Modular lithium-ion battery system for fork lift

Abstract

To provide a modular rechargeable battery system allowing replacement work of batteries in a fork lift to be performed safely.SOLUTION: Many embodiments involve rechargeable battery assemblies that are forklift-battery-sized but that comprise multiple removable battery modules 200. The battery modules are individually rechargeable and are interchangeable with each other. A housing 100 contains six battery modules installed vertically on the front side of the assembly, and their electrical and data connections occur within the housing on the rear side. Assemblies are two sided so that a system has two racks with six modules per rack. Each battery module has an integrated battery supervisor system (BSS). A battery operating system supervisor (BOSS) module processor serves as a battery management system for the all the battery modules.SELECTED DRAWING: Figure 1

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 hereby incorporated by reference as if set forth in their entirety herein.

[0002] 2. Background of the Invention 1. Field of the invention

[0002] The present invention relates to battery powered industrial trucks and their rechargeable batteries, and to 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

[0003] Before reviewing the particular field of the present invention, it may be useful to consider some background information about rechargeable lithium-ion batteries in general. Rechargeable lithium-ion batteries were developed in the 1970s, and even at that time many of their benefits and potential industrial applications were well understood. Initially, they were slow to find commercial use, but 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. In industrial use, lithium metal oxides have been the most successful, with lithium cobalt oxide (LCO or LiCoO2) being the most popular, but their use has been fraught with drawbacks, particularly with regard to thermal runaway and associated safety concerns. As development has progressed, substantial improvements have been realized by doping the lithium positive electrode forming materials with additional metals (such as nickel, manganese, and aluminum). Innovations have also involved the use of core-shell particle cathodes, improved anodes and solid lithium polymer electrolytes, while other advances 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). Other 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 may also be considered for specific needs. For example, lithium metal phosphates have also long been available for improved cycle times, shelf life, and safety in theory, but other performance tradeoffs have made them less popular among manufacturers than the LCO type. One specific type of lithium metal phosphate, the lithium iron phosphate (LFP or LiFePO4) battery, has long been known as an available type of rechargeable lithium-ion battery, but has various advantages and disadvantages compared to NCA, NMC, and other LCO batteries, which have generally been weighed against the use of LFP.

[0005]

[0005] As a particularly successful example of the implementation of lithium-ion batteries in other fields, Tesla, Inc. popularized the use of NCA batteries for its Model S electric vehicle. A batteries work very well due to their high energy density, but they have relatively low thermal stability and tend to have a thermal runaway temperature of about 150°C. Tesla's battery manufacturing method is It helps balance the benefits and risks by safely interconnecting hundreds of smaller battery cells in a much larger assembly to achieve the required energy density while minimizing the risk of discharge and overheating. Within the larger assembly, the hundreds of smaller battery cells are connected in groups, each group containing a parallel arrangement of many 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 for the electric vehicle. This method permanently connects each terminal of each cell to the entire assembly. However, rather than using the traditional methods of soldering, resistance spot welding, or laser welding, Tesla uses ultrasonic vibration welding, which uses wire bonds to create the desired energy density. The 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 that is then electrically coupled to the 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 to have better thermal stability. Thermal runaway in LFP batteries typically does not occur until about 270°C, thereby improving safety and reducing the chance of catastrophic complete failure. LFP batteries are also more stable under short circuit or overcharge conditions and do not decompose as easily at high temperatures. As other demonstrable advantages, LFP batteries also tend to have greater power density (i.e., can deliver higher power levels per unit volume) and significantly increased cycle life compared to lead-acid batteries. While a typical lead-acid battery has an average life of 300 cycles with a 20% degradation of stored charge, an LFP battery can last in excess of 2000 cycles with the same 20% degradation of stored charge.

[0007]

[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 1000 pounds, and therefore many forklifts have been designed to use the weight of the lead-acid batteries to maintain stability. However, their large weight also presents many challenges, especially in the context of removing, replacing, and otherwise handling the lead-acid batteries. Since workers cannot safely lift that much, special hoists and battery replacement equipment are required, which in turn requires additional costs and floor space. Of course, this also creates a risk of back injuries and the like.

[0008]

[0008] Besides the weight-related risks, due to the corrosive nature of sulfuric acid, lead-acid batteries also present a risk of damage to the eyes, lungs, skin and clothing of workers who handle them. In addition, hydrogen gas is typically released during battery recharging, which can combine explosively with oxygen and promote corrosion of surrounding components. As a result, lead-acid batteries require special safety protocols and special care to ensure proper ventilation against hydrogen and sulfur odors around forklifts and their recharging stations.

[0009]

[0009] Moreover, forklift lead acid batteries are expensive in terms of time, space and inventory. Forklift lead acid batteries typically only last about six hours of continuous use before needing to be recharged for eight to nine hours. 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 to be dedicated to charging and maintenance, and each forklift typically requires two spare batteries for a facility that operates 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, but the resulting attempts have been, at best, ineffective, and many of the challenges of the characteristically heavy weight of forklift lead-acid batteries continue to 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

[0012] The innovations of the present invention improve in various ways the safe and reliable operation of conventional electric forklifts, in part by enabling forklift rechargeable lithium ion batteries to be replaced with the forklift lead acid batteries for which such forklifts are adapted for use in a conventional manner. Many embodiments of the present invention involve a rechargeable battery assembly that is forklift battery sized but includes a plurality of removable battery modules. The removable battery modules can be individually recharged and can be replaced with one another. Each such battery module is self-contained, equipped with an integrated handle for easy removal from the external assembly, and is 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 purposes or for replacement with a fully charged replacement module.

[0013]

[0013] The preferred adaptation is such that when an operator or maintenance worker desires to recharge the entire assembly, the entire assembly can be removed and recharged in the same manner as a conventional forklift lead-acid battery, 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 allow for 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 the individual battery modules and / or the larger assembly to be recharged not only with a lithium-ion charger, but also easily compatible with recharging with a conventional lead-acid battery charger.

