Improved flooded motive and deep cycle battery cells

Abstract

Methods for operating a flooded electrolyte battery cell used in motive service to prevent the loss of water. When charging the cell, water in the electrolyte decomposes electrolytically to oxygen and hydrogen gases. The method includes catalytically recombining the oxygen and hydrogen gases to water vapor, inhibiting venting of the oxygen and hydrogen gases and water vapor from the cell, providing fluid communication between the catalyst and the electrolyte for the oxygen and hydrogen gases and water vapor, and hygroscopically absorbing the water vapor into the electrolyte. Devices and battery cells for carrying out the method are also provided.

Description

Docket No. 074455.00299IMPROVED FLOODED MOTIVE AND DEEP CYCLE BATTERY CELLSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to and the benefit of U.S. Serial No. 63 / 708,131 filed on October 16, 2024, which is incorporated by reference in its entirety.BACKGROUNDField of the Invention

[0002] The present invention relates to improvements to flooded battery cells, and more particularly, the use of catalysts to minimize and eliminate watering maintenance in motive and deep cycle flooded cells.Background

[0003] A battery is a device that converts chemical energy into electrical energy through electrochemical reactions. A battery typically consists of two or more cells electrically connected in series to form a single battery unit. Multiple batteries, each with multiple cells, can be connected electrically to one another in series and in parallel to provide the desired amount of electrical output. While the terms “battery” and “cell” are used interchangeably, as the basic unit of a battery, the individual cell is the focus of the discussion below.

[0004] Various types of battery cells are known for use in different applications. Exemplary types of battery cells include flooded lead acid battery cells and sealed lead acid battery cells. Exemplary uses of batteries include stationary batteries on standby to provide backup and emergency power should the regular electrical grid fail, and motive batteries, which include traction batteries, for use in applications such as for forklifts and other vehicles, to power motors, and which also includes cells used in deep cycle applications whereby the cells may be discharged in use up to 80 percent and sometimes more. Improvements to battery cells in standby use with the use of catalysts are discussed in International Application No. PCT / US24 / 24132 filed April 11, 2024, which application is incorporated herein by reference in its entirety. Catalysts developments are believed to be capable of providing significant improvements to motive and deep cycle cells, even though they are used in very different applications and with very different charging profiles than standby cells. The present invention relates to improvements to motive and deep cycle flooded battery cells, and more particularly, the use of catalysts to minimize, delay and / or eliminate watering maintenance in such cells as described herein. The terms motive and deep cycle cells are used synonymously herein.

[0005] The construction of a traditional flooded battery cell is shown schematically in FIG. 1. It has at least two electrodes or plates: a positive and a negative plate. Each of these plates is made of a current-conducting grid and an energy-storing active material. The plates are178184658Docket No. 074455.00299 immersed in a bath of liquid electrolyte, such as an aqueous solution of dilute sulfuric acid as used in lead acid battery systems. A non-electrically conducting porous separator is positioned between the plates to prevent the plates from contacting one another, preventing electrical short circuiting within the cell, but which is permeable to the electrolyte. The electrolyte and the plates are housed in a liquid tight container having a top cover, and two terminals extending through the cover - a positive terminal and a negative terminal for connecting the cell to the electrical load or system to be powered.

[0006] A traditional flooded cell is also vented to the atmosphere through a simple orifice or opening (gas vent) typically provided in the cell cover. The vent provides an uninhibited and continuous opening that allows the exchange of gases between the inside of the cell and the surrounding atmosphere, permitting gases generated within the cell to escape to the surrounding atmosphere. It is common to provide a vent cap (not shown) over the gas vent that has openings to allow the gases to vent freely, but which is configured to receive a watering nozzle for adding water to the cell.

[0007] As in any lead acid cell, when being charged, i.e., “during the charging cycle”, water in the sulfuric acid electrolyte decomposes to oxygen and hydrogen gases through the process of electrolysis. In flooded lead acid cells, these gases escape the cell to the atmosphere through the vent. This electrochemical decomposition of the water and the venting of the resulting hydrogen and oxygen gases causes a loss of water from the electrolyte, lowering the electrolyte level within the cell. Flooded cells can also lose water through evaporation, the vaporized water venting from the cell to the atmosphere and adding to the water loss. The warmer the environment of the cell, the greater the evaporation rate. With such cells, water maintenance is required to replenish the water loss and maintain the proper electrolyte level. This is typically done by the addition of distilled water. Failure to maintain the proper electrolyte level can expose the plates above the electrolyte, which can reduce the electrical output of the cell and shorten the cell’s life. Water maintenance programs to monitor the electrolyte levels of the individual cells and add water as needed are costly. As other components of a battery cell do not require maintenance as regularly, water maintenance is one of the major costs for the upkeep of battery systems, and failure to do so is a major reason such cells fail prematurely.

[0008] Significant improvements to battery cells have been made to minimize water loss. One improvement is the valve regulated lead acid cell, or “VRLA” cell, a form of a “sealed cell”. These are similar to flooded lead acid cells with some key differences. One difference is that the plates are not immersed in a bath of liquid electrolyte, but are in contact with an immobilized electrolyte (not a bath of liquid), that has pathways allowing gases within the cell to have direct and easy access to the cell plates for minimizing water loss as described below. In one form of2178184658Docket No. 074455.00299 a VRLA cell, the plates are sandwiched between sponge like separators that are made usually from an absorbent glass fiber. Most of the electrolyte is absorbed in the separators. This type of VRLA cell is called the “absorptive glass mat” type or AGM cell. Another type of VRLA cell is the “gel cell” in which liquid electrolyte of the type used in a conventional flooded cell is replaced by a gelled electrolyte.

[0009] The VRLA cell minimizes water loss by providing for an internal oxygen recombination cycle within the cell, also referred to as the “internal oxygen cycle”, which recombines the oxygen and hydrogen gases to water. As the plates are not immersed in a bath of liquid electrolyte, oxygen and hydrogen gases produced by the electrolytic decomposition of water can easily migrate or diffuse through the immobilized electrolyte to the plates where the gases are recombined to water through the internal oxygen cycle. The internal oxygen cycle is not generally applicable for the flooded cell as gases cannot readily migrate or diffuse through the bath of electrolyte to the plates, but instead bubble up through the liquid electrolyte and vent from the cell to the atmosphere.

[0010] The second key difference between the VRLA cell and a flooded cell is that the VRLA cell is not vented to the atmosphere, but instead has a one-way valve that provides for pressurization of the cell, typically between 2 and 5 psi, to maintain the gases within while having a one-way pressure relief valve to prevent over pressurization that could damage the cell. The one way -valve keeps atmospheric air from entering the cell where the excess oxygen in the air, out of balance with the ratio of oxygen and hydrogen gases normally in the VRLA cell, would have direct access to the plates, causing self-discharge of the negative plate and poisoning of the cell. Atmospheric air entering a flooded cell is not an issue as gases cannot migrate or diffuse through the bath of liquid electrolyte to the plates, although this prevents flooded cells from using the internal oxygen cycle to recombine gases. Furthermore, VRLA cells tend to be smaller and have less capacity to provide continuous power than flooded cells.

[0011] A popular use for battery cells, particularly flooded lead acid cells, is motive service, which includes heavy duty and deep cycle service (in some cases up to 80% discharge or more). Such cells are constructed to be used for many cycles of discharging and charging, generally measured as charge cycles. Motive cells are typically designed to last between 1000 and 2000 charge cycles or more. By way of example, such cells are used to power forklifts, golf carts, industrial sweepers and scrubbers, pallet jacks, marine use, motors, and the like. They are also used to store excess energy generated by solar energy systems during periods of low demand, and then release that energy during periods of high demand. Unlike flooded standby battery cells, which are used only intermittently or for short periods of time before being continuously recharged by long term float charging methods described in International Application No.3178184658Docket No. 074455.00299PCT / US24 / 24132, flooded motive cells are designed to provide sustained power over relatively longer periods of time, and in many cases until deeply discharged, in some cases up to 80% discharged or more, before the cells are removed from service and recharged fairly quickly back to full charge to be put back into service. These cells are used to power the device (the “load”) until the cells need recharging, at which time the load is removed from service and its battery cells recharged. Depending on the type of load device, the battery cells can be charged in place on the device, or the battery cells can be removed from the device to a charging station for charging while a fresh fully charged battery is connected to the load for continued use of the device.

[0012] For example, motive battery cells mounted on a forklift are used to power the forklift until the cells are discharged to a point requiring recharging, at which time a battery cable connecting the cells to the forklift electrical system is unplugged and then plugged into a charger that provides the power to recharge the cells in accordance with a predetermined charging method before it can be put back into service. Once the cells are fully recharged, the charging is terminated. Modern charging devices typically automatically terminate the charging when certain predetermined cell conditions are reached as discussed below. After the charging is terminated, the cells may be allowed to cool down as the charging process can increase the temperature in the cells. Water may also be added at this time to replace any water loss before the cells are placed in service again. Alternatively, the battery cells can be removed from the forklift to a charging station where the battery cells are connected to the charger device for recharging, while freshly recharged battery cells are mounted to and connected electrically to the forklift for continued use of the forklift.

[0013] As another example, batteries used with golf carts are mounted to the golf cart and not normally removed unless for maintenance or replacement. Golf carts also include a charging device capable of being plugged into a typical 120- or 240-volt outlet. The golf cart is typically used during the day and recharged at night when not in use, or after a particular use is over, by plugging the charger electrical plug into the outlet. Once the charging is completed, most chargers terminate automatically, after which the charger can be unplugged from the outlet so that the golf cart can be returned to service.

[0014] There are a number of charging methods for flooded cells of the type used with motive service, depending on the manufacture and particular service. For example, there are constant power charger systems, also referred to as tapered current systems, in which current to the cells starts at a relatively higher value and voltage applied starts at a relatively lower level, with the current tapering lower as the applied voltage increases, maintaining the constant power. Another type of charging system begins with a constant relatively higher current until the4178184658Docket No. 074455.00299 charger voltage reaches a preset upper limit, at which time the voltage is held constant while the current decreases until reaching a lower preset limit at which time the current is held constant with increasing voltage. For many charging systems, the charging cycle is terminated automatically by a timer control after a preset voltage limit is reached, or when the rate of change of voltage reaches a predetermined value (and also the rate of change of current for constant power type chargers).

[0015] At some point during charging with typical charging systems, as the cell’s charge capacity increases, but before the charging terminates, the charging voltage reaches a level where gassing of the electrolyte begins, i.e., the water in the electrolyte decomposes to hydrogen and oxygen gases through the process of electrolysis. This is believed to begin at about 2.37 volts per cell, which is higher than the open circuit voltage of the cell. The open-circuit voltage for a fully charged lead acid cell is typically about 2 to 2.05 Volts. (Open-circuit voltage is the difference of electrical potential between the positive and negative terminals of the cell when disconnected from any circuit).

[0016] In addition to the normal charging methods, for battery cells used in motive service, it is common to overcharge the cells for a limited amount of time with each charge cycle or after a predetermined number of charge cycles as doing so provides benefits to the long-term health of the cells and helps ensure a full charge. However, overcharging occurs at the end of the charging cycle after the cell likely reached its maximum charge and uses a charge voltage higher than the voltage at which gassing begins in the cells, thus creating additional gassing that vents from the cell, and thus a loss of water.

