722. The thermally conductive adhesive 1721 is also an electrical insulator.

[0050]

[0078] Turning to FIG. 17, an internal top view of the module 200 is shown. Each battery cell 1710 is wire bonded to a printed circuit board (PCB) 1722. For each battery cell 1710, three wires 1725a, 1725b, and 1725c are bonded to pads on the PCB 1722. Two wires 1725a, 1725b are negative and one wire 1725c is positive. The purpose of the two negative wires is for redundancy. A preferred embodiment contains 184 LFP battery cells. The battery cells 1710 can be divided into groups (having 23 cells) called "banks." The BSS can monitor the voltage, temperature, and state of charge for the banks, but cannot monitor individual battery cells 1710. Alternate embodiments may include variations in the arrangement or number of battery cells 1710.

[0051]

[0079] Turning to FIG. 18, a cross-sectional view of a single battery cell 1710 is shown. As previously mentioned, the battery cell 1710 and other components are surrounded by a protective enclosure 204, preferably constructed of aluminum. Directly above the battery cell 1710 is a plastic battery tray 1720a. Thermally conductive adhesive 1721a is used between the top of the battery cell 1710 and the upper battery tray 1720a. Similarly, the same thermally conductive adhesive 1721b is applied between the upper battery tray 1720a and the PCB 1722. The positive wire 1725c and two negative wires 1725a, 1725b are clearly shown wire-bonded to the top of the PCB 1722. Turning to the bottom of FIG. 18, thermally conductive adhesive 1721c is applied between the bottom of the battery cell 1710 and the lower battery tray 1720b. Additionally, thermal gap fillers 1726 are used between the bottom of the battery cells 1710 and the bottom of the protective enclosure 204. The gap fillers 1726 can transfer heat from the battery cells to the enclosure 204 so that heat can be dissipated from the module 200.

[0052]

[0080] Returning to FIG. 17 , each module 200 includes an integrated battery monitoring system (BSS). The BSS 1700 monitors cell health, including cell voltage, current, and temperature. Each module 200 is comprised of multiple battery cells 1710, which are connected in series and parallel via wire bonds and ultimately terminated in the integrated BSS 1700. The wire bonds are completed using a method similar to the Tesla ultrasonic friction welding method. The holes shown are used to wire bond the battery cells 1710 to a PCB 1722. At each hole, tiny wires 1725 a, 1725 b, and 1725 c are bonded to both the PCB 1722 and the battery cells 1710. The PCB 1722 is then used to directly transmit current throughout the interior of the battery module 200. The use of PCB 1722 prevents the entire battery module 200 from failing if one battery cell 1710 fails, since the other cells are still connected to the plates.

[0053]

[0081] A preferred embodiment of the BSS 1700 uses real-time battery cell information and compares it to a set of reference values. The BSS 1700 uses this comparison to determine anomalies in individual battery cells and multiple cells in order to diagnose problems. The diagnostic information can be transmitted externally using the communications unit. The BSS 1700 also uses this real-time data to prevent problems during battery operation by electronically disconnecting the battery from the enclosure rack 100 if a problem is detected.

[0054]

[0082] During charging, the BSS 1700 monitors the depth of discharge for each bank of 23 cells, compensates for voltage and temperature differences, and ensures that the battery bank is properly balanced. If one battery cell has slightly more or slightly less capacity than the rest, its discharge level will be different from the other batteries over several charge and discharge cycles. The BSS 1700 must balance the batteries and prevent over-discharge and over-charge, which can cause damage to the battery modules and ultimately lead to complete battery module failure, posing a safety risk.

[0055] Charging management system integration

[0083] FIG. 19 is a schematic diagram of six battery modules 200a-200f connected in parallel to an enclosure rack 100. At any given time, each battery module 200 may have a different state of charge, particularly as the modules lose charge through use in powering a forklift. The "state of charge" is defined as the charge percentage that a module 200 currently has. Each module 200 may have a different initial voltage due to differences in battery life or initial charge level. Additionally, each module 200 may have a different maximum voltage when "fully charged," taking into account differences in the age and usage of a particular module 200. For example, module 200a may have a voltage of 24.0 V when fully charged, while module 200f may have a voltage of 23.9 V when fully charged.

[0056]

[0084] A battery operating system supervisor (BOSS) module processor ("BOSS module") 901 is required to function as a battery management system for modules 200a-200f. However, under the control of the BOSS module 901, in scenarios where the voltage of one module exceeds the voltage of another, the lower-voltage battery module will draw current flow from the higher-voltage module to the lower-voltage module (limited only by the resistance of the connectors, cells, bus bars, and bond wires). A large voltage difference will cause high current flow to the battery module with the lower voltage. These situations are undesirable because current flow to the motor is reduced when current flows between battery modules rather than out of the enclosure 100. If high current is maintained for an extended period of time, or if the voltage difference is large enough to generate more current than the bond wires can handle, it can quickly deplete the battery or open the bond wires, resulting in battery failure.

[0057]

[0085] Returning to FIG. 19 , there are three bus bars in total to which modules 200 are connected. The negative terminals 212 of the modules 200 are connected to either the 0V (ground) bus bar or the 24V bus bar, depending on the group. Half of the negative terminals 212 of the modules 200 are connected to the 0V bus bar, and the other half are connected to the 24V bus bar. The positive terminals 211 of the modules 200 are connected to the 48V bus bar. As previously explained, the BOSS module 901 gives the battery modules 200 permission to decide which battery modules 200 are connected to the bus bars and which battery modules 200 are disconnected by sending signals to the modules 200. The modules 200 then use MOSFET switches to make the connection and disconnection.