[0014]

[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 at their rear within the housing. The preferred embodiment is double-sided, so that the system has two racks with six modules per rack for a total of 12 modules. The handles of each module are foldable and oriented at the top end of the entire assembly, so that they can be easily accessed during manual removal of the corresponding module.

[0015]

[0015] The 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 release of the battery module. The pins of the low voltage connector incorporate an interlocking feature. The interlocking feature is wired such 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 physical locking system of the housing rack, and successful linking with the communication bus. The interlocking pin loops through the physical latch of the slot to which the module is connected, so that the BOSS module knows that the module is connected. When the module is inserted and the latch is closed, the interlocking pin is shorted by the module ground pin. This mechanism helps prevent arcing in many embodiments of the invention. Without these associated benefits, arcing can lead to overcurrent scenarios, which in turn run the risk of destroying the electrical connector if proper precautions are not taken.

[0016]

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

[0017]

[0017] The battery modules of the preferred embodiment are connected in series and parallel combinations 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 assembled using Tesla's wire-bonded battery manufacturing method. They are connected using comparable techniques. However, there are some key differences with Tesla that have been previously discussed. As mentioned above, this involves the use of LFP battery technology rather than NCA or other LCO battery technology. 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 still allow the forklift to continue operating (because such removal does not reduce the voltage below the full 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. In addition, 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 description 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. [Diagram 2]

[0020] FIG. 1 shows a side view of a Class I forklift in a configuration representative of the prior art, showing the forklift containing conventional forklift lead-acid batteries 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. [Diagram 3]

[0021] FIG. 2 is a side view of a Class I forklift that does not have the conventional forklift lead acid battery of FIG. 1, but instead incorporates a rechargeable battery assembly in accordance with the teachings of the present invention. [Figure 4A]

[0022] 13 illustrates 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 location of the enclosure door and door pins in a half-open position. [Figure 5B]

[0024] Shows the location of the housing door and door pins in a half-open position. [Figure 6A]

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

[0025] Shows the location of the housing door and door pins 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 housing is shown once the door is fully open. [Figure 8A]

[0027] 13 illustrates the engagement and disengagement of a slam latch from a housing in an alternative embodiment. [Figure 8B] 13 illustrates the engagement and disengagement of a slam latch from a housing in an alternative embodiment. [Figure 9A]

[0028] Shows the enclosure door in a partially open position and the location of the module pins. [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 the location of the module pins. [Figure 10B]

[0029] Shows the housing door and module pin locations in the fully open position. [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] A rear view of the housing with the module inserted is shown. [Figure 13]

[0032] 1 shows a rear and side perspective view of a housing with a module inserted therein. [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 of six battery modules connected in parallel to a housing rack is shown. [Figure 20]

[0039] 15 is an elevational view of an alternative embodiment rechargeable battery assembly 220. The assembly 220 is a variation incorporating eight separable battery modules 330, with FIG. 15 showing 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 external 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 cut-away 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 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] 1 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. 13 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] FIG. 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. [Diagram 25]

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

[0047] FIG. 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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] The following description relates to the currently preferred embodiment and should not be construed as describing limitations of the invention, but instead should consider the broader scope of the invention with reference to the claims, which may be attached hereto or may be added or amended later in this or related applications. Unless otherwise indicated, it should be understood that the terms used in these descriptions generally have the same meaning as would be understood by a person skilled 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 such terms generally should not be limited to formal or ideal definitions or conceptually encompassing equivalents unless and only to the extent that a particular context clearly requires.

[0021]

[0049] For the purposes of these descriptions, some wording 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 the alternatives are mutually exclusive in nature. When referring to a value, the term "about" should be used to mean an approximate value (generally "a" or "an" and the like may be used to indicate "one or more" unless expressly indicated otherwise. Such a meaning of "one or more" may be used in conjunction with open language such as "having" or "comprising, including." Similarly, "another" object refers to at least a second or more objects. It could mean elephant.

[0022] Preferred Embodiments

[0050] The following description will be primarily directed to preferred embodiments and may occasionally refer to several alternative embodiments, although it should be understood that many other alternative embodiments fall within the scope of the present invention. Those skilled in the art should appreciate that the techniques disclosed in these examples are believed to represent techniques that work well in the practice of the various embodiments and, therefore, can be considered to constitute preferred modes for those practice. However, the present disclosure In light of this, those skilled in the art should also understand that many modifications can be made to the disclosed embodiments without departing from the spirit and scope of the invention and still obtain an equivalent function or result.

[0023] Housing rack and battery module interface design

[0051] In FIG. 1, a perspective view of the preferred embodiment 10 is shown, 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 battery modules ("modules") 200 arranged vertically. When installed in 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 door 110 prevents 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. In addition, 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 viewing of a display panel 225 on each module 200. The display panels 225 are illuminated using LEDs to indicate the status of each module 200. Further details regarding the display panels 225 are shown in FIG. 15 and described later herein.

[0024] Typical lift truck

[0052] 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 is similar to a Caterpillar Model E6000 forklift, 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 maneuverable 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 of conventional cantilever design to support the load 150, generally extending forward of the fulcrum created by the front wheels 142 of the forklift 130, the heavier the load, the more likely it is 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, in line with its classification as a Class I lift truck, and is dependent on 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) must be properly balanced. 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 typically designed accordingly. The design of such forklifts typically incorporates structure to safely support 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 typically , which is defined in part by a removable or openable panel or the like that partially or completely contains and defines a 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 a partial side panel 136. The seat assembly 135 would normally be located above the forklift battery 160, but has a releasable latch that allows it to be manually pivoted upwardly and away from the forklift battery 160 to allow the operator access to the forklift battery 160 or its compartment 122. Similarly, the panel 136 or other structure is provided to help enclose and define the battery compartment 122, and the panel 136 could also be removable or openable to allow more complete access to that 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 of a conventional forklift battery 160.