[0017] Cells used in motive service can also be opportunity charged. Opportunity charging is using any available idle time to provide some top off charge during that available time period. Its sole purpose is to extend the available period of service before a full recharge is required. A version of opportunity charging is called fast charging, which applies a significantly higher current into the battery cell than that of a normal charge current to add more charge into the cell during the available time period. Such opportunity charging, including fast charging, generally involves voltage levels that cause electrolytic decomposition of the water in the electrolyte and thus creates gassing, which vents, and thus a further loss of water.

[0018] Equalization charging, i.e., periodically applying a high voltage to intentionally overcharge a cell after it has been fully charged, is used to help improve the charge capacity of the cell. The higher voltage, generally in the range of about 2.65 volts per cell, is used to purposefully gas the electrolyte, creating bubbles that help eliminate stratification of the electrolyte and sulfation on the plates. While this process is believed beneficial to the cell, it5178184658Docket No. 074455.00299 causes more water loss. Equalization charging should not be performed on non-flooded cells such as VRLA cells.

[0019] As noted above, the charging cycle of motive cells cause electrolytic decomposition of the water in the electrolyte to oxygen and hydrogen gases. Unlike some other types of batteries, however, higher charging voltages are involved with motive cells which leads to higher rates of gassing, which gases escape to the atmosphere through the cell vents. Such cells thus lose water at relatively high rates as compared to other cells. Although not as prevalent, water can also evaporate from the cells given that the cells are open to the atmosphere through the vents.

[0020] Accordingly, motive and deep cycle cells require regular watering maintenance, after each charge cycle in some cases, and after a predetermined number of charge cycles in other cases. This involves inspecting each cell by removing the vent cap and adding water to each individual cell as needed, which can be timely and costly. For batteries that comprise many cells, single-point watering systems can be used to add water to the water system at a single point to be distributed to each of the cells until each cell reaches the desired water level. Such systems, however, can be costly. Moreover, inspection of the cells requires removal of an injector valve in each cell used with the watering systems and then replacing these valves before carrying out the watering process. Another problem with ongoing watering is the potential exposure of sulfuric acid to persons doing the watering, particularly from spills due to overwatering. Additionally, sometime vent caps are not put back properly, which can lead to leaks, splashing and spilling of electrolyte. Furthermore, it is not uncommon for required maintenance to be done poorly or not at all. For example, many owners of golf carts are not proficient at properly maintaining the batteries. Improvements to such cells to minimize, delay or even eliminate watering would be beneficial.

[0021] Accordingly, the present invention relates to improvements to the design and operation of motive and deep cycle flooded cells.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. l is a schematic cross-sectional view of a traditional flooded cell shown connected to a load;

[0023] FIG. 2 is a schematic cross-sectional view of a flooded cell in accordance with the present invention shown connected to a charger;

[0024] FIG. 3 is an elevation view of a recombination device in accordance with the present invention;

[0025] FIG. 4 is a cross-sectional view of the recombination device of FIG. 3 taken along line 4-4;6178184658Docket No. 074455.00299

[0026] FIG. 5 is an exploded perspective view of the recombination device of FIG. 3;

[0027] FIG. 6 is an exploded elevational view of the recombination device of FIG. 3;

[0028] FIG. 7 is an enlarged perspective view of the cap and top cover shown in FIG. 5;

[0029] FIG. 8 is a perspective view of the catalyst device shown in FIGS. 4 and 5;

[0030] FIG. 9 is a cross-sectional view of the catalyst device of FIG. 8;

[0031] FIG. 10 is a partial cross-sectional view of the catalyst device of FIGS. 8 and 9 showing the outer side of the end caps;

[0032] FIG. 11 is a perspective view of another embodiment of a catalyst device;

[0033] FIG. 12 is a cross-sectional view of the catalyst device of FIG. 11;

[0034] FIG. 13 is a perspective view of an alternative embodiment of a recombination device;

[0035] FIG. 14 is an exploded perspective view of the recombination device of FIG. 13;

[0036] FIG. 15 is a cross-sectional view of the recombination device of FIG. 13;

[0037] FIG. 16 is a schematic cross-sectional view of a cell with the recombination device of FIG. 3 shown connected to a charger;

[0038] FIG. 17 is a schematic cross sectional view another embodiment of a recombination device;

[0039] FIG. 18 is a schematic cross-sectional view of yet another embodiment of a recombination device;

[0040] FIG. 19 is a schematic cross-sectional view of another embodiment of a recombination device; and

[0041] FIG. 20 is a schematic diagram illustrating the reaction cycle taking place in a method of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0042] With reference to FIG. 1, a vented flooded cell 10 suitable for use with the present invention has a container 12 having a container bottom 14, side walls 16, and cover 18. Contained within the container 12 is a suitable liquid (flooded) electrolyte 20. The electrolyte 20 has a liquid level 22 defined by a surface 23 of the electrolyte 20. Above the liquid level is a gas space 24 in which oxygen and hydrogen gases generated in the cell 10 collect. The gas space 24 is defined by the electrolyte level 22, the inner surface 16a of the container walls 16, and the inner surface 18a of the container cover 18. A vent opening 26 in the container cover 18 is positioned to allow fluid communication between the gas space 24 and the environment or atmosphere 28 outside the cell 10 as in prior art cells discussed previously.

[0043] A positive electrode 30 having an active material is positioned within the container 12 immersed in the electrolyte 20. A negative electrode 32 having an active material is also positioned in the container 12 immersed in the electrolyte 20, and in spaced relationship from7178184658Docket No. 074455.00299 the positive electrode 30. Such electrodes 30, 32 are typically in the form of plates, which term will be used synonymously herein with the term electrodes, and which can come in various shapes such as flat or tubular plates. A porous separator 34 is positioned between the electrodes 30, 32 to prevent the electrodes from contacting one another, but is permeable to allow the electrolyte 20 to pass freely therethrough. As discussed above, the electrodes should preferably remain fully immersed in the electrolyte 20, i.e., fully covered, to avoid potential problems.

[0044] The positive and negative electrodes 30 and 32 are connected electrically to respective positive and negative terminals 36 and 38, typically by respective positive and negative straps 40 and 42, as they are commonly referred to in the art.

[0045] While a motive flooded cell 10 is similar in construction to the flooded cells used in other services, such as standby service, there are differences due to the more severe service seen buy motive cells. For example, the positive plates 30 of motive cells, made of lead, will contain a higher percentage of the alloy antimony, typically 3-6% antimony, than those of standby cells, which have about 2% or less of antimony. Antimony improves the strength of the lead plates and helps stabilize the active material in the plates, improving the plate performance in motive cells that are cycled (discharge / recharge cycle) many times over the life of the cells, typically between 1000 and 2000 charge cycles or more depending on the operating environment, application, and how well the cell is maintained. On the other hand, higher antimony content can increase the water decomposition rate of the electrolyte during charging, which is further discussed below, and antimony released from the positive plate can negatively impact the negative plate and thus the performance of the cell.

[0046] In use, motive cells are used to power devices and vehicles, and can be deeply discharged followed up with a full recharge, which cycle of discharging and recharging can continue over a thousand cycles. Unlike standby batteries, they are not recharged over many days, i.e., using a float charge, but must be recharged more quickly to be used again as soon as possible. As noted previously, for example, golf carts are used during the day and then recharged at night to be used the following day. Forklifts are used until the battery is deeply discharged and then must be recharged quickly for reuse again. Eight hours of recharging to reach full charge is not uncommon. The quicker recharge times can require higher voltages during charging as compared to float charging of standby batteries which can take many days for recharging and then remain on float charge until needed for backup power, whereas the charging of a motive cell is typically terminated once the cell is fully charged, and then is returned for service where it is discharged again.

[0047] It is believed that the flooded cells 10 that will be used most widely with the present invention will be of the lead acid type that include the following: a positive electrode 308178184658Docket No. 074455.00299 comprising a conductive material such as a lead alloy, and active material comprising lead oxide (PbCh); a negative electrode 32 comprising lead, preferably finally divided particles of substantially pure lead, referred to in the industry as “sponge lead”; and an aqueous electrolyte 20 of dilute sulfuric acid. However, the present invention described herein is applicable to other flooded battery types that use an aqueous electrolyte, such as Nickel / Cadmium and Nickel / Metal Hydride batteries, both of which use an electrolyte of potassium hydroxide.

[0048] The cell 10 in FIG. 1 is shown connected to a load 154, which could be a forklift, golf cart, or any other motive device powered by motive cells. For illustration purposes, a single cell 10 is shown, it being understood that motive batteries are made up of multiple such cells connected together electrically to obtain the desired power as is known in the art. For example, a typical 12-volt (“V”) forklift battery would have an arrangement of 6 such cells; a 24 V battery would have 12 cells; a 32 V battery would have 16 cells, a 36 V battery would have 18 such cells; and a 48 V battery would have 24 cells. While most batteries have multiple cells, the present invention applies to each cell of the battery and thus a single cell is illustrated in the figures.

[0049] An electrical cable 202 connects the cell’s positive and negative terminals 30, 32 to the load 154 through couplings 206, 208, which connects the cell wire 202 to the load wire 200. Also illustrated in FIG. 1 is a charger 150 having electrical cable 204 and connector 210. For powering the load 154, the battery cell is connected to the load through battery cable 202 connected to the load cable 200. When it is time to recharge the cell 10, the battery cable 202 is disconnected from the load 154 at the respective couplings 206, 208, and connected to the charger 150 via electrical cable 204 through couplings 206, 210. The battery cable 202 is shown partially in broken line connected to the charger 150 for illustration purposes as the cable 202 of the illustrated embodiment is connected to the load 154 via the solid line cable 202, and can be disconnected from the load 154 and connected to the charger 150 as illustrated via the broken line 202. Once the charging cycle is completed, the battery cable 202 would be disconnected from the charger 150 and reconnected to the load 154. This is for illustration purposes only as some uses of motive cells do not require disconnecting and reconnecting a battery cable 202 between the load 154 and the charger 150, but may rely on a charging controller to switch from discharging to a load to charging from a charger using the same battery cable 202 to the battery, e.g., golf carts.

[0050] Motive cells, including deep cycle cells, are used in discharge / recharge cycles whereby the cells power a load, e.g., a forklift or a golf cart, which discharges the cell. After the cells are discharged to a point requiring recharging, or after a predetermined time period, the9178184658Docket No. 074455.00299 cells are recharged. After being charged, and the charging process is terminated, the cells can be returned to service.

[0051] As discussed above, and with further reference to FIG. 1, while there are various charging systems / methods for motive and deep cycle cells, in generally, charging causes the electrolytic decomposition of the water in the electrolyte 20 to oxygen and hydrogen gases 44. The gases 44 bubble up through the electrolyte 20 to the gas space 24 and, in a traditional prior art cell, would normally exit the cell 10 to the surrounding atmosphere 28 through the vent 26 as shown. This causes a loss of water. As discussed previously, routine water maintenance is required to avoid exposing the plates 30, 32 above the electrolyte 20.