[0058]

[0086] Module 200c is used here merely as an example, and it should be understood that each module 200 is wired and configured in the same manner. Communication between BOSS module 901 and modules 200 is best understood by describing the low-voltage 10-pin connection 210 (the actual connector 210 shown in FIG. 14) depicted schematically in FIG. 19. Four pins are "isolated," five pins are "non-isolated," and one spare pin is currently unused but may be deployed later. The term "pin" is also used herein to describe the wires corresponding to their respective pins on wire harnesses 904, 909. The isolated pins are grouped as part of the isolated wire harness 904. Those skilled in the art will understand that "isolation" refers to galvanic isolation. A transformer is used to isolate the isolated wire harness 904 from the main power source. If an electrical short occurs in the isolated wire harness 904, there is no risk of damage to the remaining circuits in the system. An insulated wire harness 904 is depicted as the upper dashed line that connects to module 200c. Insulated wire harness 904 is also connected to vehicle bus 920, which is a communications network depicted by multiple dashed lines. When module 200c is inserted into the "slot" in housing 100, isolated 5V pin 905 connects to module 200c and signals to BOSS module 901. There are two pins 905, 906 for communication between module 200c and BOSS module 901. There is a CAN HI pin 906 and a CAN LO pin 907. Finally, there is a ground pin 908 on insulated wire harness 904.

[0059]

[0087] The non-insulated pins are grouped as part of a non-insulated wiring harness 909. When the module 200c is inserted into the chassis 100, the identification (ID) pin 910 connects to the BOSS module 901 to assign it a CAN address in the chassis 100 (identifying the slot location of the module 200c within the chassis 100). The connection pin 911 loops through a physical latch (not shown) of the slot to which the module 200c is connected so that the BOSS module knows that the module 200c is connected. There is also a pin 912 for controlling fan power, a pin 913 for controlling fan speed, and a module ground pin 914. The battery module 200c (and all battery modules) is responsible for controlling its own fan speed and fan power. When the module 200c is inserted and the latch is closed, the connection pin 911 is shorted by the module ground pin 914. Once this happens, the BOSS module 901 can give the battery module 200c permission to connect to the bus bar.

[0060]

[0088] An example of the importance of the BOSS module 901 can be seen during continuous operation of the forklift and during module 200 replacement. The process of inserting a fully charged module 200 while the forklift is operating is known as "hot swapping." Referring to FIG. 19, module 200c is fully charged and inserted with modules 200a-200f already connected. The BOSS module 901 does not immediately grant module 200c permission to connect to the busbar. Module 200c waits until the current demands of the other modules 200 are low before connecting to the busbar. A low current demand refers to a time when the forklift does not require much current. For example, a forklift carrying a load or climbing a hill requires a lot of current. When the forklift is idle, the current demand is low, which is the appropriate time to connect module 200c. The BOSS module 901 does not control the disconnection and connection of modules 200 to the busbar. The BOSS module 901 only grants permission to modules 200 to connect and disconnect when possible. Each module 200 uses internal MOSFET switches 903a-903f to rapidly open and close the circuit connection from the module 200 to the bus bar. Once a fully charged module 200c is connected, modules 200 with lower states of charge can be disconnected. For example, if module 200f is at 60% charge and the other modules 200 are above 80%, module 200f will be disconnected and only reconnected when the other modules 200 have reduced to approximately 60% charge.

[0061]

[0089] For at least these reasons, the BOSS module 901 in the enclosure 100 is designed to monitor the charge status of each module 200 as long as it remains connected to the network, and authorizes the disconnection of any module 200 that changes beyond some threshold. This allows the forklift to continue operating without interrupting performance. While a specific 24V battery module is used in the preferred embodiment, alternative embodiments may use different voltages depending on the needs of the particular lift truck.

[0062]

[0090] Another important feature of the system 200 can be illustrated by the case when the enclosure is empty and the system is completely shut down. Unplugging modules 200 from the enclosure rack 100 automatically shuts them down. In an empty enclosure 100, inserting a module 200a does not automatically power up the BOSS module 901. For this reason, the preferred embodiment 10 has a separate continuous-hot 5V control connector 905. When a module 200a is inserted, it connects to the control connector 905, thereby powering up the BOSS module 901. This process occurs on a 5V bus, separate from the vehicle bus 920. Because the current is very low on the 5V bus, there is no risk of arcing. While the previous diagram depicts an enclosure rack 100 with one side, the preferred embodiment has two sides with a total of 12 modules 200, with six modules 200 on each side. In the preferred embodiment, six battery modules 200 are parallel-connected in each enclosure 100 to obtain higher current capacity at a constant voltage. Alternate embodiments may employ any number of battery modules.

[0063] Alternative Embodiments

[0091] The following items describe alternative embodiments of the disclosed system.

[0064] Lithium-ion battery module system design

[0092] FIG. 21 provides an elevation view of an alternative embodiment rechargeable battery assembly 220 separated from the forklift 130. The rechargeable battery assembly 220 has eight removable and replaceable battery modules 330a-330h that are operably inserted into one of eight identical module bays 301a-301h defined within an outer housing 300. The housing 300 forms the exterior of the larger battery assembly 220, whose overall height (labeled "H" in FIG. 21), depth (also labeled "D" in FIG. 3), and width (i.e., the dimension perpendicular to the sheet of FIG. 3; width is not labeled in FIG. 21) are approximately the same as the height, width, and depth of a lead-acid battery 160 (shown in FIG. 2) that is sized appropriately for intended use in the forklift 130.