[0027]

[0055] A forklift uses a fulcrum (indicated by arrow 91) that is created between the front wheels of the forklift and the floor surface 90 below it. L ) is the moment 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 or not. 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) of such modules 200, each of which includes a number of lightweight lithium-ion battery cells therein. Most preferably, the number of battery cells are of the LFP type. In contrast to the shorter usage times and much longer charging times characteristic of the conventional lead-acid battery 160, the entire assembly 230 can hold an operational charge for about 10 hours without recharging or replacing the individual modules 200, after which a recharge of about 60 minutes is required. Also, due to their lithium-ion chemical composition, each module 200 can be cycled through about six times as many charging cycles as the conventional lead-acid battery 160.

[0029]

[0057] Especially for LFP chemistries, the charging rate, which corresponds to a charging time of one hour or less, is often within the recommended operating limits of the cells. In addition, the easy removal of the module 200 provides the opportunity to charge during breaks. For example, a driver can remove the module 200 during a 15-minute break and perform a substantial recharge during this short interval. The longer operating time of the rechargeable assembly 230 compared to the conventional lead-acid battery 160 also improves workplace efficiency. In the case of the lead-acid battery 160, a large area is allocated for recharging. After the end of an eight-hour shift, the lead-acid battery 160 is removed for recharging and another charged lead-acid battery 160 is inserted. Replacing this system with the rechargeable assembly 230 can save 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 the LFP battery compared to the lead acid battery 160. The lead acid battery 160 has a higher ESR. As a result, they experience a decrease in 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 about six hours into the shift, requiring an additional recharge 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 mounted on 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 oriented vertically, 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 generally 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. The assembly 230 can therefore be described as being "forklift battery sized." Due to its forklift battery sized characteristics, for the forklift 130 as shown, the assembly 230 can safely fit into the same battery compartment 122 as a conventional battery 160. 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] Thus, for use in a Class I electric forklift 130 as shown in FIG. 3, the lithium ion battery assembly 230 is adapted to fit into a Caterpillar E6000 forklift battery compartment 122 for use in place of a conventional lead acid battery 160. More specifically, for the E6000, the lithium ion battery assembly 230 is 34. Fitting approximately to the dimensions of 4 inches (i.e., depth from front to back) by 39.5 inches wide (i.e., lateral dimension when placed on the forklift 130) by 23.3 inches high, the assembly 230 has a minimum weight of 3100 pounds, preferably with a 50 pound margin over the manufacturer specified minimum battery weight requirement.

[0034]

[0062] One 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, which 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. Such removal does not reduce the voltage below the requirements for the forklift 130 to accommodate continued operation despite the removal of one module 200.

[0036]

[0064] Although many aspects of the 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 270C, which is substantially higher than the runaway temperature of more conventional lithium-ion battery cells, NCA or other LCO cells, which typically have a thermal runaway temperature of about 150C. Although the preferred embodiment uses LFP batteries, it should be understood that some aspects of the 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 (LiCoO2), lithium manganese oxide (LiMn2O4, Li2MnO3), lithium nickel cobalt aluminum oxide (LiNiCoAlO2), and lithium nickel manganese cobalt oxide (LiNiMnCoO2).

[0037]

[0065] Within each of the battery modules 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. The wire bonds are accomplished 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 blown to prevent overcurrent in individual cells. In addition, a FET or other form of conventional fuse is 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. The 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. In FIG. 4B, hinge 111 of door 110 is shown 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, the door 110 of the housing 100 is shown in a half-open position. In FIG. 5A, the module 200 is shown protruding from the front end 102 of the housing 100. In FIG. 5B, the pin 113 is shown half-way up the groove 112. When the door 110 is opened, it rotates counterclockwise about the hinge 111. At the same time, the pin 113 moves down the groove 112 towards the bottom of the module 200. It should be understood that the same mechanism exists simultaneously on the opposite side of the module 200. When the door 110 is opened, the module 200 slides out of the housing 100.

[0040]

[0068] Turning to FIG. 6A, the door 110 of the housing 100 is shown in a fully open position, rotated 90 degrees from the closed position. As a result of the door 110 being open, the module 200 is pulled out of the housing 100 and protrudes from the end 102. In FIG. 6A, the carrying handle 205 of the module 200 is clearly visible. The carrying handle 205 is preferably bolted to the module 200, but can be disconnected. In FIG. 6B, the pin 113 is shown to be engaged with the groove 11. 2, allowing the module 200 to be removed from the housing 100.

[0041]

[0069] Turning to FIG. 7A, the module 200 is shown removed from the housing 100 and placed on the door 110. The top of the module 200 has a top protective sheath 203 with an area cut out for viewing the display panel 225. Once the door 110 is in the fully open position, the user can manually slide the module 200 over the door 110 and out of the housing 100 along a track (not shown). The preferred embodiment 10 has low friction slides located under each module 200. Turning to FIG. 7B, the user can manually fold the carrying handle 205 upward and lift the module 200 away from the door 110. The user can 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 show a procedure for removing the module 200 in an alternative embodiment. Turning to FIG. 8A, the disengagement of the slam latch 115 from the housing 100 is shown. The bottom end 116 of the latch 115 is pushed down to release the top end 117 from engagement with the housing 100. In FIG. 8B, the hinge 111' of the door 110' is shown engaging the module 200. The pin 201', permanently attached to the module 200, fits into the groove 112' of the hinge 111'. The pin 201' remains at the bottom of the hinge 111' until the door 110' is opened.

[0043]

[0071] Turning now 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 now 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, the user can manually slide the module 200 on the door 110' out of the housing 100 along a track (not shown). An embodiment has a low friction slide located under 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 actions 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: 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 module 200 and the second module 200. The second set is located between the second module 200 and the third module 200, the third set is located between the third module 200 and the fourth module 200, the fourth set is located between the fourth module 200 and the fifth module 200, and the fifth set is located between the fifth module 200 and the sixth module 200. The sixth set of fans is located between the sixth module 200 and the enclosure 100 wall. A different number of fans are also contemplated by the inventors to provide module cooling. Six sections of the enclosure 100 are hollowed out to expose the rear connections of the modules 200. A 10-pin signal connector 210, a positive connector 211, and a negative connector 212 are visible on the rear of each module.