[0052] To address the problem of the loss of water from the cell 10, and minimize maintenance costs and potential damage to the cell 10, the present invention provides a means for minimizing the loss of the water from the cell 10, and in some cases eliminate it. This is described initially with further reference to FIG. 2, showing a cell 10 similar to that shown in FIG. 1 and with like elements referenced with like reference numbers. Here, the cell 10 is shown connected to and being charged by the charger 150. Such means for preventing water loss includes a catalyst 48 in fluid communication with the gas space 24 of the cell 10 for recombining the hydrogen and oxygen gases 44 to water vapor 45. Unless otherwise indicated, the phrase “fluid communication” as used herein is intended to mean the uninhibited and unrestricted flow of gases and liquids between two or more objects and / or areas.

[0053] The catalyst 48 is preferably provided or mounted in a recombination device 46 that attaches to the gas vent 26 as further described below. The recombination device 46, in addition to containing the catalyst 48, inhibits the venting of the oxygen and hydrogen gases 44 and water vapor 45 from the cell 10, and also inhibits the ingress of atmospheric gases 28 into the cell 10 through the vent 26. The term “inhibit” as used herein in regard to the venting or ingress of gases means the prevention of the venting and ingress of gases from and into the cell 10 under normal operating conditions. The oxygen and hydrogen gases 44 flow up to the catalyst 48 where they are recombined to water vapor 45, and then the recombined water vapor, and any water vapor from evaporation, is hygroscopically absorbed by the electrolyte 20 in view of the hygroscopic nature of the electrolyte 20, particularly with sulfuric acid electrolyte, which is highly hygroscopic. If water vapor is created at a rate greater than can be hygroscopically absorbed by the electrolyte, then vapor condensation within the condensate device 46 and the cell gas space 24 may occur, which condensate would flow or drip back to the electrolyte 20.

[0054] Hygroscopy is a phenomenon that attracts and absorbs water vapor from the environment surrounding the liquid electrolyte 20 (e.g., the cell gas space 24) directly into the10178184658Docket No. 074455.00299 electrolyte. This restores the water lost to electrolytic decomposition and thereby maintains the volume of the electrolyte 20.

[0055] As mentioned above, the charging of the cell 10 electrolytically decomposes the liquid water in the electrolyte 20 to oxygen and hydrogen gases 44 through the process of electrolysis. The reaction can be shown as H2O(1) — H2(g) + ’ / 202(g). The addition of the recombination device 46 over the vent opening 26 creates a closed system 118 that inhibits the cell gasses 44, 45 from exiting the system 118 and the atmospheric / environment gases 28 from entering the system 118 under normal operating conditions. (The cell container 12, other than the vent opening 26, is leak tight). This closed system 118 includes the electrolyte 20, the gas space 24, and the catalyst 48. Accordingly, within this enclosed system, the decomposed gases 44 are recombined to water vapor 45 by the catalyst 48, which reaction can be shown as H2(g) + ’ / 202(g) — H2O(g), and which water vapor 45 is then hygroscopically absorbed into the electrolyte 20 as shown schematically in FIG. 20, restoring the liquid water that was decomposed. To the extent any water vapor condenses to water within the recombination device 46 or the gas space 24, this water will flow back to the electrolyte 20 and thus remain within the closed system 118 as shown. Within the closed system 118, the electrolyte 20 and the catalyst 48 are in fluid communication with one another so that the gases 44 and water vapor 45 can flow therebetween, i.e., the oxygen and hydrogen gases 44 exiting the electrolyte 20 can flow to the catalyst 48 for recombination to water vapor 45, and the recombined water vapor 45 can flow to the electrolyte 20 for hygroscopic absorption, uninhibited and unrestricted (minimum head loss) as previously noted. Any water vapor that condenses within the closed system 118 will flow back to the electrolyte 20.

[0056] With further reference to FIG. 20, it is believed that the present invention provides an internal recombination / hygroscopic cycle 55 operating within the closed system 118. During the charging of the cell 10, water from the electrolyte 20 is decomposed to oxygen and hydrogen gases 44, and these gases are recombined to water vapor 45 and then returned to the electrolyte 20 through hygroscopic absorption. In motive cells that may have relatively small surface areas 23 of electrolyte, during periods of high gassing rates and thus high vapor generation rates, it is possible that a portion of the water vapor will condense within the recombination device 46 and in the cell gas space 24 if the water vapor is not absorbed hygroscopically sufficiently fast. Should there be any condensation of water vapor within the closed system, this water will flow back to the electrolyte as shown in FIG. 20. Such condensation would take place in addition to the hygroscopic absorption within the closed system 118. In such situations, it is likely that as the cell 10 starts to gas during the charging cycle, the initial water vapor produced is readily handled by hygroscopic absorption, but as the gassing rate increases, it is possible that some11178184658Docket No. 074455.00299 condensation to liquid water will occur, which is returned to the electrolyte 20. It is appreciated that by keeping the hydrogen and oxygen gases, and the water vapor within the closed system 118 with the catalyst and electrolyte 20, neither the gases, water vapor or condensed water escapes the cell 10, thereby minimizing or eliminating the loss of water.

[0057] During very high and unexpected gassing rates, however, it is possible that hydrogen and oxygen gases are generated at a faster rate than can be recombined by the catalyst, and / or the resulting water vapor cannot be absorbed fast enough hygroscopically, causing an increase of the pressure within the cell 10 to a point that the pressure relief valve will release the excess gases and vapor. While this may happen sometimes, under normal operating conditions, the closed system cycle 118 can provide a maintenance free flooded battery cell - one that loses virtually no water over long periods of time, or at least minimize the water loss and delay water maintenance. Further description of this cycle with reference to FIG. 20 is provided below.

[0058] It is appreciated that the embodiment of the invention as so far described is a traditional motive flooded vented cell 10 with the addition of a recombination device 46. Accordingly, as will be understood with the further description below, this initial exemplary embodiment of the present embodiment can be applied to retrofitting exiting prior art flooded motive cells currently in service as well as newly produced traditional flooded motive cells and newly produced motive cells configured to incorporate the devices and methods of the current invention.

[0059] A preferred example of a recombination device 46 in accordance with the present invention is now described with reference to FIG. 2 and with further reference to FIGS. 3, 4, 5, 6 and 7. Again, the battery cell 10 shown in FIG. 2 is identical to that of FIG. 1, but with the addition of a recombination device 46 attached to the cell 10 in the vent opening 26, and the cell 10 shown disconnected from the load 154 and connected to the charger 150. The recombination device 46 houses the catalyst 48 for recombining the hydrogen and oxygen gases 44, inhibits the venting of gases (the oxygen and hydrogen gases 44 and water vapor 45), inhibits the ingress of atmospheric gases 28, and maintains fluid communication between the electrolyte 20, the gas space 24, and the catalyst 48. The recombination device 46, attached to the cell 10, sealingly closes off the interior 43 of the cell (electrolyte 20, gas space 24, etc.) from the atmosphere 28 and creates the closed system 118 within which the continuous cycle 55 takes place (see FIG. 20).

[0060] The recombination device 46 has a housing 50 defining an interior 52 (also referred to herein as an internal area 52) that contains a catalyst device 54 (see FIGS. 4, 5). The housing 50 is preferably cylindrical in shape and has an outer wall 56, an inner wall 57, a cylindrical upper section 58a, a cylindrical lower section 58b having a smaller diameter than the upper12178184658Docket No. 074455.00299 section 58a, and a top cover 60 attached to and forming the top of the recombination device 46. In this preferred embodiment, recombination device 46 attaches to the cell 10 at the vent opening 26 (see FIG. 16). The lower section 58b extends through the vent opening 26 into the gas space 24, and the upper section 58a extends outside and above the cell 10. Ribs 51 can be provided on the outside of the housing 50 for ease of handling. The recombination device 46 provides a leak (gas) tight interior 52 that sealingly connects to the cell 10 to inhibit the various gases 44 and 45 from venting to the atmosphere and the ingress of atmospheric gases 28 into the cell, and which in combination with the cell 10 creates an enclosed internal area 63 that includes the electrolyte 20, cell gas space 24, and the interior 52 of the recombination device 46. The internal recombination / hygroscopic cycle 55 operates within this enclosed internal area 63, which also forms the closed system 118 as seen in FIG. 20. The recombination device 46 is now described in further detail.

[0061] The lower section 58b, also referred to as the mount section, defines a lower internal area 52b, and has an opening 62 in the housing 50, which here is formed as a pair of openings 62 on opposite sides of the housing 50. The opening 62 is sized to allow fluid communication of gases between the device 46 and the gas space 24, and to allow any condensed water to flow back to the cell 10. Internal splash shields 64 along the inside of the housing 50 are spaced from and face each of the openings 62 to protect the catalyst from electrolyte 20 that may splash through the openings 62, such as when the cell 10 is being moved. A mount 68 attaches the recombination device 46 to the vent opening 26. The mount 68 illustrated is a bayonet mount having two arms 68a, which is a common mount used in the U.S. and Europe with cell vent openings. A resilient gasket or O-ring 70, made of a suitable material such as EPDM, works with the mount 68 as known in the art to provide a leak tight connection between the cell 10 and recombination device 46. The lower section 58b of the housing wall includes a solid angled section 66 that directs any liquids within towards the slotted openings 62 for exiting the recombination device 46. A solid bottom section 71 of the housing prevents electrolyte from splashing directly into the recombination device 46. The housing 50 is made of any suitable material such as a flame retardant high-temperature polymer. One exemplary material is XAREC® with a 30% glass impregnated filler.

[0062] The opening 62 is sized and configured to allow fluid communication between the device 46 and the cell gas space 24. This allows oxygen and hydrogen gases 44 generated by the electrolytic decomposition of the water in the electrolyte 20 to flow to the catalyst 48, and water vapor 45 generated by the catalyst 48 to flow to the electrolyte 20 where it is hygroscopically absorbed. The opening 62 (or the multiple openings 62 if more than one) should be positioned above the electrolyte 20, preferably in the gas space 24, to allow13178184658Docket No. 074455.00299 uninhibited and unrestricted flow of oxygen and hydrogen gases to the catalyst 48, and uninhibited and unrestricted flow of the water vapor from the catalyst 48 to the entire surface area 23 of the electrolyte 20, or as much of the surface area 23 as possible. It is believed that the larger the electrolyte surface area 23 in fluid communication with the water vapor from the recombination device 46, the greater the attraction of the water vapor to the electrolyte 20 and thus the greater the rate of absorption into the electrolyte that is possible. As further described below, this flow of gases allows the oxygen and hydrogen gases from the electrolyte 20 to reach the catalyst 48 quickly and easily for recombination to water vapor, and allows the recombined water vapor to quickly and easily be hygroscopically absorbed into the electrolyte 20 at least at the same rate that the water vapor is generated. The opening 62 also facilitates the flow of any water vapor that condenses in the recombination device 46 to the electrolyte 20. In one preferred form, the opening 62, or all of multiple openings 62, should have a total area of at least about .2 square inches, the illustrated embodiment having a combined total opening 62 area of about .3 to .32 square inches.