[0065]

[0093] An alternative embodiment is in the form of a single enclosure rack 300 with the capacity to receive and manage eight removable battery modules 330, each of which is interchangeable with the others. FIG. 21 shows only four modules because the alternative embodiment has two symmetrical arrangements with four modules aligned back-to-back. As a result, the handles are exposed through openings in the removable panels on both sides of the forklift 136. This also simplifies the enclosure rack's connection points to just one location. The enclosure rack 300 serves multiple purposes and benefits. In addition to housing the battery modules 330 within the forklift 100, the rack can be removed and used as a charging station (typically a floor-mounted charging station). The enclosure rack 300 of the alternative embodiment is constructed of metal. In a particularly preferred embodiment, the enclosure rack 300 is constructed of steel, which provides durability. In addition to providing durability, constructing the housing rack 300 from steel adds weight, which can help prevent the housing rack 300 from tipping over when one or more battery modules 330 are removed (particularly when the housing rack 300 is used as a charging station). Other materials are contemplated, including, but not limited to, composites and polymers.

[0066]

[0094] In addition to having forklift battery-sized dimensions as previously described, the bottom surface 304 of the enclosure rack 300 is preferably weight-adjusted by attaching a heavy material thereto (preferably in the form of steel plates placed thereon, but within the enclosure of the enclosure 300). The additional weight of these steel plates increases the overall weight of the assembly 220, resulting in a weight that exceeds the minimum battery weight specified by the forklift 130 manufacturer, while still allowing for the lightweight characteristics of the removable modules 330 (each weighing less than 51 pounds). Those skilled in the art will recognize that this counterweight could be made of a heavy material, such as high-density steel, and constructed from multiple plates or sections to allow the user to manipulate the center of gravity 161 to maximize the safe lifting capacity of the forklift. Alternative embodiments could include, but are not limited to, different locations for the adjustable counterweight (e.g., on top of the enclosure rack) and multiple variations in the materials of the enclosure rack and counterweight. The chassis rack 300 can be designed so that the rack itself can be replaced with a chassis rack 220 of a different material to adjust the counterweight.

[0067]

[0095] It is contemplated that the minimum battery weight requirement may be met with an enclosure rack 300 and counterweight having fewer than a full population of battery modules 330. This is to allow a user to still safely operate the forklift 100 if there are not enough fully charged battery modules. Alternative embodiments may meet the weight requirement with six to seven modules. Other alternative embodiments ideally meet the minimum weight requirement with less than a full population of approximately one to three batteries 330.

[0068]

[0096] Combined with the modest weight of the enclosure rack 300, the alternative embodiment weighs substantially less than a conventional lead-acid battery. Even in situations where the enclosure rack 300 has imperfectly aligned battery modules 330, the modules still weigh less than 51 pounds. Each battery module 330 or "pack" is equipped with a handle 335 on the rear of the module. The handle 335 is designed to ensure easy grasping and safe movement of the module. The design of the handle and the functional methods for removing and installing the modules 330 are discussed in more detail in subsequent sections.

[0069]

[0097] Alternate embodiments include other adaptations to enable or ensure safe removal of both the battery modules and the enclosure rack 300 from the forklift 130. Preferably, a module release button 333 is located on the rear of each battery module 330, ensuring safe detachment of the module 330 from the enclosure rack 300; safe detachment is considered from a mechanical standpoint. Electrical detachment occurs with a linking pin configuration. This button is described in more detail below in the section "Enclosure Rack and Battery Module Interface Design." The front of the battery module also has an indicator that shows whether the battery is actively engaged or switched off. Those skilled in the art will recognize that this indicator can take on a variety of alternative embodiments, including, but not limited to, a small LED indicator, a light that illuminates as part of the button 333, or an LCD display panel on the front of the battery pack that also displays other indicators of battery health. In this alternate embodiment, the LCD display panel displays indicators used to monitor battery health (including, but not limited to, voltage, temperature, and remaining battery life).

[0070]

[0098] FIG. 21 includes another important safety feature. Located within bosses 225 on the top of the enclosure rack assembly 300 are eyehooks 226. An alternative embodiment of the enclosure rack 300 includes eyehooks 226 on both ends of the enclosure rack for easy removal of the rack from or installation of the rack into the forklift battery compartment. Those skilled in the art will recognize that the boss 225 and eyehook 226 configuration mimics the existing eyehooks 125 and safety removal mechanisms currently used in conventional lead-acid battery 160 designs to ensure full backward compatibility. This configuration may differ from the configuration depicted in FIG. 21. Alternative embodiments may utilize different methods for removing the enclosure rack 300 from the forklift 130, provided that removal is accomplished in a safe and convenient manner.

[0071]

[0099] FIG. 22 shows a rear view of one half of the housing rack 300, revealing the battery pack connection points. The location of this display surface is shown as section 4-4 in FIG. 23. Another eyehook 226 is located at the top of the rear of the housing rack 300. Located on the rear of the battery pack 330 is a 6-pin male connector 400, a positive battery terminal 401, and a negative battery terminal 402, which are the only wire connection points for engaging and disengaging the module. Within each module 330 are multiple lithium-ion battery cells. Those skilled in the art will recognize that other connectors with various numbers of pins can be implemented. The outer casing of the battery module 330 is constructed from a rigid, lightweight metal. Other materials are contemplated, including, but not limited to, alloys, composites, and polymers.