[0045]

[0073] Turning now to FIG. 13, a perspective view of the preferred embodiment 10 showing the rear of the housing 100 is shown. This view clearly shows that the positive battery terminal 211 and the negative battery terminal 212 protrude from the rear 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 makes 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 the battery voltage are different, the moment the terminals 211, 212 are mated, a momentary high current will flow 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 enabled for safety reasons, particularly to prevent arcing that could damage the electrical connectors, and to disable the battery module 200 before disconnecting it.

[0046]

[0074] For these reasons, the signal connector 210 is the last connector to mate during module 200 insertion and the first 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 still 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 instantly shuts itself off 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 hollowed 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 working properly. If the fault bar 223 is illuminated red, there is a fault in the module 200. There are five bars 223 that are illuminated green, and the five bars 223 indicate the battery charge level of the module 200. The five bars 223 indicate the charge status in 20% increments from 0% to 100% charge range based on the number of LEDs that are illuminated. For example: , one bar indicates that the charge is very low (approximately 20%), and five bars indicates that the module 200 is fully charged (100%).

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

[0077] Turning to Figure 16, a perspective view of the interior of the module 200 is shown. Each battery cell 1710 is wire bonded to a printed circuit board (PCB) 1722. Between the battery cells 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. A 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, 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. The 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 can contain variations in the arrangement or number of battery cells 1710.

[0051]

[0079] Turning now 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. A thermally conductive adhesive 1721a is used between the top of the battery cell 1710 and the top battery tray 1720a. Similarly, the same thermally conductive adhesive 1721b is applied between the top battery tray 1720a and the PCB 1722. The positive wire 1725c and the two negative wires 1725a, 1725b are clearly shown to be wire bonded to the top of the PCB 1722. Turning now to the bottom of FIG. 18, a thermally conductive adhesive 1721c is applied between the bottom of the battery cell 1710 and the bottom battery tray 1720b. Additionally, a thermal gap filler 1726 is used between the bottom of the battery cells 1710 and the bottom of the protective enclosure 204. The gap filler 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 has 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 that are connected in series and parallel via wire bonds and ultimately terminated to the integrated BSS 1700. The wire bonds are completed using a method similar to the Tesla ultrasonic friction welding method. As shown in FIG. The holes formed in the PCB 1722 are used to wire bond the battery cells 1710 to the PCB 1722. At each hole, a tiny wire 1725a, 1725b, 1725c is bonded to both the PCB 1722 and the battery cell 1710. The PCB 1722 is then used to transfer current directly through the interior of the battery module 200. The use of the 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] The preferred embodiment of the BSS 1700 200200 is a real-time battery cell The BSS 1700 uses the information to determine anomalies in individual battery cells and multiple cells in order to diagnose problems. The diagnostic information can be transmitted externally using the communication 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 temperature differences, and ensures that the battery banks are properly balanced. If one battery cell has slightly more or slightly less capacity than the rest of the batteries, over several charge and discharge cycles its discharge level will be different from the other batteries. The BSS 1700 must balance the batteries and prevent over-discharge and over-charge, which can cause damage to the battery modules and ultimately cause complete battery module failure and pose 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 particular 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 percentage of charge that the module 200 currently has. Each module 200 may have a different initial voltage due to differences in battery life or initial charge levels. Each module 200 may also have a different maximum voltage when "fully charged," considering differences in age and usage of the particular module 200. For example, module 200a may have a voltage of 24.0V when fully charged, and module 200f may have a voltage of 23.9V 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 the modules 200a-200f. However, with the control of the BOSS module 901, in scenarios where the voltage of one module exceeds the voltage of the other modules, 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 as the current flows between the battery modules rather than out of the enclosure 100. If high current is maintained for a long time, or if the voltage difference is large enough to produce more current than the bond wires can handle, it may result in battery failure by quickly depleting the battery or opening the bond wires.

[0057]

[0085] Returning to FIG. 19, there are three bus bars in total, to which the modules 200 are connected. The negative terminals 212 of the modules 200 are connected to 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 permission to the battery modules 200 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 employed in the same manner. The communication between the .01 and the module 200 is best understood by describing the low voltage 10 pin connection 210 depicted diagrammatically in FIG. 19 (the actual connector 210 shown in FIG. 14). Four pins are "isolated", five pins are "non-isolated", and one spare pin is not currently utilized but can be adopted later. The term "pin" is also used herein to describe the wires corresponding to their respective pins in the 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 of the system. The isolated wire harness 904 is depicted as an upper dashed line that connects to the module 200c. The isolated wire harness 904 is also connected to the vehicle bus 920. The vehicle bus 920 is a communication network depicted by multiple dashed lines. When the module 200c is inserted into the "slot" of the housing 100, the isolated 5V pin 905 connects to the module 200c and signals to the BOSS module 901. There are two pins 905, 906 for communication between the module 200c and the BOSS module 901. There is a CAN HI pin 906 and a CAN LO pin 907. Finally, there is a ground pin 908 of the insulated wire harness 904.

[0059]

[0087] The non-insulated pins are grouped together as part of a non-insulated wire harness 909. When the module 200c is inserted into the housing 100, the identification (ID) pin 910 is connected to the BOSS module 901 to assign a CAN address in the housing 100 (identifying the slot location of the module 200c in the housing 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 to control the fan power, a pin 913 to control the 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 busbar.