[0063] The internal area 52b of the lower section 58b opens to the internal area 52a of the upper section 58a in which the cylindrical catalyst device 54, containing the catalyst 48, is housed. This is an exemplary catalyst device 54 for the catalyst 48 and is described in further detail below. This internal area 52a is also referred to herein as the catalyst chamber 52a. Preferably, the opening between the internal areas 52a and 52b should be as large as possible, using as much of the vent opening 26 as possible, or at least sized not to inhibit or restrict the flow of gases 44, 45 between the two sections to permit fluid communication therebetween.

[0064] A support bracket 72 holds the catalyst device 54 in place. It includes a catalyst device support member 73 that includes a cylindrical wall 74 forming a cup like shape having an internal diameter selected to receive and friction fit with the outer wall 76 of the catalyst device 54. The cylindrical wall 74 includes at least one slot 74a to provide sufficient resiliency to hold the catalyst device 54 securely in place, the preferred embodiment having three slots 74a positioned equally distanced from one another around the wall 74. The support bracket 72 further includes three legs 78 that rest on a lower internal shoulder 80 of the device housing 50 where the upper and lower housing sections 58a, 58b meet, and a conical shaped head 82 that allows any water vapor condensate thereon to drain away from the catalyst device 54 and down towards the openings 62. As seen in the figures, the catalyst device 54 is supported in the housing internal area 52 in fluid communication between it and the openings 62. The support bracket 72 can be made of any material suitable for the environment within the catalyst device 54, including a preferred material XAREC® with a 30% glass impregnated filler. One or more support ribs 75 can be provided along the inner wall 57 of the housing lower section 58b to14178184658Docket No. 074455.00299 support the bottom of the catalyst device 54 and prevent it from falling out of catalyst device support member 73.

[0065] Positioned above the support bracket 72 is a cap 84 that sealingly closes the upper end of the internal area 52 of the recombination device 46 to make it leak tight. This prevents gases from the cell 10 from flowing through the recombination device 46 to the atmosphere 28, and thereby inhibits the venting of gases from the cell 10. The cap 84 also prevents any gases from the atmosphere 28 from flowing through the recombination device 46 to the cell. A top shelf 88 having a substantially flat top surface 88a and a substantially flat lower surface 88b separate and close off the internal area 52 of the recombination device 46 from the atmosphere 28. An O-ring 90 is positioned between the outer circular surface of the cap 84 and the inner wall surface 57 of the housing 50 to create the leak tight seal. The O-ring 90 is preferably made of a resilient material suitable for the acidic environment of the cell 10, such as EPDM rubber material. The cap 84 also has legs 92 resting on the support bracket 72 and providing a space 94 between it and the support bracket 72. The cap 84 can be made of any suitable material such as XAREC® with a 30% glass impregnated filler.

[0066] A pressure relief valve 96 protects the cell 10 from over pressurization. Too high of an internal pressure can lead to deformation of the container 12, such as bulging. An under pressure or vacuum relief valve 98 may also be provided to protect the cell 10 from a vacuum. Current vented flooded cells allow uninhibited gas flow in and out of the cell 10 and thus pressure within such cells will be the same as that of the surrounding atmosphere 28, which is 0 psi relative to the surrounding atmosphere (unless otherwise indicated, all pressures provided herein are relative to the surrounding atmosphere 28). Containers 12 of traditional motive flooded cells, made of materials such as polypropylene, can handle more than minor over and under pressurizations as compared with atmospheric pressure, although each battery manufacturer has its own specifications. Accordingly, the pressure relief valve 96 is provided for safety purposes to protect the cell 10 from pressure incidents during unintended cell behavior that could damage the cell 10 or even lead to an explosion in the case of excess gassing. The vacuum relief valve 98 is optional as it is unlikely that a significant vacuum event would damage the container 12 of a motive cell, but again, each manufacturer’s specifications are different, and it is believed that most motive cells would not benefit from a vacuum relief valve.

[0067] Any type of pressure relief valve suitable for use in battery cells can be used, such as those currently used in VRLA cells. One exemplary type of pressure relief valve is illustrated herein. Both relief valves 96 and 98 of the illustrated embodiment are formed of a resilient material that deforms under pressure to allow gases to pass. With specific reference to FIGS. 4, 5 and 7, each relief valve 96, 98 includes a disc shaped head 100, a shaft 102 extending from the15178184658Docket No. 074455.00299 disc shaped head 100 through an opening 104 in the shelf 88, and a shoulder 106 bulging from the shaft 102 to maintain the disc shaped head 100 in place urged against the shelf 88.

[0068] With reference to the pressure relieve valve 96, it is oriented with its disc shaped head 100 on the upper side of the shelf 88 as seen in FIGS. 4, 7, and 16 to cover small openings 108 extending through the shelf 88 (not shown in FIG. 7 as the openings 108 associated with the pressure relief valve 96 are below the head 100, but see the openings 108 for vacuum relief valve 98 in FIG. 7 which are the same), and its shoulder 106 is against the lower side of the shelf 88 as seen in FIGS. 4 and 16. The disc shaped head 100 covers the openings 108 and tapers towards its outer edge to allow sufficient flexibility to deform upwardly and uncover the openings 108 in response to pressure exerted on the underside of the disc shaped head 100 through the openings 108. The vacuum relief valve 98 acts similarly, but is oriented in the opposite configuration as the pressure relief valve 96 opens when a vacuum develops within the cell 10 due to the higher atmospheric pressure acting from above through the openings 108 on the disc shaped head 100 to allow gas from the atmosphere 28 into the cell 10 and relieve the vacuum. The pressure and vacuum relief valves 96 and 98 of the illustrated embodiment are preferably made of a suitable resilient material such as Viton or high temperature silicone, which can be configured for the desired flexibility to activate to open at a pressure selected for the desired use. Such relief valves are known in the art and alternative configurations can be used to provide the desired pressure and vacuum relief.

[0069] The pressure relief valve 96 is configured to activate (open) at a selected pressure, plus or minus some tolerance. This pressure will control the maximum pressure within the cell 10. For the pressure relief valve 96, the pressure selected should be sufficient to inhibit the venting of gases to the atmosphere from the cell 10, but low enough to protect the cell 10 from damage due to over pressurization. It has been found that the pressure needed to inhibit the venting of gases is much lower than that which would damage a typical flooded cell 10. A preferred range of pressure within the cell 10 at which the pressure relief valve 96 will activate is from an amount greater than 0 psi up to and including about 5 psi relative to the atmosphere, with a preferred specific pressure goal of about 3 psi relative to the atmosphere. The pressure selected could go as high as the pressure that a specific cell 10 could handle without damage, although this pressure will depend on the specifications of each cell manufacturer. Again, the goal is not pressurization of the cell 10, but to inhibit venting of the gases from the cell to the atmosphere so that the gases can be recombined to water vapor, while protecting the cell 10 from damage due to over pressurization should such an event occur. In practice, a maximum pressure within the upper range of what is permissible for a given cell may be preferred to help keep the oxygen and hydrogen gases within the cell 10 for recombination, particularly when16178184658Docket No. 074455.00299 there may be higher rates of gassing. It is also believed that the highly hygroscopic electrolyte 20, having a high affinity for the water vapor produced from the recombined gases will, under normal operating conditions within the cell 10, absorb the water vapor at a high enough rate to maintain the cell pressure at a minimum. For vacuum relief protection, if desired or recommended for a particular cell, the vacuum relief valve should open at a negative pressure recommended by the manufacturer. Pressure relief valves 96 and 98 of the type discussed above are known in the art and can be obtained for the desired activation pressure.

[0070] The circular top cover 60 forms the top of the housing 50. It is attached preferably to the main housing section by ultrasonic welding. A disk-shaped flame arrestor 110 (see FIGS. 4, 5 and 6) formed of a micro-porous disc allows gas to pass through, but prevents a flame from passing through as known in the art. The flame arrestor 110 is snap or friction fitted to the bottom of the cover 60 as shown. All gases exiting or entering recombination device 46, when one of the pressure or vacuum relief valves 96, 98 open, will flow through the flame arrestor 110 to prevent any flame outside of the cell 10 from entering the cell. This is a safety feature as oxygen and hydrogen gases are explosive. Any suitable material such as polypropylene can be used. The top cover 60 has a top section 112 with vent openings 114 to complete the housing 50. The cover 60 can be made of a material similar to that of the housing 50, in this case XAREC® with a 30% glass impregnated filler.

[0071] A preferred catalyst device 54 is now described in further detail with reference FIGS. 4, 5 and 8 through 10. The catalyst device 54 includes a catalyst container 119, formed as a cylindrical tube 120, having a micro-porous wall 122 and preferably formed from a hydrophobic material. Positioned within an internal area 124 of the container 119 is the catalyst 48 provided on spheres or beads 126. A filter material 128 can optionally be provided within the container 119 as well. In the illustrated embodiment, it is seen that the catalyst 48 and filter material 128 are not packed tightly within the tube 120, leaving a space 142 within the tube as further discussed below. The tube 120 has openings 129 at both tube ends 130a, 130b closed by plugs 132, These are now described in further detail.

[0072] The tube 120 is preferably cylindrical, having a cylindrical wall 122 made of a micro-porous material such as PTFE (e.g., TEFLON®). Other suitable materials can be used, such as porous ceramic material - e.g., a porous ceramic tube or cup as further described below as another preferred embodiment. The tube 120 is preferably hydrophobic to repel water and electrolyte from entering or closing the micro-pores through the tube wall 122. The tube 120 has a length, wall thickness t and a porosity selected for the desired gas flow rates into the internal area 124 for recombination by the catalyst 48. The combination of wall thickness t and porosity of the tube 110 can be selected to handle the expected gas flow rates passing therethrough. It is17178184658Docket No. 074455.00299 desirable to allow for a sufficient gas flow rate to keep up with the rate of gassing from the water decomposition in the cell 10. Too low of an allowed gas rate through the wall 122 may cause a buildup of gases in the cell 10, with a corresponding increase of internal cell pressure that could cause the loss of gases through the pressure relief valve 96. It is believed preferable to have a thinner wall thickness t with a lower porosity for a desired flow rate as compared to a thicker wall thickness t with a higher porosity seeking the same flow rate. Experience has shown that the thicker wall with a higher porosity is harder to control to obtain the desired flow rates. Preferable wall configurations include a porous PTFE tube length of 1 inch having a wall thickness of 1 / 8 inch, outer diameter of .5 inch, and average pore size of 10-20 micron, suitable to allow gases to pass through while able to quench a hydrogen-oxygen flame. It is further understood that the length of the tube for any give configuration of thickness and porosity can be selected to obtain a desired flow rate of gases into the device 46, with a corresponding change in the amount of catalyst within the tube 120 for recombining the oxygen and hydrogen gases to water vapor. Accordingly, depending on the application, the catalyst tube 120 can be of any length and / or diameter.

[0073] In the illustrated embodiment, the cylindrical tube plugs 132 closing the openings 129 at the ends 130a, 130b are made of a suitable solid material such as a high-temperature polymer suitable for battery environments. One suitable material is XAREC® with a 30% glass impregnated filler. As XAREC® does not readily weld to the PTFE material of the tube 120, a friction fit between the two is preferred. Here, teeth projections 136 are provided on the side wall of the plugs 132. XAREC® is a harder material than PTFE, and as the plugs 132 are pushed into the openings 129 at the tube ends 130a, 130b, the teeth 136 “dig” or penetrate into the softer tube wall 122 to create the friction fit to sealingly close the openings 129.