[0072]

[0100] FIG. 23 is an isometric view of an alternative embodiment of the enclosure rack 300. This alternative embodiment has eight battery modules 330 (four shown here) arranged back-to-back in two stacks of four. When installed in the enclosure 300, each module 330 sits atop a low-friction slide 310, which allows the module 330 to slide in and out of a corresponding bay 307 within the enclosure 300 for assembly. Features previously described with respect to the modules are also included in this view. The front of each module has a handle 335, and the rear has a removal button 333. The rack button releases the unit for withdrawal from the rack. The pack relies on a pin connection (first connect, last disconnect) to power on and off the high-current terminals. A latch holds the batteries in place to prevent loose contact. A six-pin connector 400, a positive connector 401, and a negative connector 402 are visible on the back of each module. Additionally, eyehooks 226 and bosses 225 are found on the front and back of the enclosure rack 300 .

[0073] Battery Module Design

[0101] 24A and 24B are isometric views of a battery module 330, showing the individual battery modules and frictionless slide 310. FIG. 24A depicts the front of an alternative embodiment of the module 330, in which both the release button 333 and the handle 335 are visible. As previously mentioned, the handle 335 is used to safely carry and remove the module 330. As is evident from FIG. 24A, the alternative embodiment uses a handle bolted to the underside of the front of the module 330. Those skilled in the art will recognize that the handle will be positioned to ensure easy lifting and easy grasping, and that its relative dimensions and location may differ from those shown in FIG. 24A. The handle 335 is designed to carry the weight of the entire module.

[0074]

[0102] The handles 335 allow a user to move the modules 330 within the enclosure rack 300 in a manner similar to a drawer and are constructed from a rigid, lightweight metal. Other materials are contemplated, including, but not limited to, alloys, composites, and polymers. Alternate embodiments contemplate that individual modules 330 may include handles on the back or sides. Each of these handles is constructed in a manner that allows for easy grasping of the battery module 330 and safe movement of the module. One skilled in the art will recognize that handles added to modules in alternate embodiments may have battery connection points or hinges that lie flush with a surface so as not to interfere with movement in and out of the battery rack 300.

[0075]

[0103] FIG. 24B depicts the back of the battery module. The 6-pin connector 400 is wired directly to the BSS, which is used to monitor the battery health. Finally, the positive terminal 401 and negative terminal 402 are connected to the same battery cells. The positive terminal 401 and negative terminal 402 are connected to the housing rack 300 through the use of a quick-release connection. The requirements for this quick-release connection are that it can maintain performance through a high number of cycles, it can blindly connect the battery module 330 to the housing rack 300, and it can safely transfer current from the module 330 to the housing rack 300 through multiple contact points. An alternative embodiment utilizes a spring-biased connection to allow each battery terminal 401, 402 to slide into a corresponding socket when the battery module 330 is connected. Other alternative embodiments can utilize similar quick-release connections that allow for blind sliding connection and disconnection.

[0076]

[0104] Due to the nature of the use of multiple battery modules 330 in a larger enclosure rack 300, the removal and installation of modules from and into the rack is an important aspect of this design. Alternative embodiments have low friction slides 310 located below each battery pack. Alternative embodiments may use other methods to achieve this sliding motion, such as the use of rollers or ball bearings to facilitate removal and installation, to position modules 330 into the enclosure rack 300.

[0077]

[0105] In such an alternative embodiment, the module 330 slides on cylindrical rollers with roller bearings and is guided by tracks on either side of the module that are co-located with the frictionless slide 310. In this embodiment, the rollers and roller bearings are constructed from a lightweight metal. Alternative embodiments can employ various types of roller bearings and rollers constructed from different materials other than metal. It is contemplated that all design embodiments will include some method for preventing the module from moving uncontrollably out of the assembly.

[0078]

[0106] An alternative embodiment of battery module removal is contemplated to accomplish two things: provide a mechanism to prevent uncontrolled battery removal and avoid adding an excessive number of additional moving parts to the battery module design. In FIG. 24A , the alternative embodiment includes two catches 603, 604 located on either side of the module connected to the housing rack 300. There are also two tabs on either side of modules 605, 606. The catches 603, 604 are intended to capture the battery tabs 603, 604 along the rear sides of the module to prevent the batteries from accidentally sliding out. The movement of the battery module 330 during removal in the alternative embodiment is shown as dashed section 607 in FIG. 24A . The module 330 is removed from the housing rack assembly 300 by grasping the handle 335 on the front of the module and sliding the case forward in the direction of arrow 608. The module slides along low-friction slides 310 until battery tabs 605, 606 contact stops 603, 604 on the housing rack assembly 300. The module 330 must then be lifted over stops 603, 604 for full removal in the direction of arrow 609. In this alternative embodiment, the installation operation requires the exact opposite order of steps as removal.

[0079]

[0107] Other alternative embodiments of this design may include, but are not limited to, stops to allow the battery module 330 to pivot downward 90° so that the battery can be lifted off the rotation rod by a handle on the back of the module. Additionally, the rotation rod is preferably connected to rotation dampeners located on either side of the housing rack 300. These rotation dampeners slow the rotation of the battery module 330 to its vertical lift orientation during removal, thereby reducing the chance of damaging the battery module 330 or the housing rack 300. Alternative contemplated embodiments may include detents or latches on the exterior of the battery, implemented to prevent failure before the end of the battery's life.