[0060]

[0088] An example of the importance of the BOSS module 901 can be seen during the continuous operation of the forklift and during the replacement of modules 200. The process of inserting a fully charged module 200 while the forklift is operating is known as "hot swapping". Looking at FIG. 19, module 200c is fully charged and inserted with modules 200a-200f already connected. The BOSS module 901 does not give the module 200c permission to connect to the busbar immediately. Module 200c will wait until the current demand of other modules 200 is low before connecting to the busbar. Low current demand refers to the 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 and this is the right 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 gives permission to modules 200 to be connected and disconnected when that state is possible. Each module 200 uses internal MOSFET switches 903a-903f to rapidly open and close the circuit connection from the module 200 to the busbar. 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% and the other modules 200 are above 80%, then module 200f will be disconnected and the other modules 200 will be recharged. It will only reconnect when its power level drops to about 60%.

[0061]

[0089] For at least these reasons, the BOSS module 901 in the enclosure 100 is designed to monitor the charge state of each module 200 as long as it remains connected to the network, and gives permission to disconnect any module 200 that changes beyond some threshold. This allows the forklift to continue operating without impeding performance. Although 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 in the case when the enclosure is empty and the system is completely shut down. When the modules 200 are unplugged from the enclosure rack 100, they are automatically shut down. In an empty enclosure 100, the BOSS module 901 will not power up naturally when a module 200a is inserted. 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, which powers up the BOSS module 901. This process occurs on the 5V bus, separate from the vehicle bus 920. There is no risk of arcing because the current is very low on the 5V bus. 200 While the above figures depict an enclosure rack 100 with one side, the preferred embodiment has a total of 12 modules 200 on both sides, with six modules 200 on each side. In the preferred embodiment, six battery modules 200 are paralleled 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 elevational 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-h that are operably inserted into one of eight identical module bays 301a-h defined within an external housing 300. The housing 300 constitutes 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 for intended use in the forklift 130.

[0065]

[0093] An alternative embodiment has the form of a single housing rack 300 with the capacity to receive and manage eight removable battery modules 330, each of which is interchangeable with the other. 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 to the openings in the removable panels on both sides of the forklift 136. This also simplifies the connection points of the housing rack to just one location. The housing rack 300 provides 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 housing rack 300 of the alternative embodiment is constructed of metal. In a particularly preferred embodiment, the housing rack 300 is constructed of steel, which provides durability. In addition to providing durability, constructing the housing rack 300 from steel adds weight, which allows for the mounting of one or more battery modules. This can help prevent the housing rack 300 from tipping over when several battery modules 330 are removed (especially 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 housing rack 300 is preferably weight-adjusted by attaching heavy weight material thereto (preferably in the form of steel plates placed thereon, but within the enclosure of the housing 300). The additional weight of those steel plates increases the weight of the entire 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). One skilled in the art will appreciate that this counterweight can be made of a heavy weight 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 can include, but are not limited to, different locations of the adjustable counterweight (such as the top of the housing rack) and multiple variations in the materials of the housing rack and counterweight. The chassis rack 300 can be designed such 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 would 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. Alternate embodiments may meet the weight requirement with six to seven modules. Other alternate 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 a poorly aligned battery module 330, the module still weighs 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 method of removal and installation of the module 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 housing rack 300 from the forklift 130. Preferably, there is a module release button 333 on the rear of each battery module 330 that ensures safe disengagement of the module 330 from the housing rack 300, with safe release being considered from a mechanical standpoint. Electrical disengagement occurs with a linking pin configuration. This button is described in more detail below in the section "Housing Rack and Battery Module Interface Design." The front of the battery module also has an indicator that indicates whether the battery is actively engaged or switched off. It will be apparent to one skilled in the art that this indicator could take on a variety of alternative embodiments, including but not limited to a small LED indicator, a light that lights up as part of the button 333, or an LCD display panel on the front of the battery pack that also displays other indicators of the battery health. In this alternative embodiment, the LCD display panel displays indicators used to monitor the battery health, including but not limited to voltage, temperature, and remaining battery life.

[0070]

[0098] FIG. 21 includes another important safety feature. There is an eye hook 226 located in a boss 225 on the top of the enclosure rack assembly 300. An alternative embodiment of the enclosure rack 300 includes eye hooks 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. It will be apparent to one skilled in the art that this boss 225 and eye hook 226 structure mimics the existing eye hook 125 and safety removal mechanism currently used in conventional lead acid battery 160 designs to ensure full backward compatibility. This shape may differ from that shown in FIG. 21. Alternative embodiments may utilize different methods for removing the enclosure rack 300 from the forklift 130, but are utilized such 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 so that the battery pack connection points are visible. The location of this display surface is shown as section 4-4 in FIG. 23. There is another eye hook 226 at the top of the rear of the housing rack 300. At 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 appreciate that other connectors with various numbers of pins can be implemented. The outer casing of the battery module 330 is constructed from a hard lightweight metal. Other materials are contemplated, including but not limited to alloys, composites, and polymers.

[0072]

[0100] 23 is an isometric view of an alternative embodiment of the enclosure rack 300. The configuration has eight (four shown here) battery modules 330 arranged back-to-back in two stacks of four. When installed in the housing 300, each module 330 sits on top of a low friction slide 310 that allows the module 330 to slide in and out of a corresponding bay 307 in the housing 300 for assembly. Also included in this figure are the features previously described for the modules. The front of each module has a handle 335 and the rear has a button 333 for removal. The button on the rack releases the unit for withdrawal from the rack. The pack relies on pin connections (first to connect, last to disconnect) to power on and off the high current terminals. A latch is to hold the batteries in place to prevent loose contact. On the back of each module is seen a six-pin connector 400, a positive connector 401 and a negative connector 402. Additionally, eye hooks 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, with individual 24A depicts the front of an alternative embodiment of the module 330 where both the engagement / disengagement button 333 and the handle 335 are visible. As previously mentioned, the handle 335 is used to safely transport 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 appreciate 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] Handle 335 allows a user to remove and insert the enclosure rack 3 in a manner similar to a drawer. The handles 335 allow the modules 330 to be moved within the 00 and are constructed from a rigid, lightweight metal. Other materials are contemplated, including but not limited to alloys, composites, and polymers. Alternative embodiments may include handles on the back or sides of the individual modules 330. It is contemplated that the battery module 330 may include a handle. Each of these handles is constructed in a manner that allows for easy gripping of the battery module 330 and safe movement of the module. One of ordinary skill in the art will appreciate that the handles added to the modules of alternative embodiments may have battery connection points or hinges that allow for flush 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 The positive terminal 401, 402 is directly wired to the BSS used to monitor the health of the battery. Finally, the positive terminal 401 and the negative terminal 402 are connected to the same battery cells. The positive terminal 401, 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, that it can blindly connect the battery module 330 to the housing rack 300, and that 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 connections that allow for blind sliding connection and disconnection.