[0074] The catalyst 48 is arranged within the tube 120. Precious metal catalyst such as powdered palladium and platinum are preferred, provided on a suitable substrate 126 such as the ceramic spheres or beads 126 shown. Any suitable material can be used such as the ceramic silica. For the illustrated catalyst 48 provided on a substrate bead 126, the catalyst 48 is coated onto the substrate bead 126 with a suitable adhesive, or otherwise provided on the surface of the substrate.

[0075] Consideration is to be given to the size of the substrate 126. Ceramic materials such as silica have a higher thermal mass than many other suitable substrate materials, and a larger bead of silica as compared to a smaller bead of silica can absorb, store and release more heat, potentially increasing in temperature sufficiently to damage materials such as PTFE, a preferred material for the tube 120. This is a possibility during a high rate of gassing, particularly where the beads 126 are in contact with the inner wall 140 of the tube 120. To avoid this problem,18178184658Docket No. 074455.00299 smaller ceramic beads 126, e.g., microbeads, are preferred for supporting the catalyst 48. Because of their smaller thermal mass, they will not rise as high in temperature. In one preferred form, the catalyst 48 can be a powdered palladium attached to silica bead substrates within the size range of and including 400 to 600 microns, the palladium being a relatively small percentage by weight of the catalyst / bead unit, e.g., about .3 to 1 percent by weight of the catalyst / bead unit, a more preferred range being from about .3 to .5 percent by weight of the catalyst / bead unit.

[0076] The minimum amount of catalyst 48 provided should be sufficient to recombine the expected rate of gas generated by the decomposition of water under normal cell operating conditions. Too little catalyst that is insufficient to handle the rate of gas decomposition will lead to pressurization of the cell 10 and gas venting, causing a loss of water. In practice, it is preferable to oversize the amount of catalyst rather than undersize. For most applications, an amount of catalyst 48 sufficient to recombine the amount of gas produced by 5 amps of charging current at any given time is preferred.

[0077] Poison filters 128 can be provided within the tube 120 to remove materials from the gases that would prevent the catalyst from working. For example, it is common to add alloys to the lead plates of the cell to improve their strength. One of the most common alloy metals used with motive cells is antimony, which is added to the lead of the positive plate 30 to add strength. During cell operations, however, the antimony can form stibine gas (SbHs) that can negatively affect the catalyst. A preferred poison filter material is potassium hydroxide (KOH) provided on a carbon substrate. In the present embodiment, a poison filter material 128 of KOH is provided on a carbon substrate intermixed with the beads 126 of catalyst 48. In one preferred form, the filter material 128 is an activated carbon produced from carbonaceous source materials such as bamboo, coconut husk, com husk, willow peat, wood, coir, lignite, coal, and petroleum pitch soaked in a solution of KOH. The activated carbon is preferably sized at +12 x 30 mesh or larger. This minimum size avoids the smaller particles and powders that can block gas flow when wet.

[0078] With specific reference to FIGS. 9 and 10, where a filter 128 is provided, it is preferable to provide the catalyst beads 126 and filter material 128 intermixed together. It is also preferable in this embodiment not to tightly pack the filter and catalyst together within the tube 120, but provide the space 142 within to help maintain the filter and catalyst beads in a loose mixed form. As gases can enter the tube 120 through the cylindrical wall from any direction, the intermixing of the catalyst with the filter material helps keep the filter material dry, which filter material can absorb water that condenses from the vapor. The heat generated by the catalyst 48 during the recombination reaction helps keep the filter material dry. Moreover, it is preferable to19178184658Docket No. 074455.00299 provide gas recombination and the resulting heat throughout the internal area 124 of the tube 120 to prevent condensation of the water vapor within it, which again could interfere with the flow of gases through the filter material 128 to the catalyst 48.

[0079] An alternative preferred embodiment of a catalyst device 54 is now described with reference to FIGS. 11 and 12. This embodiment is suitable for use with the same recombination device 46 previously described above.

[0080] In this embodiment, the catalyst device container 119 is formed from a porous ceramic material, such as 99 percent alumina. The porous ceramic alumina is formed in the shape of a can 170 having a porous cylindrical wall 172, a porous closed end 174 formed integrally with the porous cylindrical wall 172, and an open end 176 having an opening 178. The opening 178 is sealed closed by a ceramic putty 144 that bonds to the internal walls 140 of the can 170. About a 1 / 8 inch thick layer of putty 144 is believed to be sufficient. Alternatively, a non-porous plug 132 similar to that discussed above with reference to FIGS. 9 and 10 could be used. Positioned within the internal area 124 of the container 119 is the catalyst 48 provided on spheres or beads 126 and can include filter material 128, both as previously discussed above. The catalyst 48, catalyst beads 126, filter material 128 and configuration of these within the container 119 are similar to that of FIGS. 9 and 10 with like elements being identified with like reference numbers. As a ceramic material may be hydrophilic, such a catalyst device should preferably be shielded or positioned away from the electrolyte 20. See, for example, the above discussion with reference to the splash shields 64 as seen in FIG. 4.

[0081] The can 170 has a length, wall thickness t and a porosity selected for the desired gas flow rates into the internal area 124 for recombination by the catalyst 48. As noted previously, the combination of wall thickness t and porosity of the container 119 material can be selected for the desired gas flow rates into and out of the catalyst device 54. It is desirable to provide for a gas flow rate that at minimum can handle the expected rate of gassing due to the decomposition of water in the cell 10 during normal operation, and preferable to provide for a greater amount of gassing to ensure that the normal and unexpected gassing events can be handled to avoid losing water. The pores of the ceramic walls 172 are preferably no larger than the maximum size required to quench a hydrogen-oxygen flame, i.e., to prevent a flame from passing through. This is believed to be a pore size of about 100 microns in diameter. In practice, however, the pores can be much smaller and still sized to handle the rate of gassing expected and more. Ceramic materials such as silica are stronger than PTFE and therefore can have a smaller wall thickness t, thereby allowing a lower porosity for a desired gas flow rate as compared to PTFE. A preferable configuration for a porous ceramic silica can 170 has a length of about 23 mm, a wall outer diameter of about 11.5 mm, a wall internal diameter of about 7 mm, and average pore20178184658Docket No. 074455.00299 size of about 20 microns. This embodiment also has the additional porous wall area at the closed end 174 through which gases can flow. The closed end 174, preferably oriented to be on the bottom in the recombination device 46 so that the porous end is closer to the electrolyte, would have a similar wall thickness as that of the wall 152, of about 4.5 mm.

[0082] With refence to FIGS. 13, 14 and 15, an alternative embodiment of a recombination device 46 is now described. This embodiment is similar to the prior described embodiment with like elements identified with like reference numbers. As with the device described with reference to FIGS. 3-7, the present recombination device 46 has a cylindrical housing 50 having external ribs 51, a catalyst device 54 supported within, and a cap 84 for sealingly closing the upper end of the internal area 52 to make the recombination device 46 leak (gas) tight. An Ciring 90 is positioned between the outer circular surface of the cap 84 and the inner wall surface 57 of the housing 50 to create the leak tight seal. The cap 84 includes a pressure relief valve 96 and a vacuum relief valve 98 in the same manner as in the previously described embodiment. Positioned above the cap 84 is a circular top cover 60 forming the top of the housing and which includes a flame arrestor 110 as described with the previous embodiment. The catalyst device 54 can be that previously described with refence to FIGS. 8 - 10 or to FIGS. 11 and 12 (which is illustrated in FIG. 15).

[0083] One difference from the prior described recombination device 46 is the opening 62 of the housing 50 that sits inside the gas space 24 of the cell 10. Here the opening 62 comprises two openings on opposing sides of the lower section 58b of the housing, each opening including a series of smaller slotted openings, but which maintains the preferred total opening area as described above for the prior described embodiment. Another difference is the use of two wheel shaped support brackets 160 positioned on opposite ends of the catalyst device 54. The two support brackets 160 are identical in structure but oriented in opposite directions so as to receive an end of the catalyst device 54. The support brackets 160 include an inner cylindrical wall 74 forming a cup like shape having an internal diameter selected to receive an end 130 of the catalyst device 54 within. The inner cylindrical wall 74 can include one or more slots 74a to provide sufficient resiliency for the friction fit. Here, three slots 74a are positioned equally apart from one another around the wall 74 to provide sufficient resiliency where a friction fit is desired. The inner cylindrical wall 74 also includes along its outer edge stop tabs 162 to prevent the catalyst device 54 from moving or falling through the opening defined by the cylindrical wall 74. The support brackets 160 further include an outer rim 164 connected to the inner cylindrical wall by arms 166, and having a diameter to fit within the upper section 58a of the housing 50 and maintain the catalyst device 54 centered within; the outer rim 164 of the lower wheel shaped support bracket 160 rests on a lower internal shoulder 80 (see FIG. 15) within the21178184658Docket No. 074455.00299 housing 50, while the upper wheel shaped support bracket 160 supports the cap 84 thereon. The wheel shaped support brackets 160 can be made of the same material as the support brackets 72 of the prior described embodiment, here XAREC® with a 30% glass impregnated filler.

[0084] Catalyst devices 54 of the type illustrated above provide flexibility for handling cells 10 of different sizes and with different gassing rates. For example, in one alternative, multiple catalyst devices 54 can be added to the recombination device 46 for the expected gassing rates. This would allow production of standard sized catalyst devices 54, e.g., standard length tubes 120 or cans 170 with a standard amount of catalyst within. Such devices 54 can be combined for desired gassing rates. It is also appreciated that the length and the diameter of the tube 120 can be selected for the desired amount of catalyst within. Some alternative configurations for recombination devices 46 using such catalyst devices 54 are illustrated below with reference to the figures.

[0085] With reference to FIG. 17, a recombination device 46 with multiple catalyst devices 54 is shown attached to a cell 10 in the vent opening 26. The recombination device 46 is similar to those described above with reference to FIGS. 3 - 7 and FIGS. 13 - 15, but configured to support multiple catalyst devices 54 therein using similar catalyst device support members 73 as seen in FIGS. 5 and 14. The arrows 148 in the figure represent the water vapor 45 exiting the recombination device 46. This example highlights the use of multiple catalyst devices 54 allowing the handling of higher rates of gassing without creating excessive heat from the recombination reaction that might be created by simply adding a higher density of catalyst to a single catalyst device 54.

[0086] With reference to FIG. 18, a recombination device 46 having a longer catalyst device 54 is illustrated. The recombination device 46 is similar to those described above with reference to FIGS. 3 - 7 and FIGS. 13 - 15, but configured to support a single longer catalyst device 54 therein using a similar catalyst device support member 73 as seen in FIG. 5 or 14. This embodiment can handle higher gassing rates without excessive heat generation due to the recombination reaction.

[0087] With reference to FIG. 19, a recombination device 46 is shown having a simpler configuration while still using any of the catalyst devices 54 described above. As seen, this recombination device 46 has a uniform diameter creating a simpler configuration within providing less chance for water vapor to condense and remain within the recombination device 46.