[0080] Electrical design of battery cell networks and battery modules

[0108] FIGS. 25A and 25B show isometric views of the top and bottom of a battery module 330, respectively. Each battery pack 330 is composed of multiple battery cells, which are connected in series and parallel via wire bonds and ultimately terminated into an integrated battery support 700. The wire bonds are completed using a method similar to the Tesla ultrasonic friction welding process. While wire bonds are widely used in other contexts, such as integrated circuits and discrete electronics, the battery industry has incorporated wire bonds that allow for ever larger gauge wires. Both figures show multiple battery plates 701-709. The holes shown in each plate are used to wire bond the battery cells to the plate. At each hole, a very small wire is bonded to both the plate and the battery cell. The plates are then used to directly transmit current throughout the interior of the battery module 330. The use of plates prevents the entire battery module 330 from failing if one battery cell malfunctions, since the other cells are still connected to the plate.

[0081]

[0109] The multiple cells are connected by arranging electrode plates 701 to 709 as shown in Figures 25A and 25B. Four electrode plates (702, 704, 706, 708) are arranged on the upper surface inside the battery module, and five electrode plates (701, 703, 705, 707, 709) are arranged on the lower surface inside the battery module.

[0082]

[0110] Each plate alternates between a positive and a negative battery cell configuration. For plates 702-708, this is approximately half the geometric area of ​​the space. In an alternative embodiment, each of these interior plates contacts 50 battery cells, half of which are negative contacts and half of which are positive contacts, with the most negative and most positive plates each contacting 25 cells. Plates 701 and 709 only contact the positive end (701) or the negative end (709) of the battery cells, and therefore only contact 25 cells. These plates are also directly connected to the battery terminals or BSS. Plate 701 is connected to the BSS, which is then connected to the positive terminal 401. Plate 709 is connected to the negative terminal 402. An alternative embodiment contains 200 LFP battery cells. Alternate embodiments may include variations in the arrangement or number of battery cells, which also implies that the plates of alternate embodiments may have a different number, arrangement, or geometry than alternate embodiments.

[0083]

[0111] As the current flows through the battery cells, it alternates between the top and bottom of the module 330 as it travels around the module 330. The current flows from the positive terminal 401 to plate 701, which is located at the bottom of the battery module (FIG. 25B). Plate 701 is positively charged and contacts only the positive ends of the 25 battery cells above it. The negative ends of these battery cells contact the negative portion of plate 702, which is located at the top of the battery module (FIG. 25A). The negative portion of plate 702 is indicated by dashed section 702a. The other half of plate 702 (702b) contacts the positive ends of the 25 cells below it. In 702a, the plate has contacts with the ends of the 25 negative battery cells, and in 702b, the plate has contacts with the ends of the 25 positive cells. The negative end of the battery cell of plate 703 is then the same cell that has a positive connection to portion 702b of plate 702. These cells have a negative connection to plate 703. The other half of plate 703 is located in region 704a. This region contains the positive contact point with the battery cell. Region 704b of plate 704 continues the pattern and has a negative connection to plate 705. Here, the contact point of plate 705 is negative. The other half of plate 705 is positively connected, and the cell also has a negative connection in region 706a of plate 706. Region 706b is positively connected at the top and negatively connected to plate 707 at the bottom. The other half of the plate is positively connected and has a negative connection to 708a. Current passes through the positive connection of 708b. By the time the current reaches negative plate 709, a negative voltage flows from the negative terminal 402.

[0084]

[0112] The integrated BSS 700 monitors the health of the modules 330, including cell voltage, current, and temperature. Regarding monitoring, some embodiments can incorporate a display with multiple LED lights for the purpose of monitoring the status of the battery modules 330. For example, the display can have seven LEDs, five of which indicate charge status in 20% increments from 0% to 100% based on the number of illuminated LEDs. The other two LEDs can indicate status and trouble codes based on illumination color and / or by LED flashing sequences or patterns, with different flashing sequences or patterns associated with specific trouble codes. Additionally, each display can incorporate a push button that can be used to query the status of a particular battery module 330 and to troubleshoot the battery module 330 by the number of button presses or the duration of the button press. Each figure (FIGS. 25A-25B) shows the BSS 700 and flexible cables 710 wired from the 6-pin connector 400 to each section of the battery cells. In an alternative embodiment, a flexible cable 710 is used to wire all diagnostic equipment to measure temperature, current, and voltage. Additionally, each module 330 contains field-effect transistors (FETs) 711 placed in series with the battery cells to ensure proper power handling. These switches are an aspect of the alternative embodiment that allows for the removal of the module from the enclosure rack 300, as well as function as an active, resettable fuse element. The number of FETs 711 is based on the power capacity of the cells; upon removal of the module 330 from the enclosure rack 300, the FETs 711 prevent power from being applied to the terminals. One alternative embodiment has 20 FETs 711, although other alternative embodiments of this design with different power capacities would, of course, have different numbers of FETs or their equivalent.

[0085]

[0113] An alternative embodiment of the BSS 700 uses real-time battery cell information and compares it to a set of reference values. The BSS 700 uses this comparison to determine anomalies in individual battery cells and multiple cells to diagnose problems. The diagnostic information can be transmitted externally using the communications unit. The BSS 700 also uses this real-time data to prevent problems during battery operation by electronically disconnecting the battery from the enclosure rack 300 if a problem is detected.

[0086]

[0114] During charging, the BSS 700 monitors the depth of discharge for each cell, compensates for voltage temperature differences, and ensures that the battery cells are properly balanced. If one battery cell has slightly more or slightly less capacity than the rest of the batteries, its discharge level will be different from the other batteries over several charge and discharge cycles. The BSS 700 must balance the batteries and prevent over-discharge, over-charge, and deep-discharge. Over-discharge, over-charge, and deep-discharge can cause damage to the battery module and ultimately cause complete battery module failure, posing a safety risk.