[0076]

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

[0077]

[0105] In such an alternative embodiment, the module 330 may include a roller bearing. The modules slide on cylindrical rollers having a frictionless slide 310 and are guided by tracks on either side of the module that are in the same location as the frictionless slide 310. In this embodiment, the rollers and roller bearings are constructed from a lightweight metal. Alternate embodiments can employ various types of roller bearings and rollers constructed from different materials other than metal. It is contemplated that all embodiments of the design will include some method for preventing the modules from moving uncontrollably out of the assembly.

[0078]

[0106] An alternative embodiment of the battery module removal does two things: It is contemplated to accomplish this by having a mechanism to prevent the battery module from being uncontrollably removed and not adding an excessive number of additional moving parts to the battery module design. In FIG. 24A, the alternative embodiment includes two stops 603, 604 located on either side of the module connected to the housing rack 300. There are also two tabs on either side of the modules 605, 606. The stops 603, 604 are for capturing the battery tabs 603, 604 along the rear sides of the module to prevent the battery from suddenly 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 the arrow 608. The module slides along the low friction slides 310 until the battery tabs 605, 606 contact the stops 603, 604 on the housing rack assembly 300. The module 330 must then be lifted over the 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 include, but are not limited to, the back of the module. The battery module 330 may include a stop to allow the battery module 330 to pivot downward 90 degrees so that the battery can be lifted off the rotation rod by a handle on the surface. 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 lifting orientation during removal, thereby reducing the chance of damaging the battery module 330 or the housing rack 300. Alternative embodiments contemplated may include detents or latches on the exterior of the battery, but implemented so as not to fail prior to the end of the battery's life.

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

[0108] 25A and 25B show the upper and lower parts of the battery module 330, respectively. FIG. 3 shows an isometric view of a battery pack 330. Each battery pack 330 is comprised of multiple battery cells that are connected in series and parallel via wire bonds and ultimately terminated into an integrated BSS 700. The wire bonds are completed using a method similar to the Tesla ultrasonic friction welding method. While wire bonding is widely used in other contexts such as integrated circuits and discrete electronic devices, the battery industry has incorporated wire bonding to allow larger gauge wires to be predicated. Both figures show multiple battery plates 701-709. The holes shown in each plate are used to wire bond a battery cell 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 transfer electrical current directly through the interior of the battery module 330. The use of plates prevents the entire battery module 330 from failing if one battery cell fails, since the other cells are still connected to the plate.

[0081]

[0109] The cells are made up of plates 701 to 709 as shown in FIGS. 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 positive and negative battery cell configurations. In the case of 702-708, this is approximately half the geometric area of ​​the space. In an alternative embodiment, each of these internal plates contacts 50 battery cells, half of which are negative contacts and the other half are positive contacts, with the most negative plate and the most positive plate each contacting 25 cells. Plates 701, 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 would incorporate 200 LFP battery cells. Alternative embodiments may include variations in the arrangement or number of battery cells. This also implies that the plates of alternative embodiments may have a different number, arrangement or geometry than the alternative embodiments.

[0083]

[0111] The current flow through the battery cells travels around the inside of the module 330. 25A, alternating between the top and bottom of the module 330. 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 25 negative battery cell ends, and in 702b, the plate has contacts with the 25 positive cell ends. Then, The negative end of the battery cells of plate 703 are the same cells that have a positive connection with portion 702b of plate 702. These cells have a negative connection with plate 703. The other half of plate 703 is located in area 704a. This area contains the positive contact with the battery cells. Area 704b of plate 704 continues the pattern and has a negative connection with plate 705. The contact of plate 705 here is negative. The other half of plate 705 is positively connected and the cell also has a negative connection in area 706a of plate 706. Area 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 with 708a. The 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 collects data on the modules 330 including cell voltage, current and temperature. Monitor health. With regard to monitoring, some embodiments may incorporate a display with multiple LED lights for the purpose of monitoring the status of the battery modules 330. For example, the display may have seven LEDs, five of which indicate charge status in 20% increments from 0% to 100% charge based on the number of LEDs illuminated. The other two LEDs may indicate status and trouble codes based on the color of illumination and / or by LED blinking sequences or patterns, with different blinking sequences or patterns associated with specific trouble codes. Additionally, each display may incorporate a push button that may be used to query the status of a particular battery module 330 and may also be used to troubleshoot the battery module 330 by the number of times the button is pressed or by the time the button is held down. Each figure (FIGS. 25A-25B) shows the BSS 700 and the flexible cables 710 wired from the 6-pin connector 400 to each section of the battery cells. A flexible cable 710 is used in an alternative embodiment to wire all diagnostics to measure temperature, current and voltage. Additionally, each module 330 contains field effect transistors (FETs) 711 in series with the battery cells to ensure proper power handling. These switches are an aspect of the alternative embodiment that allows the module to be removed from the enclosure rack 300, as well as function as an active and resettable fuse element. The number of FETs 711 is based on the power capacity of the cells, and upon removal of the module 330 from the enclosure rack 300, the FETs 711 ensure that no power is applied to the terminals. One alternative embodiment has 20 FETs 711, but other alternative embodiments of this design having different power capacities would of course have a different number of FETs or equivalent.