[0088] FIG. 19 also shows the use of insulation 180 that can be provided for use in colder environments to help retain the heat generated by the recombination reaction to minimize condensation and maintain the efficiency of the recombination process. In the illustrated22178184658Docket No. 074455.00299 embodiment, the insulation 180 is provided in the form of an insulated cap having an opening 182 through which any gases can be exchanged between the atmosphere and the recombination device 54 should the pressure or vacuum relief valves ever activate. The insulation preferably is be made of any suitable material such as a high temperature non-flammable polymer, and which can be the same material as that of the catalyst device housing. Insulation 180 is not limited to the recombination device 46 of FIG. 19 and can be provided with any such device. It also need not be a separate component but can comprise a housing material for the recombination device that has heat transfer properties selected for maintaining the desired temperature within the device 46.

[0089] The hygroscopic absorption of the water vapor by the electrolyte 20 is believed to be temperature independent at typical operating environments of flooded motive cells. Nevertheless, for those operating environments sufficiently cold to potentially have a negative effect on the operation of the recombination device, insulation 180 can be provided as discussed above.

[0090] Cell Operation. An example of the operation of a cell 10 in accordance with the present invention is now discussed with reference to FIG. 16. The cell 10 of FIG. 16 is similar to that of FIG. 2, although only partially shown, with like elements being identified with like reference numbers. The recombination device 46 is the same as that shown in FIGS. 3 to 10, again with like elements being identified with like reference numbers.

[0091] The cell 10 in FIG. 16 is a discharged flooded motive cell shown being recharged after its use in service, e.g., a forklift used at a warehouse for many hours. The battery cable 202 was disconnected from the load (see Fig. 2), again, e.g., the forklift, and reconnected to the charger 150 via couplings 210 and 206. During the charging cycle, the cell 10 receives electrical power via the battery cable 202 to the plates 30, 32, to recharge the cell. Regardless of the charging method used, at some point during the charging cycle, the charge voltage will rise to a level to cause the electrolytic decomposition of water in the electrolyte 20 to oxygen and hydrogen gases 44 as shown by bubbles (44). The gases 44 float up through the electrolyte 20 to the gas space 24, where the gases are in fluid communication with the catalyst 48 in the recombination device 46, allowing the exchange of gases therebetween. From the gas space 24, the gases 44 flow upwardly (arrows 146) into the recombination device 46 through the openings 62, and ultimately through the pores 61 in the wall of the catalyst container 119 of the catalyst device 54 where the catalyst recombines the oxygen and hydrogen gases 44 to water vapor 45. With the catalyst device 54 in fluid communication with the electrolyte 20, the water vapor 45 flows out of the tube 120 through the pores 61 (see FIG. 8), down through the recombination device 46 and through the opening 62 into the gas space 24 (arrows 148), where it contacts the23178184658Docket No. 074455.00299 electrolyte 20. The electrolyte 20, e.g., sulfuric acid, being highly hygroscopic, attracts and absorbs the water vapor into the liquid electrolyte 20. Based on the amount of the electrolyte surface area available for hygroscopic absorption and the rate of gassing and recombination to water vapor, it is possible that a portion of the water vapor will condense within the recombination device 46, which water 149 would flow back through the recombination device 46 through opening 62 to the electrolyte 20.

[0092] Should there be an over pressurization of the cell 10 beyond a predetermined safe limit, the pressure relief valve 96 would open to relieve the pressure, the gases from within the cell 10 passing through the flame arrestor 110 and out the openings 114 (see FIG. 5). Although a vacuum relief valve is generally not required, an optional vacuum relief valve 98 is shown in FIG. 16 . Should there be an unexpected event causing a vacuum within the cell 10 beyond a predetermined safe limit, the vacuum relief valve 98 would open to relieve the vacuum, allowing atmospheric gases 28 to enter. Such events are unexpected and rare in the life of most cells, but relief valves are provided for safety should such events happen.

[0093] It is preferable to provide sufficient catalyst 48 to handle expected rates of gassing (rate of the electrolytic decomposition of the water to oxygen and hydrogen gases 44) in a flooded cell 10 when charging. Under normal operating conditions with expected rates of gassing, the internal recombination / hygroscopic cycle 55 as seen in FIG. 20 will reach a dynamic equilibrium between the rate of gassing (creation of the oxygen and hydrogen gases 44), the rate of recombination of the oxygen and hydrogen gases 44 to water vapor 45, and the rate of hygroscopic absorption of the water vapor 45 into the electrolyte 20. Put another way, the internal recombination / hygroscopic cycle 55 will reach a point where the rate of recombination of oxygen and hydrogen gases 44 to water vapor 45 is essentially the same as the rate of decomposition of the water in the electrolyte to oxygen hydrogen gases 44 by electrolysis, which will be essentially the same as the rate of hygroscopic absorption of the water vapor 45 into the electrolyte. If the gassing rate changes, for example should the gassing rate change due to a temporary change in the charging voltage, after a short period of time, a new dynamic equilibrium will be reached between the rate of decomposition, the rate of recombination, and the rate of hygroscopic absorption. In some applications, in addition to the hygroscopic absorption, where the gassing and vapor recombination rates are greater than what is being absorbed hygroscopically, particularly in cells that have smaller surface areas of electrolyte, some water vapor may condense to water on the internal walls of the recombination device 46 and / or on the walls of the cell container 12 defining the gas space 24, and returned to the electrolyte by dripping and / or water flow, but nevertheless maintaining the dynamic24178184658Docket No. 074455.00299 equilibrium. With condensation, the cycle could be referred to as the recombination / hygroscopic / condensation cycle.

[0094] The hygroscopy phenomenon for restoring water vapor 45 to the electrolyte 20 is advantageous as compared to other means, such as condensation of the water vapor, which is highly temperature dependent and followed by a flow of liquid water from the recombination device 46 back to the electrolyte 20. Hygroscopy within the cell 10 provides an efficient and fast acting process to return the water to the electrolyte, is less temperature dependent, and one that is believed to be less likely to lose gases and water vapor from the cell 10, such as through excess gassing and over pressurization that would cause the loss of gases through pressure relief venting and thus a loss of water from the cell. Accordingly, it is preferable to maximize the amount of water vapor 45 that is returned to the electrolyte 20 by hygroscopy by configuring the recombination device 46 to return a majority of the water vapor through hygroscopic absorption, i.e., at least 50% of the water vapor, and preferably up to 100% of the water vapor or as close to 100% as possible, the remainder by condensation, to obtain the full benefits.

[0095] In practice, the full benefits of the present invention can be achieved by ensuring that the recombination / hygroscopic cycle reaches a dynamic equilibrium as quickly as possible, even after changes in the gassing rate, and that 100% of the water vapor or as close to 100% as possible is hygroscopically absorbed by the electrolyte. This will provide a maintenance free battery cell 10 in terms of no measurable water loss over long periods of time, creating, in essence, a maintenance free flooded battery cell. Some condensation of water vapor is acceptable and should not prevent the restoration of most if not all of the water lost through decomposition, as well as any evaporation of water that may have taken place.

[0096] Certain factors should be considered to reach these benefits. First, a sufficient amount of catalyst 48 should be provided to handle the highest gassing rate expected for the operating conditions of the cell 10. Some oversizing of the amount of catalyst 48 may be desirable to handle unexpected events of gassing above the expected rates. Again, the oxygen and hydrogen gases 44 should be recombined as fast as they are produced to avoid a buildup of the gases within the cell. To enable the catalyst 48 to recombine the oxygen and hydrogen gases at least at the rate that the gases are produced, the catalyst device 54 should be configured to allow the oxygen and hydrogen gases to pass into the device 54 to the catalyst 48 within without restriction, and to allow the water vapor produced therein to exit the catalyst device 54 without restriction.

[0097] Quick and unrestricted flow of the cell gases 44 from the cell gas space 24 to the catalyst 48, and of the water vapor 45 from the catalyst 48 to the surface 23 of the electrolyte 20 should be provided. This helps to minimize condensation and quickly reach a dynamic25178184658Docket No. 074455.00299 equilibrium for the recombination / hygroscopic cycle 55 as soon as possible. One consideration here is to configure the interior 52 (also referred to as the internal area) of the recombination device 46 to provide for such uninhibited (unrestricted) gas flow. The opening 62, or the combined multiple openings 62, should be sized to allow the fluid communication through it in both directions, i.e., oxygen and hydrogen gases flowing from the gas space 24 to the catalyst device 54 for recombination to water vapor 45, and the water vapor flowing from the catalyst device back to the electrolyte 20 for hygroscopic absorption. The faster this process takes place, the less likely water vapor will remain or have time to condense in the recombination device 46, and the more likely that the electrolyte 20 will hygroscopically absorb the water vapor. Preferred opening 62 sizes were described previously.

[0098] Another consideration for quick and unrestricted flow of the gases is the volume of the interior 52 of the recombination device 46 (that volume sealed from the atmosphere 28). The smaller the volume, at least in the upper interior 52a, the less area in the recombination device 46 for the gases 44 and water vapor 45 to build up and lag within, leading to quicker recombination and quicker hygroscopic absorption with less chances for condensation of the water vapor. Furthermore, less volume typically means less internal surface area on which the water vapor could condense and interfere with the hygroscopic process. A preferred volume within the interior 52 of the illustrated recombination devices 46 is about 2 cubic inches or less; the volume within the upper interior 52a of the illustrated recombination devices being about 1.5 cubic inches or less, and the volume of the lower interior 52b being about .48 cubic inches.