[0087]

[0115] In an alternative embodiment, a Controller Area Network (CAN) communication protocol is used as the primary BSS. CAN buses have error detection and fault tolerance, but some significant material costs and communication overhead. Various communication systems can be implemented for information transmission. Other alternative embodiments can use industrial transmission interfaces, such as a serial peripheral interface (SPI), DC-BUS, or local interconnect network (LIN bus). In an alternative embodiment, the CAN interfaces with each BSS, effectively monitoring and controlling the performance of the entire battery enclosure rack. This prevents inter-battery performance issues and utilizes each module as efficiently as possible. In this way, the CAN allows the enclosure rack to interact with the VCU as a single unit, rather than allowing each battery module to interact with the VCU individually. Furthermore, a separate CAN scheme can be implemented, allowing communication with the “top” battery module of a stack of battery modules, which may be at a voltage potential that is somewhat higher than the battery modules lower in the stack.

[0088] Housing rack and battery module interface design

[0116] FIG. 26 is a top-down schematic view of the battery module, showing the mechanism for removal and installation in the rack. The battery module 330 is removed by pressing a button 333 on the exterior handle. The button 333 ensures that the module 330 stays in place during forklift operation. Pressing the button 333 releases tension from the spring-loaded male connector 800, pushing the male connector 800 out of the female connector 801 and disconnecting the battery module terminals 401, 402 from the housing rack terminals 802, 803. The male connector 800 and female connector 801 engage first and disengage last. In FIG. 26, 800-803, 401, 402 are symbolic representations for illustrative purposes. Alternative embodiments of this portion of the system are different sizes and more complex, but accomplish the same task.

[0089]

[0117] To install a removable battery module 330 into a slotted bay 307 of the rack 300, a user first manually places the rear face of the battery module 330 into the opening of the corresponding bay 307 and then manually slides it backward into the bay. Once the module 330 is slid far enough that the rear face of the module 330 contacts the spring-loaded male connector 800, the connector 800 begins to compress. After the connector 800 fully compresses, the module 330 is locked in place. The connector 800 is intended to be constrained from movement along the insertion axis. The system is spring-loaded to achieve pressure contact of the battery module terminals 401, 402 to the chassis rack terminals 802, 803. The male connector 800 presses a rear switch located in the female connector 801 that serves as an on / off mechanism for the system.

[0090]

[0118] Additionally, there is a need to safely disconnect the battery module from the enclosure rack before fully removing it to prevent arcing. Arcing can result in overcurrent and, without proper precautions, can destroy the battery. In particular, if the battery module 330 is enabled before it is physically connected, and in particular if the battery module 330 is enabled (i.e., electrically connected to the male connector 800) before it is physically connected to the male connector 800 and has a different voltage, a momentary high current will flow to equalize the potentials when the connectors 800 and 801 physically mate. The goal is to ensure that the high-current connector is engaged before the battery module 330 is enabled and that the battery module 330 is disabled before it is disconnected. This can be achieved through several methods. One such method is to use the button 333 next to the handle to send a signal to the processor to stop powering the terminals. An alternative method is to use a pressure-sensitive switch on the back of the battery module that turns on the battery only when the battery is fully engaged with the connector. The relative dimensions of the switch and power connector are such that the switch protrudes far enough from the back of the battery to disengage before the battery module is completely disconnected.

[0091]

[0119] Another alternative method is by electronic signaling. As previously mentioned, the battery module is connected to the housing rack by both the pin connector and the battery terminals. The electronic signaling method requires that the pin connector be substantially shorter than the battery terminals so that during the removal process, the pin connector is disconnected but the battery terminals remain connected. At this point, the battery module detects that it is no longer connected to the housing rack via the pin connector and immediately shuts itself down before the battery terminals are disconnected. Those skilled in the art will understand that alternative embodiments can employ mechanisms other than those employed in FIG. 26 or those described as alternatives. The purpose of the mechanism is for safety, specifically to prevent arcing.

[0092]

[0120] An additional feature of the alternative embodiment is reflected in the battery module 330 being compatible with prior art chargers used to recharge conventional battery assemblies 160 (shown in FIG. 2) designed for use in forklifts 130. Due in part to Applicant's design of the lithium iron phosphate cell module 330, which when assembled into a module according to an embodiment can be safely charged by a conventional charger, the features and structure of the module 330 are such that the lithium-ion batteries can be recharged by chargers that recharge conventional forklift batteries 160 currently in use and already installed in warehouses.

[0093] Charging management system integration

[0121] FIG. 26 is a schematic diagram of an alternative embodiment in which eight battery modules 330a-330h are connected in parallel to an enclosure rack 300 with its own BSS 901. At any particular time, each battery module 330 may have a different voltage, as suggested by the voltage numbers shown in FIG. 26, particularly as the modules lose charge through use in powering the forklift 130. Each module may have a different initial voltage due to differences in battery life or initial charge level. In the example of FIG. 26, two modules have a fully charged voltage of 36.0V, and the other modules have a lower voltage, as shown.

[0094]

[0122] However, with BSS 901 control, in scenarios where the voltage of one module exceeds the voltage of the other, the lower voltage battery module will draw current flow from the higher voltage module to the lower voltage module (limited only by the resistance of the connectors, cells, bus bars, and bond wires). A large voltage difference will cause high current flow to the battery module with the lower voltage. These situations are undesirable because current flow to the motor is reduced when current flows between battery modules rather than out of the enclosure rack. If high current is maintained for an extended period of time, or if the voltage difference is large enough to create more current than the bond wires can handle, it can also lead to battery failure by quickly depleting the battery or opening the bond wires.