[0085]

[0113] An alternative embodiment of the BSS 700 uses real-time battery cell information: This information is compared to a set of reference values. The BSS 700 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 communication 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 and records the voltage, temperature, and BSS compensates for 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 battery, over several charge and discharge cycles its discharge level will be different from the other batteries. 700 must balance the batteries and prevent over-discharging, over-charging and deep-discharging, which can cause damage to the battery module and ultimately cause complete battery module failure and pose a safety risk.

[0087]

[0115] In an alternative embodiment, a Controller Area Network (CAN) communication protocol is used. A CAN protocol is used as the primary BSS. The CAN bus has error detection and fault tolerance, but has some significant material costs and communication overhead. For the transmission of information, various communication systems can be implemented. Other alternative embodiments can use industrial transmission interfaces such as a serial peripheral interface (SPI), DC-BUS, or a local interconnect network (LIN bus). In alternative embodiments, the CAN can interface with each BSS to effectively monitor and control the performance of the entire battery enclosure rack. This prevents inter-battery performance issues and uses 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. Moreover, a separate CAN scheme can be implemented, which allows communication with the battery modules at the "top" of a stack of battery modules, which may be at a potential that is somewhat higher voltage than the battery modules lower in the stack.

[0088] Housing rack and battery module interface design

[0116] FIG. 26 is a schematic top view of a battery module, showing removal and installation in a rack. 26 shows the mechanism for removal and installation. The battery module 330 is removed by pressing a button 333 on the external handle. The button 333 is to ensure that the module 330 stays in place during the operation of the forklift. 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 are the first to engage and the last to disengage. In FIG. 26, 800-803, 401, 402 are symbolic representations for illustration purposes. Alternative embodiments of this portion of the system are different sizes and more complex but accomplish the same task.

[0089]

[0117] Removable battery modules in slot-like bays 307 of rack 300 To install 330, the user first manually places the rear of the battery module 330 into the opening of the corresponding bay 307 and then manually slides it back into the bay. Once the module 330 is slid far enough that the rear 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. It is contemplated that the connector 800 is 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 housing 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] In addition, before completely removing the battery module, There is a need to safely disconnect and engage the battery module from the enclosure rack when the battery module is in use. Arcing can result in overcurrent and destruction of the battery if proper precautions are not taken. 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 the voltages of each are different, the moment the connector 800 and connector 801 physically mate, a momentary high current will flow to equalize the potentials. 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 accomplished through multiple 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, which switches the battery on only when the battery is fully engaged with the connector. The switch The relative dimensions of the switch and power connector are such that the switch protrudes from the back surface of the battery sufficiently to be disengaged before the battery module is completely disconnected.

[0091]

[0119] Another alternative method is by electronic signals. 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 is substantially shorter than the battery terminals so that during the removal process, the pin connector is disconnected but the battery terminals still remain connected. At this point, the battery module detects that it is no longer connected to the housing rack via the pin connector and instantly shuts itself off before the battery terminals are disconnected. Those skilled in the art will appreciate that alternative embodiments may employ mechanisms other than those employed in FIG. 26 or those described as alternative configurations. The purpose of the mechanism is for safety, specifically to prevent arcing.

[0092]

[0120] An additional feature of the alternative embodiment is that it is designed for use with a forklift 130. This is reflected in the battery module 330 being compatible with prior art chargers used to recharge the conventional battery assemblies 160 (shown in FIG. 2) that have been designed for use in a battery module 330. Due in part to Applicant's design of the lithium iron phosphate cell module 330, when assembled into a module in accordance with an embodiment, which 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 the chargers that recharge the conventional forklift batteries 160 currently used and already installed in warehouses.

[0093] Charging management system integration

[0121] FIG. 26 is a schematic diagram of an alternative embodiment, which includes 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 set forth 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 levels. In the example of FIG. 26, two modules have a fully charged voltage of 36.0V and the other module has a lower voltage, as set forth.

[0094]

[0122] However, in the case of BSS 901 control, the voltage of one module may be different from that of the other modules. In scenarios where the voltage of the battery module is exceeded, 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 as the current flows between the battery modules rather than out of the housing rack. If high current is maintained for an extended period of time or if the voltage difference is large enough to produce 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 The battery module is designed to monitor the voltage of each module as long as it is connected to the work, and will disconnect any module that changes above a threshold of 0.10V. This allows the forklift to continue operating without impeding performance. A specific 36V battery module is used as an example, as alternative embodiments can use a variety of voltages depending on the needs of a particular lift truck.

[0096]

[0124] Another alternative embodiment of the battery monitoring system architecture is 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 that has a microcontroller, a CAN interface, and a 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 ) is on a PC board within each battery module. The BSS also contains a CAN transceiver and a galvanic isolation transformer. Each module communicates through the MBSM non-isolated SPI-compatible serial interface. This structure requires three or four conductor cables to be connected between the battery modules. A single microcontroller controls all the battery monitors through the bottom monitor integrated circuit. This microcontroller also acts as a gateway to the forklift's main CAN bus.

[0098]

[0126] Another contemplated embodiment is to provide a monitor and control system within any battery module. The BSS does not have any circuitry. One PC board has three MBSM integrated circuits (for three modules), each of which connects to a battery module. The MBSM devices can communicate through a non-isolated SPI-compatible serial interface. One microcontroller controls all the battery monitors through a 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] The present invention has been described with reference to the above disclosed embodiment. The description is provided merely as an illustration and is not intended to be construed as limiting the present invention. For example, although a Class I forklift is so referred to, it should be understood that some 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 alternative forms that are not expressly mentioned or even recommended herein. The foregoing description should enable those skilled in the art to make and use what is currently considered to be the best mode of the invention, but 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. It should be considered that the drawings and detailed description herein are not intended to limit the invention to the particular forms and examples disclosed. On the contrary, the invention encompasses many additional modifications, variations, rearrangements, substitutions, alternatives, design choices and embodiments that will be apparent to those skilled in the art without departing from the spirit and scope of the invention.