[0099] Another factor for quick and unrestricted flow of the gases is the placement of the catalyst device 54. Preferably, it should be as close to the gas space 24 and the electrolyte surface 23 as reasonably possible, considering that the catalyst 48 should be protected from the electrolyte 20, which could block the pores 61 through which gases and water vapor flow. This can be achieved as shown in the illustrated embodiments, the catalyst device 54 being positioned in the recombination device 46 at an elevation just above the vent opening 26 and near the openings 62, and protected by the splash shield 64.[000100] In addition to novel apparatuses and devices, the present invention also provides novel methods as now described with further reference to FIG. 20. Attaching the recombination device 46 to the vent opening 26 of a conventional flooded cell 10 as seen in FIG. 16 sealingly closes off the cell gas space 24 from the atmosphere 28, thereby inhibiting any gas flow between the cell 10 and the atmosphere 28 during normal operation of the cell 10. It is seen that for such a motive flooded cell 10 being charged, the invention provides in one form an internal recombination / hygroscopic cycle of a) gas generation (electrolysis of water to oxygen and hydrogen gases), b) catalytic recombination of the oxygen and hydrogen gases to water vapor,26178184658Docket No. 074455.00299 and c) hygroscopic absorption of the water vapor by the electrolyte 20. This method is carried out within the closed system 118 created by the addition of the recombination device 46 attached to the vent opening 26, and which includes within the closed system 118 the electrolyte 20, the gas space 24, the internal area 52 of the recombination device (that area sealed off from the atmosphere and which includes the catalyst device 54 with the catalyst 48 within). The method can further include d) providing fluid communication between the electrolyte 20 and the catalyst 48, which all takes place within the closed system 118. By recombining the oxygen and hydrogen gases generated within the cell to water vapor, and absorbing the water vapor back into the electrolyte 20, the electrolyte level 22 can be maintained without the need to add additional water. Under normal operating conditions, this cycle can provide a maintenance free flooded motive battery cell that loses little or virtually no water over long periods of time, and possibly over the lifetime of the cell 10.[000101] As another embodiment, it is seen that for such a motive flooded cell 10 being charged, the invention provides an internal recombination / hygroscopic / condensation cycle of a) gas generation (electrolysis of water to oxygen and hydrogen gases), b) catalytic recombination of the oxygen and hydrogen gases to water vapor, c) hygroscopic absorption of a portion of the water vapor by the electrolyte 20, and d) condensation of another portion of the water vapor, which then flows back to the electrolyte 20. This method is also carried out within the closed system 118 created by the addition of the recombination device 46 attached to the vent opening 26, and which includes within the closed system 118 the electrolyte 20, the gas space 24, the internal area 52 of the recombination device (that area sealed off from the atmosphere and which includes the catalyst device 54 with the catalyst 48 within). The method can further include e) providing fluid communication between the electrolyte 20 and the catalyst 48, which all takes place within the closed system 118.[000102] Methods of the present invention are also applicable to retrofitting existing vented flooded cells. Here the methods as set forth immediately above would include the step of attaching or providing a recombination device in accordance with the present invention, such as the recombination devices 46 illustrated above, in the vent opening 26 of a traditional prior art motive cell, including such cells already in service. Here, a cell 10 that was previously vented while in service can be retrofitted with the recombination device 46 in the vent opening, which is simple to do for most cells, to begin to operate in accordance with the present invention and obtain the full benefits thereof.[000103] Whether providing a new cell 10 in accordance with the present invention or retrofitting a conventional prior art cell, the methods of the present invention can take various forms. For example, in another form, a method of the present invention provides: a) charging a27178184658Docket No. 074455.00299 cell at a charge voltage having a value that is in excess of the value of the open circuit voltage of the cell or, in another form, providing a charging voltage high enough to be capable of causing electrolytic decomposition of the water in the electrolyte; b) electrolytic decomposition of the water in the electrolyte to oxygen and hydrogen gases; c) catalytic recombination of the oxygen and hydrogen gases to water vapor; and d) hygroscopic absorption of the water vapor by the electrolyte 20. As noted above, this can further include e) condensation of some of the water vapor, which then flows back to the electrolyte 20.[000104] Another embodiment of the method where a cell is charged at a charge voltage that has a value in excess of the value of the open-circuit voltage of the cell such that there is electrolytic decomposition of water in the electrolyte to hydrogen and oxygen gases would include: a) inhibiting the venting of gases from the flooded cell, the gases including the hydrogen and oxygen gases from decomposition of water in the electrolyte and the water vapor generated by recombining the hydrogen and oxygen gases; b) catalytically recombining the oxygen and hydrogen gases to water vapor by use of a catalyst; c) providing fluid communication between the electrolyte and the catalyst by which the hydrogen and oxygen gases and the catalytically recombined water vapor can flow between the electrolyte and the catalyst; and d) hygroscopically absorbing a majority of said water vapor into the electrolyte. This method can further include step e) continuing steps a through d as long as there is electrolytic decomposition of water in the electrolyte to hydrogen and oxygen gases. Step (a) above can further include the inhibiting of the ingress of gases from the atmosphere into the cell, and can be carried out by adding, e.g., a recombination device 46 in accordance with the present invention.[000105] In view of the forgoing, the present solution concerns implementing systems and methods for charging a flooded cell used in motive service whereby the cell is repeatedly discharged and recharged (a continuous discharge / recharge cycle). The cell is discharged when providing power to a load. After the discharging, the cell is recharged by receiving electrical current from a charger until fully charged at which time the recharging is terminated. Thereafter, the cell is ready to discharge to the load again to repeat the discharge / recharge cycle. The cell includes a positive electrode and a negative electrode in a spaced relationship from one another. During charging of the cell, a charging voltage of the cell exceeds the value of the open-circuit voltage of the fully charged cell causing electrolytic decomposition of the water in the electrolyte to hydrogen and oxygen gases. The methods comprise: a) providing the positive electrode and the negative electrode fully immersed in a hydroscopic material of the liquid electrolyte; b) inhibiting the venting of gases from the cell, said gases including the hydrogen and oxygen gases; c) catalytically recombining the oxygen and hydrogen gases to water vapor28178184658Docket No. 074455.00299 by use of a catalyst; d) providing fluid communication between said electrolyte and said catalyst by which said hydrogen and oxygen gases and said catalytically recombined water vapor can flow between said electrolyte and said catalyst; e) allowing unrestricted flow of said water vapor to the electrolyte to provide a dynamic equilibrium for a hygroscopic cycle; and f) hygroscopically absorbing at least a portion of said water vapor directly into the electrolyte from an internal atmosphere of the flooded cell.[000106] It is appreciated that the present invention provides methods for minimizing the loss of water from motive battery cells, and even creating a water maintenance free flooded cell that requires little if any water over long periods of time. The present invention also provided devices and sub combinations of devices for carrying the inventive method. The present invention also provides for the retrofitting or modification of flooded motive cells that are currently in use to eliminate most if not all of the watering maintenance. The present invention also provides for the construction of new cells in accordance with the invention.[000107] It is understood that the above identified arrangements are merely illustrative of the many possible specific embodiments which represent applications of the present invention. Numerous and varied other arrangements can readily be device in accordance with the principles of the invention without departing from the spirit and scope of the invention.178184658

Claims

Docket No. 074455.00299CLAIMSWhat is claimed is:

1. A method for charging a flooded cell used in motive service whereby the cell is repeatedly discharged and recharged (a continuous discharge / recharge cycle), the cell being discharged when providing power to a load, and then after the discharging, said cell being recharged by receiving electrical current from a charger until fully charged at which time the recharging is terminated and thereafter the cell is ready to discharge to the load again to repeat the discharge / recharge cycle, wherein said cell includes a positive electrode and a negative electrode in a spaced relationship from one another, and a liquid electrolyte that includes water in which the positive electrode and the negative electrode are immersed, and wherein, during charging of the cell, a charging voltage of the cell exceeds the value of the open-circuit voltage of the fully charged cell causing electrolytic decomposition of the water in the electrolyte to hydrogen and oxygen gases, said method comprising: a) inhibiting the venting of gases from the cell, said gases including the hydrogen and oxygen gases; b) catalytically recombining the oxygen and hydrogen gases to water vapor by use of a catalyst; c) providing fluid communication between said electrolyte and said catalyst by which said hydrogen and oxygen gases and said catalytically recombined water vapor can flow between said electrolyte and said catalyst; and d) hygroscopically absorbing at least a portion of said water vapor into the electrolyte.

2. A method according to claim 1, wherein said charging comprises a topping charge which includes a voltage value in excess of the value of the open-circuit voltage of the cell when fully charged, and during said topping charge electrolytic decomposition of the water in the electrolyte to hydrogen and oxygen gases takes place.

3. A method according to any one of claims 1 to 2, wherein step (d) comprises hygroscopically absorbing at least 10% of said water vapor into the electrolyte.

4. A method according to any one of claims 1 to 2, wherein step (d) comprises hygroscopically absorbing at least 20% of said water vapor into the electrolyte.30178184658Docket No. 074455.002995. A method according to any one of claims 1 to 4, wherein step (c) comprises providing fluid communication between the catalyst and at least 98% of a surface area of the electrolyte.

6. A method according to any one of claims 1 to 5, wherein said cell is a flooded lead-acid cell having an electrolyte comprising sulfuric acid.

7. A method according to any one of claims 1 to 6, wherein step (a) further includes inhibiting the ingress of gases from the environment into the cell.

8. A method according to any one of claims 1 to 7, wherein another portion of said water vapor produced in step (b) condenses to water, which water flows into the electrolyte.

9. In a method for recharging a flooded lead-acid cell used in motive service whereby the cell is repeatedly discharged and recharged, the recharging taking place after the discharging ceases and includes a charge voltage that has a value that is in excess of the value of the opencircuit voltage of the fully charged cell, said recharging terminating once the cell is fully charged, said cell including, in spaced relationship, a positive electrode and a negative electrode, and a liquid electrolyte comprising a hygroscopic material in which the positive electrode and the negative electrode are immersed, wherein, during said charging of the cell, there is a loss of water from the electrolyte through electrolytic decomposition of the water creating hydrogen and oxygen gases that vent from the cell to the surrounding atmosphere, the improvement comprising minimizing the loss of water from the cell by inhibiting the venting from the cell of the hydrogen and oxygen gases, catalytically converting the oxygen and hydrogen gases to water vapor, providing fluid communication between said catalyst and said electrolyte by which said hydrogen and oxygen gases can flow to said catalyst and said catalytically converted water vapor can flow to said electrolyte.

10. The method of claim 9, further including the step of hygroscopically absorbing at least a portion of said catalytically converted water vapor into the electrolyte.

11. The method of claim 10, further including the step of condensing another portion of the water vapor to liquid water, which liquid water flows back to the electrolyte.

12. The method according to any one of claims 1 - 11, wherein the method is carried out by a recombination device comprising a housing, a catalyst disposed within said housing, a mount for sealingly attaching said recombination device to said cell, and which device is configured to provide for the fluid communication of the oxygen and hydrogen gases and the water vapor31178184658Docket No. 074455.00299 between said catalyst and said electrolyte within said battery cell, and to inhibit the venting of the oxygen and hydrogen gases and the water vapor to the atmosphere.

13. The method according to claim 12, wherein said recombination device includes a pressure relief valve configured to vent gases from the cell to the atmosphere at a pressure greater than 0 psi relative to atmospheric pressure.

14. The method according to claim 12, wherein said recombination device includes a pressure relief valve configured to vent gases from the cell to the atmosphere at a pressure greater than 1 psi relative to atmospheric pressure.

15. The method according to claim 12, wherein said recombination device includes a pressure relief valve configured to vent gases from the cell to the atmosphere at a pressure greater than 2 psi relative to atmospheric pressure.

16. The method according to claim 12, wherein said recombination device includes a pressure relief valve configured to vent gases from the cell to the atmosphere at a pressure greater than 2 psi and up to and including 5 psi relative to atmospheric pressure.

17. The method according to claims 1 to 16, wherein said method further includes condensing a portion of said catalytically converted water vapor, which condensate flows into the electrolyte.

18. The method according to any one of claims 1 to 17, further comprising that after said cell is fully charged, providing an equalization charge having a voltage greater than 2.6 volts per cell to intentionally decompose water in the electrolyte to hydrogen and oxygen gases, and which gases are recombined to water vapor by said catalyst.

19. A catalyst device for combining oxygen and hydrogen gases to water vapor within a flooded storage battery cell used in motive service whereby the cell is repeatedly discharged and recharged; comprising: a container having a porous wall defining an internal area, said porous wall having pores sized to allow oxygen and hydrogen gases and water vapor to pass therethrough; a catalyst arranged within said internal area, said catalyst capable of reacting oxygen gas and hydrogen gas to form water vapor; and a substrate on which said catalyst is attached.32178184658Docket No. 074455.0029920. The device according to claim 19, wherein said container includes at least one opening closed by a plug disposed within said opening.