[0095]

[0123] For these reasons, the primary BSS 901 in the enclosure rack 300 is designed to monitor the voltage of each module as long as it is connected to the network, and will disconnect any module that varies above a 0.10V threshold. This allows the forklift to continue operating without interrupting performance. A specific 36V battery module is used as an example, as alternative embodiments can use various voltages depending on the needs of a particular lift truck.

[0096]

[0124] Other alternative embodiments of the battery monitoring system architecture are contemplated within the scope of the present invention. In one embodiment, each battery module contains a PC board with a digital isolator and a multi-cell battery stack monitor. Each module has an independent interface connection to a controller board with a microcontroller, CAN interface, and galvanic isolation transformer. The microcontroller provides a gateway to the forklift's main CAN bus and can coordinate the modules.

[0097]

[0125] In another alternative embodiment, each multi-cell battery stack monitor (MBSM) resides on a PC board within each battery module. The BSS also contains a CAN transceiver and galvanic isolation transformer. Each module communicates through the MBSM's non-isolated SPI-compatible serial interface. This configuration requires three- or four-conductor cables to be connected between battery modules. A single microcontroller controls all battery monitors through the bottom monitor integrated circuit. This microcontroller also serves as a gateway to the forklift's main CAN bus.

[0098]

[0126] Another contemplated embodiment does not have monitor and control circuitry within any of the battery modules. One PC board has three MBSM integrated circuits (for the three modules), each connected to a battery module. The MBSM devices can communicate through a non-isolated SPI-compatible serial interface. One microcontroller controls all battery monitors through the SPI-compatible serial interface and is the gateway to the forklift's main CAN bus. As with the previous disclosed embodiment, a CAN transceiver and galvanic isolation transformer complete the BSS.

[0099] Further alternative forms

[0127] While the present invention has been described with reference to the foregoing disclosed embodiments, this description is provided merely as illustrative and is not intended to be limiting. For example, despite such reference to a Class I forklift, it should be understood that certain aspects of the present invention may have broader applicability in other types of battery-powered industrial trucks. Indeed, while the foregoing description refers to many components and other embodiments presently contemplated, those skilled in the art will recognize many possible alternatives not expressly mentioned or even recommended herein. While the foregoing description should enable one skilled in the art to make and use what is currently considered to be the best mode of the invention, those skilled in the art will also understand and appreciate the existence of many variations, combinations, and equivalents of various aspects of the specific embodiments, methods, and examples referred to herein.

[0100]

[0128] Accordingly, the drawings and detailed description herein are to be regarded as illustrative rather than exhaustive. They are not intended to limit the invention to the particular forms and examples disclosed. To the contrary, the present invention embraces many further modifications, variations, rearrangements, substitutions, alterations, design choices, and embodiments that will be apparent to those skilled in the art without departing from the spirit and scope of the present invention.

[0101]

[0129] Accordingly, it should be understood that in all respects the drawings and detailed description herein are to be regarded as illustrative rather than restrictive, and that the invention is not intended to be limited to the particular forms and examples disclosed. In all cases, all substantially equivalent systems, articles and methods are to be regarded as within the scope of the present invention, and unless expressly indicated otherwise, all structural or functional equivalents are anticipated to remain within the spirit and scope of the presently disclosed systems and methods.

Claims

1. 1. A rechargeable battery assembly configured to power a vehicle, comprising: an assembly housing sized to operably fit within a battery assembly compartment of the vehicle; A plurality of battery modules disposed within the assembly housing, each battery module comprising: A module casing; a positive battery terminal and a negative battery terminal; a printed circuit board (PCB) disposed within the module casing and electrically coupled to the positive battery terminal and the negative battery terminal; a plurality of battery cells disposed within the module casing adjacent a first side of the PCB and electrically coupled to the PCB to provide a coupling potential between the positive battery terminal and the negative battery terminal; Each of the plurality of battery cells is a first wire bonded to a second side of the PCB opposite the first side of the PCB and to a positive terminal of the battery cell, the first wire passing through an opening in the PCB that allows access to the first side of the PCB from the second side of the PCB; a second wire bonded to the second side of the PCB and to a negative terminal of the battery cell, the second wire passing through the same opening in the PCB as the first wire; electrically coupled to the PCB by a plurality of battery cells, each of the plurality of battery cells being coupled to the PCB to form a plurality of battery cell banks, each of the plurality of battery cell banks including a group of the plurality of battery cells coupled to each other via wire bonds to the PCB; a battery monitoring system (BSS), each of the plurality of battery cell banks terminating in the BSS, the BSS configured to monitor a characteristic of each of the plurality of battery cell banks; A rechargeable battery assembly comprising:

2. For each of the plurality of battery modules, The BSS includes: monitoring a depth of charge of each of the plurality of battery cell banks; 13. The rechargeable battery assembly of claim 1, configured to manage charging and discharging of each of the plurality of battery cell banks based on a depth of charge of each of the plurality of battery cell banks.

3. For each of the plurality of battery modules, and managing the charging and discharging of each of the plurality of battery cell banks, The BSS includes: determining that a depth of charge of one of the plurality of battery cell banks is less than a depth of charge of the remainder of the plurality of battery cell banks; regulating discharge from the plurality of battery cell banks to ensure that one of the plurality of battery cell banks is properly balanced with the remainder of the plurality of battery cell banks; 3. The rechargeable battery assembly of claim 2, wherein the rechargeable battery assembly is configured as follows:

4. For each of the plurality of battery cells in each of the plurality of battery modules, Each of the first wire and the second wire is Passing a desired current between the battery cell and the PCB; and acting as a fuse by opening in response to a current greater than the desired current being conducted between the battery cell and the PCB.