[0101]

[0129] Accordingly, in all respects the drawings and detailed description herein are to be construed as limiting. It should be understood that the present disclosure is not intended to be limited to the specific forms and examples disclosed, and that the disclosure should be regarded as illustrative rather than limiting. In all cases, all substantially equivalent systems, articles and methods are to be regarded as being within the scope of the present disclosure, 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 modular rechargeable battery system for use as a replacement or replacement for conventional lead acid batteries in a battery powered industrial forklift truck, the modular rechargeable battery system adapted to power the battery powered industrial forklift truck, a) a plurality of battery modules, each battery module of the plurality of battery modules including a positive terminal, a negative terminal, and a plurality of lithium ion battery cells, the plurality of lithium ion battery cells being electrically coupled within each one of the plurality of battery modules to provide a coupling potential between the positive terminal and the negative terminal of each one of the plurality of battery modules; b) an enclosure having a plurality of bays, each of the bays configured to receive one of the plurality of battery modules, the enclosure being sized and adapted to operably fit within a battery compartment of the battery powered industrial forklift truck, each of the plurality of bays including a pair of power connections for mating with the positive and negative terminals of one of the plurality of battery modules when the housing receives the one of the plurality of battery modules; c) the housing further including a conductor and an external power terminal, the external power terminal being oriented and adapted to operatively connect to a power circuit of a battery powered industrial forklift truck, the conductor having a layout for connecting power from the pair of power connections of the plurality of bays to the external power terminal; d) a processor for monitoring the modular rechargeable battery system and for controlling a power switch such that operating power is directed through the conductor to the external power terminals, the processor being adapted to direct the operating power to the external power terminals when not all of the bays have a corresponding one of the battery modules operably received therein, thereby enabling the battery powered industrial forklift truck to be provided with operating power when not all of the bays have a battery module received therein.

2. 10. The modular rechargeable battery system of claim 1, wherein the housing is sized and adapted to operably fit within a battery compartment of a Class I forklift and each of the battery modules has a weight of 51 pounds or less.

3. 10. The modular rechargeable battery system of claim 1, wherein each of the lithium ion battery cells is interconnected to a printed circuit board (PCB) above the lithium ion battery cells via wire bonds.

4. 4. The modular rechargeable battery system of claim 3, wherein the wire bonds for each of the battery cells include a wire bond connected to the positive terminal of the battery cell and one or more wire bonds connected to a top edge of the battery cell, the edge being electrically integrated with the negative terminal of the cell.

5. 10. The modular rechargeable battery system of claim 1, wherein a thermally conductive gap filler is in thermal contact with a bottom surface of said lithium ion battery cells, said thermally conductive gap filler being electrically non-conductive.

6. 5. The modular rechargeable battery system of claim 4, wherein each of said battery module bays is further configured such that said one battery module is received within said battery module bay in a vertical orientation.

7. 5. The modular rechargeable battery system of claim 4, wherein each of said battery module bays is further configured such that said one battery module is received within said battery module bay in a horizontal orientation.

8. 6. The modular rechargeable battery system of claim 5, wherein each battery module bay is defined by two lateral partitions of the housing and an exterior door, the door having a latch for securing the door in a closed position, the door further having a hinge and an interlocking pin for opening and closing the door.

9. 10. The modular rechargeable battery system of claim 1, wherein each battery module of said plurality of battery modules is individually rechargeable.

10. 10. The modular rechargeable battery system of claim 1, further comprising a battery management system including a controller area network (CAN) configured to receive and monitor diagnostic information from the plurality of battery modules.

11. 10. The modular rechargeable battery system of claim 9, wherein the battery management system is further configured to enable and disable one or more battery modules during operation of the modular rechargeable battery system based at least in part on the diagnostic information.

12. 10. The modular rechargeable battery system of claim 1, wherein each of said battery modules includes a pin connector, a positive battery terminal, and a negative battery terminal.

13. 13. The modular rechargeable battery system of claim 12, wherein the pin connectors are recessed from a surface of the battery module relative to the positive and negative battery terminals.

14. 10. The modular rechargeable battery system of claim 1, wherein the lithium-ion battery cells are lithium iron phosphate (LFP) battery cells.

15. a) each of said battery modules has a weight of less than 51 pounds; b) each of said battery modules is individually rechargeable; c) each of the lithium ion battery cells is interconnected via wire bonds to a printed circuit board (PCB) on one side of the lithium ion battery cells; d) thermally conductive material is located between a top surface of the lithium ion battery cell and an upper battery tray, between the upper battery tray and the PCB, and between a bottom surface of the battery cell and a lower battery tray, the thermally conductive gap filler being electrically non-conductive; e) a thermally conductive gap filler is in thermal contact between the underside of the battery cell and the module enclosure to enable heat transfer from the cell to the enclosure for thermal management purposes, the thermally conductive gap filler being electrically non-conductive; f) the housing includes a plurality of battery module bays, each of the battery module bays configured to receive one battery module therein, each of the battery module bays further configured to receive one of the battery modules in a vertical orientation; g) each of said battery module bays is defined by two lateral partitions of said housing and an exterior door, said door having a latch for securing said door in a closed position, said door further having a hinge and an interlocking pin for opening and closing said door; h) the battery management system includes a controller area network (CAN), the controller area network (CAN) 1) receiving and monitoring diagnostic information from the plurality of battery modules; 2) enabling and disabling one or more battery modules during operation of the modular rechargeable battery system based at least in part on the diagnostic information; i) each of the battery modules includes a pin connector, a positive battery terminal, and a negative battery terminal, the pin connector being recessed from a surface of the battery module relative to the positive and negative battery terminals; 10. The modular rechargeable battery system of claim 1, wherein: j) said lithium-ion battery cells are lithium iron phosphate (LFP) battery cells.

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