21. The device according to claim 20, wherein said porous wall has an inner surface, and said plug comprises a member having a projection disposed to friction fit against said inner surface.

22. The device according to claim 21, wherein said projection comprises teeth like projections.

23. The device according to claim 19, wherein said container comprises at least one opening closed by a ceramic putty.

24. The device according to any one of claims 19 to 23, wherein said porous wall comprises PTFE.

25. The device according to any one of claims 19 to 24, wherein said porous wall comprises a porous ceramic of silica.

26. The device according to any one of claims 19 to 25, further comprising a filter arranged within said internal area, said filter capable of filtering out stibine.

27. The device according to claim 26, wherein said filter is intermixed with said catalyst within said internal area.

28. The device according to any one of claims 19 to 27, wherein said catalyst is disposed on a substrate comprising silica.

29. The device according to claim 28, wherein said substrate comprises beads.

30. The device according to any one of claims 19 - 28, wherein said catalyst is provided on a substrate comprising a hydrophilic material.

31. The device according to any one of claims 19 - 28, wherein said catalyst is provided on a substrate comprising a hydrophobic material.

32. A recombination device attachable to a flooded battery cell having a liquid electrolyte comprising a hygroscopic material, a gas space, and a vent opening through which gases can vent from the cell, the device comprising: a housing providing a leak tight interior when the device is attached to said cell;33178184658Docket No. 074455.00299 a catalyst disposed within said leak tight interior, said catalyst capable of combining oxygen and hydrogen gases to form water vapor; a mount for sealingly attaching the device to the vent opening of the battery cell; and said housing having an opening positioned to be in fluid communication with the gas space of the cell through the vent opening when the device is attached to the cell to allow fluid communication between the catalyst and the electrolyte.

33. The recombination device according to claim 32, further comprising a pressure relief valve.

34. The recombination device according to any one of claims 32 to 33, wherein said opening is positioned to be above the surface of the electrolyte when said device is attached to said vent opening to provide fluid communication between the water vapor within said recombination device and the surface of the electrolyte within the cell.

35. The recombination device according to any one of claims 32 to 34, wherein said interior has a volume no greater than about 2 cubic inches.

36. The recombination device according to any one of claims 32 to 35, wherein said opening of said housing is at least about .2 inches square.

37. The recombination device according to any one of claims 32 to 35, wherein said opening of said housing is at least about .3 inches square.

38. The recombination device according to any one of claims 32 to 37, wherein said interior of said housing is configured to allow unrestricted flow of water vapor from said catalyst to said electrolyte so that a majority of said water vapor generated by said catalyst is hygroscopically absorbed by said electrolyte.

39. The recombination device according to any one of claims 32 to 38, wherein said catalyst comprises a catalyst device in accordance with any one of claims 19 to 31.

40. An improved flooded motive battery cell, comprising: a container having a vent opening therein; a liquid electrolyte comprising a hygroscopic material within said container; a gas space in which oxygen and hydrogen gases generated by electrolysis of water from within the cell collects, said vent opening being in fluid communication with said gas space; at least one positive plate immersed in said electrolyte;34178184658Docket No. 074455.00299 at least one negative plate immersed in said electrolyte; and a recombination device in accordance with any one of claims 31 to 39 sealingly connected to said vent opening to be in fluid communication with said gas space.

41. An improved flooded motive battery cell in accordance with claim 40, further comprising a pressure relief valve configured to release gas from said gas space to an atmosphere outside of said cell at a predetermined pressure above 2 psi relative to atmospheric pressure.

42. An improved flooded motive battery cell in accordance with claim 40, further comprising a pressure relief valve configured to release gas from said gas space to an atmosphere outside of said cell at a predetermined pressure of at least about 3 psi relative to atmospheric pressure.

43. An improved flooded motive battery cell in accordance with any of claims 40 to 42, wherein said positive plate comprises at least 3 percent antimony.

44. A method of operating a flooded electrolyte battery cell used in motive service to prevent the loss of water, the method comprising: a) discharging the cell by providing power to a load; b) terminating step (a); c) charging the cell at a charge voltage having a value sufficiently high to electrolytically decompose water in a liquid electrolyte to oxygen and hydrogen gases, said liquid electrolyte including a hygroscopic material; d) catalytically recombining the oxygen and hydrogen gases to water vapor by use of a catalyst; e) inhibiting venting of said oxygen and hydrogen gases and said water vapor from the cell; f) providing fluid communication between the catalyst and the electrolyte for the oxygen and hydrogen gases and water vapor; g) hygroscopically absorbing a majority of the water vapor of step (d) into the electrolyte; and h) terminating said charging after said cell is fully charged.

45. A method according to claim 44, wherein step (g) further comprises the step of condensing a portion of said water vapor not absorbed hygroscopically to liquid water, and returning said liquid water to said electrolyte.35178184658Docket No. 074455.0029946. A method according to claim 44 or 45, wherein step (d) is carried out by use of a catalyst configured to recombine the oxygen and hydrogen gases to water vapor that is returned to the electrolyte in step g) at a rate at least that of the rate of decomposition of the water in step (c).

47. The method according to any one of claims 44 to 46, wherein steps (d) through (f) are carried out by the device of claim 32.

48. The method according to any one of claims 44 to 47, wherein step (g) comprises hygroscopically absorbing at least 90 percent of the water vapor of step (d) into the electrolyte.

49. The method according to any one of claims 44 to 47, wherein step (g) comprises hygroscopically absorbing at least 95 percent of the water vapor of step (d) into the electrolyte.

50. The method according to any one of claims 44 to 47, wherein step (g) comprises hygroscopically absorbing at least 98 percent of the water vapor of step (d) into the electrolyte.

51. The method according to any one of claims 44 to 47, wherein step (g) comprises hygroscopically absorbing about 100 percent of the water vapor of step (d) into the electrolyte.

52. The method according to any one of claims 44 to 47, wherein step (g) comprises hygroscopically absorbing at least 50 percent of the water vapor of step (d) into the electrolyte, and the remainder of the water vapor condenses to liquid water.

53. The method according to any one of claims 44 to 52, wherein the fluid communication between said electrolyte and said catalyst is configured so that during steps c through g a state of dynamic equilibrium is reached between the rate of oxygen and hydrogen gases created by the electrolytic decomposition of water and the rate of water vapor hygroscopically absorbed in step (g).

54. The method according to any one of claims 45 to 52, wherein the fluid communication between said electrolyte and said catalyst is configured so that during steps (c) through g a state of dynamic equilibrium is reached between the rate of oxygen and hydrogen gases created by the electrolytic decomposition of water and the rate of water vapor and condensate returned to the electrolyte in step (g).

55. The method according to any one of claims 45 to 54, further comprising:36178184658Docket No. 074455.00299 during step (c), reaching a state of dynamic equilibrium between the rate of water vapor produced in step (d) and the rate of water vapor returned to the electrolyte in step (g) hygroscopically and by condensate flowing to the electrolyte.

56. The method according to any one of claims 44 to 55, wherein said method is carried out with the battery cell of claim 40.

57. In a method for charging a flooded motive cell that includes a charge voltage that causes electrolytic decomposition of water, said cell including, in spaced relationship, a positive electrode and a negative electrode, a liquid electrolyte comprising a hygroscopic material in which the positive electrode and the negative electrode are immersed, and a gas space in fluid communication with said electrolyte, wherein, during said charging of the cell, there is a loss of water from the electrolyte through the electrolytic decomposition of the water creating hydrogen and oxygen gases that freely vent from the cell to the surrounding atmosphere, the improvement comprising minimizing the loss of water from the cell by: providing a closed system that inhibits the exchange of any gases and liquids between the closed system and the environment outside the closed system, said closed system including within it the electrolyte and gas space within the cell; catalytically converting the oxygen and hydrogen gases to water vapor within said closed system by use of a catalyst disposed within said closed system; and hygroscopically absorbing at least a portion of the water vapor into the electrolyte within said closed system.

58. The method of claim 57, wherein said electrolyte and said catalyst are in fluid communication one another.

59. The method of claim 58, wherein the fluid communication between said electrolyte and said catalyst is configured so that a dynamic equilibrium is reached between the rate of oxygen and hydrogen gases generated through electrolytic decomposition and the rate of water vapor returned to the electrolyte.

60. The method of any one of claims 57 to 59, wherein said cell is a lead acid cell and said electrolyte comprises sulfuric acid.

61. The method of any one of claims 57 to 59, wherein said cell is a Nickel / Cadmium cell and said electrolyte comprises potassium hydroxide.

62. The method of any one of claims 57 to 59, wherein said cell is a Nickel / Metal Hydride cell and said electrolyte comprises potassium hydroxide.37178184658Docket No. 074455.0029963. The method according to any one of claims 57 to 62, wherein at least 95% of the oxygen and hydrogen gases are hygroscopically absorbed into the electrolyte.

64. The method according to any one of claims 57 to 62, wherein at least 98% of the oxygen and hydrogen gases are hygroscopically absorbed into the electrolyte.

65. The method according to any one of claims 57 to 64, wherein said step of providing a closed system comprises attaching a recombination device in accordance with claim 32 to a vent opening of said cell.

66. An improved flooded motive battery cell, comprising: a container having a cell opening therein; a liquid electrolyte within said container and comprising a hygroscopic material; a gas space in which oxygen and hydrogen gases generated by electrolysis of water from within the cell collects, the cell opening being in fluid communication with the gas space; at least one positive plate immersed in the electrolyte; at least one negative plate immersed in the electrolyte; and a recombination device sealingly closing said cell opening to form a leak tight connection therewith, said device comprising: a housing having a leak tight interior; a catalyst disposed within said leak tight interior, said catalyst capable of combining oxygen and hydrogen gases to form water vapor; and said housing having an opening positioned to be in fluid communication with the gas space of the cell through the cell opening to allow fluid communication between the catalyst and the electrolyte.

67. The cell of claim 66, wherein said leak tight interior has a volume no greater than about 2 cubic inches.

68. The cell of claims 66 or 67, wherein said opening of said housing of said recombination device is at least about .2 inches square.

69. The cell of any one of claims 66 to 68, wherein said opening of said housing of said recombination device is at least about .3 inches square.

70. The cell according to any one of claims 66 to 69, wherein said positive plate comprises lead alloyed with at least 3 percent antimony.38178184658Docket No. 074455.0029971. The cell according to any one of claims 66 to 70, wherein said cell is configured for more than 1000 charge cycles.

72. A method according to any one of claims 1 to 2, wherein step (d) comprises hygroscopically absorbing at least 25% of said water vapor into the electrolyte.

73. A method according to any one of claims 1 to 2, wherein step (d) comprises hygroscopically absorbing at least 50% of said water vapor into the electrolyte.

74. A method according to any one of claims 1 to 2, wherein step (d) comprises hygroscopically absorbing at least 75% of said water vapor into the electrolyte.

75. The cell according to anyone of claims 66 to 71, wherein said cell is configured to discharge up to at least 70%.

76. The cell according to anyone of claims 66 to 71, wherein said cell is configured to discharge up to at least 80%.39178184658

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