2. The rechargeable battery assembly of claim 1, wherein the rechargeable battery assembly is configured as follows:

5. For each of the plurality of battery modules, 2. The rechargeable battery assembly of claim 1, wherein each of the plurality of battery cells is further electrically coupled to the PCB by a third wire bonded to the second side of the PCB and to a negative terminal of the battery cell, the third wire passing through an opening in the PCB.

6. For each of the plurality of battery modules, 2. The rechargeable battery assembly of claim 1, wherein the PCB comprises a plurality of openings, each of the plurality of openings being associated with at least one of the plurality of battery cells.

7. For each of the plurality of battery cells in each of the plurality of battery modules, a positive terminal of the battery cell disposed at a first end of the battery cell adjacent the first side of the PCB; 10. The rechargeable battery assembly of claim 1, wherein the negative terminal of the battery cell is disposed along an outer edge of the first side of the battery cell.

8. For each of the plurality of battery cells in each of the plurality of battery modules, 8. The rechargeable battery assembly of claim 7, wherein the second ends of the battery cells are disposed in connection with a thermally conductive material that is connected to the module casing.

9. 10. The rechargeable battery assembly of claim 1, wherein each of the plurality of battery cells of each of the plurality of battery modules is a lithium ion battery cell.

10. 10. The rechargeable battery assembly of claim 9, wherein each of the plurality of battery cells of each of the plurality of battery modules is a lithium iron phosphate battery cell.

11. 10. The rechargeable battery assembly of claim 1, wherein the vehicle is a forklift truck.

12. 1. A rechargeable battery assembly configured to power a vehicle, comprising: an assembly housing sized to operably fit within a battery assembly compartment of the vehicle; A plurality of battery modules disposed within the assembly housing, each battery module comprising: A module casing; a positive battery terminal and a negative battery terminal; a printed circuit board (PCB) disposed within the module casing and electrically coupled to the positive battery terminal and the negative battery terminal; a plurality of battery cells electrically coupled to the PCB to provide a coupling potential between the positive battery terminal and the negative battery terminal; Each of the plurality of battery cells is a first wire bonded to the PCB and to a positive terminal of the battery cell; a second wire bonded to the PCB and to the negative terminal of the battery cell; electrically coupled to the PCB by the first wire and the second wire pass through the same opening in the PCB; a plurality of battery cells, each of the plurality of battery cells being coupled to the PCB to form a plurality of battery cell banks, each of the plurality of battery cell banks including a group of the plurality of battery cells coupled to each other via wire bonds to the PCB; A plurality of battery modules, A rechargeable battery assembly comprising:

13. each of the plurality of battery modules includes a battery monitoring system (BSS), each of the plurality of battery cell banks terminates in the BSS; The BSS includes: monitoring a depth of charge of each of the plurality of battery cell banks; 13. The rechargeable battery assembly of claim 12, configured to manage charging and discharging of each of the plurality of battery cell banks based on a depth of charge of each of the plurality of battery cell banks.

14. For each of the plurality of battery modules, and managing the charging and discharging of each of the plurality of battery cell banks, The BSS includes: determining that a depth of charge of one of the plurality of battery cell banks is less than a depth of charge of the remainder of the plurality of battery cell banks; regulating discharge from the plurality of battery cell banks to ensure that one of the plurality of battery cell banks is properly balanced with the remainder of the plurality of battery cell banks; 14. The rechargeable battery assembly of claim 13, wherein the rechargeable battery assembly is configured as follows:

15. For each of the plurality of battery modules, the plurality of battery cells are disposed within the module casing adjacent a first side of the PCB; For each of the plurality of battery cells, the first wire is bonded to a second side of the PCB opposite the first side of the PCB and to a positive terminal of the battery cell, and an opening in the PCB allows access to the first side of the PCB from the second side of the PCB; 13. The rechargeable battery assembly of claim 12, wherein the second wire is bonded to the second side of the PCB and to a negative terminal of the battery cell.

16. For each of the plurality of battery modules, 16. The rechargeable battery assembly of claim 15, wherein the PCB comprises a plurality of openings, each of the plurality of openings being associated with at least one of the plurality of battery cells.

17. For each of the plurality of battery cells in each of the plurality of battery modules, Each of the first wire and the second wire is Passing a desired current between the battery cell and the PCB; and acting as a fuse by opening in response to a current greater than the desired current being conducted between the battery cell and the PCB.

13. The rechargeable battery assembly of claim 12, configured as follows:

18. For each of the plurality of battery modules, 16. The rechargeable battery assembly of claim 15, wherein each of the plurality of battery cells is further electrically coupled to the PCB by a third wire bonded to the second side of the PCB and to a negative terminal of the battery cell, the third wire passing through an opening in the PCB.

19. For each of the plurality of battery cells in each of the plurality of battery modules, a positive terminal of the battery cell disposed at a first end of the battery cell adjacent the PCB; 13. The rechargeable battery assembly of claim 12, wherein the negative terminal of the battery cell is disposed along an outer edge of the first side of the battery cell.

20. For each of the plurality of battery cells in each of the plurality of battery modules, 20. The rechargeable battery assembly of claim 19, wherein the second ends of the battery cells are disposed in connection with a thermally conductive material that is connected to the module casing.

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