Abstract:
A liquid reserve battery including: a collapsible storage unit having a liquid electrolyte stored therein; a battery cell having an inlet in communication with an outlet of the collapsible storage unit, the battery cell having gaps dispersed therein; a first pyrotechnic material disposed adjacent the collapsible storage unit such that initiation of the first pyrotechnic material provides pressure to collapse the collapsible storage unit to heat and force the liquid electrolyte through the outlet and into the gaps; and one or more heat exchangers disposed between the outlet of the collapsible storage unit and the inlet of the battery cell.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation-in-part of U.S. application Ser. No. 13/350,907, filed on Jan. 16, 2012, the entire contents of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates generally to reserve power sources for munitions; and more particularly to liquid reserve batteries for use in gun-fired munitions, sub-munitions, mortars and the like. 
         [0004]    2. Prior Art 
         [0005]    Reserve batteries of the electrochemical type are well known in the art for a variety of uses where storage time before use is extremely long. Reserve batteries are in use in applications such as batteries for gun-fired munitions including guided and smart, mortars, fusing mines, missiles, and many other military and commercial applications. The electrochemical reserve-type batteries can in general be divided into two different basic types. 
         [0006]    The first type includes the so-called thermal batteries, which are to operate at high temperatures. Unlike liquid reserve batteries, in thermal batteries the electrolyte is already in the cells and therefore does not require a release and distribution mechanism such as spinning. The electrolyte is dry, solid and non-conductive, thereby leaving the battery in a non-operational and inert condition. These batteries incorporate pyrotechnic heat sources to melt the electrolyte just prior to use in order to make them electrically conductive and thereby making the battery active. The most common internal pyrotechnic is a blend of Fe and KClO 4 . Thermal batteries utilize a molten salt to serve as the electrolyte upon activation. The electrolytes are usually mixtures of alkali-halide salts and are used with the Li(Si)/FeS 2  or Li(Si)/CoS 2  couples. Some batteries also employ anodes of Li(Al) in place of the Li(Si) anodes. Insulation and internal heat sinks are used to maintain the electrolyte in its molten and conductive condition during the time of use. 
         [0007]    The second type includes the so-called liquid reserve batteries in which the electrodes are fully assembled for cooperation, but the liquid electrolyte is held in reserve in a separate container until the batteries are desired to be activated. In these types of batteries, since there is no consumption of the electrodes under these circumstances, the shelf life of the batteries is essentially unlimited. The battery is activated by transferring the electrolyte from its container to the battery electrode compartment (hereinafter referred to as the “battery cell”). 
         [0008]    A typical liquid reserve battery is kept inert during storage by keeping the aqueous electrolyte separate in a glass or metal ampoule or in a separate compartment inside the battery case. The electrolyte compartment may also be separated from the electrode compartment by a membrane or the like. Prior to use, the battery is activated by breaking the ampoule or puncturing the membrane allowing the electrolyte to flood the electrodes. The breaking of the ampoule or the puncturing of the membrane is achieved either mechanically using certain mechanisms or by the high-G firing setback shock. In these batteries, the projectile spin or a wicking action of the separator is generally used to transport the electrolyte into the battery cells. 
         [0009]    In recent years, there have been a number of advancements in reserve battery technologies. Among these advances are superhydrophobic nanostructured materials, bimodal lithium reserve battery, and ceramic fiber separator for thermal batteries. In one liquid reserve battery technology under development, “superhydrophobic nanostructured material” is used in a honeycomb structure to keep the electrolyte separated from the battery cell. “Electrowetting” is achieved by the application of a trigger voltage pulse. The electrolyte can then penetrate the honey comb structure and come into contact with the electrodes, thereby making the cell electrochemically active. 
         [0010]    The currently available liquid reserve batteries of all types and designs and those that are known to be under development materials suffer from several basic shortcomings for munitions applications, including the following:
       1. The main shortcoming of currently available liquid reserve batteries of all types and designs is their very poor performance at low temperatures, usually below −25 deg. F. and for becoming almost non-functional at lower temperatures. In most munitions applications, however, the batteries are required to be operational at significantly lower temperatures of −40 deg. F. and sometimes lower, and sometimes after storage at temperatures as low as −65 deg. F.   2. The second shortcoming of liquid reserve batteries is their relatively slow rise time, particularly at low temperatures. Researchers have, however, attempted to minimize this shortcoming by, for example, by injecting pressurized electrolyte into the battery cells; using wicks to increase the electrolyte diffusion rate; utilize spin and/or setback to move electrolyte into the battery cell to increase; etc. These methods have improved the liquid reserve battery rise time, but have not resolved the problems at low temperatures.       
 
       SUMMARY 
       [0013]    A need therefore exists for liquid reserve batteries that can effectively operate with good performance at low temperatures, particularly at temperatures below −25 to −40 deg. F. and even after being stored at temperatures as low as −65 deg. F. 
         [0014]    A need also exists for liquid reserve batteries that do not only operate effectively operate with good performance at low temperatures, but are also capable of becoming operational very rapidly following activation, i.e., to have a so-called short rise time to full or near full capacity. 
         [0015]    In particular, there is a need for such liquid reserve batteries for gun-fired munitions, mortars and the like that are inactive prior to launch and become active during or after certain amount of time following launch or other similar linear or rotary (spin) acceleration or deceleration event. Such liquid reserve batteries must be capable of withstanding high firing accelerations; have very long shelf life, preferably beyond 20 years; and that can be used in munitions with any spin rates, including very low or no spin to very high spin rate munitions. 
         [0016]    In particular, there is a need for relatively small reserve power sources for munitions, particularly for smaller caliber munitions, that can withstand very high firing accelerations; have very long shelf life, preferably beyond 20 years; and that can be in munitions with very high spin rates. 
         [0017]    Such liquid reserve power sources are preferably initiated as a result of the munitions firing using inertial igniters such as those disclosed in U.S. Pat. Nos. 7,437,995; 7,587,979; 7,587,980; 7,832,335 and 8,061,271 and U.S. patent application Ser. Nos. 12/774,324; 12/794,763; 12/835,709; 13/180,469; 13/207,280 and 61/551,405 (the full disclosure of each of which being incorporated herein by reference) or piezoelectric-based inertial igniters such as those disclosed in U.S. Pat. No. 8,024,469 and U.S. patent application Ser. Nos. 13/186,456 and 13/207,355 the full disclosure of each of which being incorporated herein by reference) or other electrical initiators. The piezoelectric-based inertial igniters, particularly those that can provide relatively long initiation delay, are highly advantageous since by delaying the initiation, the time period in which the battery is subjected to high acceleration/deceleration levels is reduced or even preferably eliminated. The reserve battery may also be activated following launch when its power is needed, which may in certain cases be long after launch and even landing. The initiation devices to be used must also be capable to operate safely by differentiating all-fire and various no-fire events such as accidental drops and vibration and impact during transportation and loading and even nearby explosions. The task of differentiating all-fire conditions from no-fire conditions is preferably performed without the use of external acceleration sensors and the like, and/or the use of external power sources. 
         [0018]    An objective of the present invention is to provide new types of liquid reserve batteries (power sources) that can operate efficiently at very low temperatures and that can be activated and brought to operational power levels rapidly. Such liquid reserve batteries can also be fabricated in small sizes suitable for use in small and medium caliber munitions, sub-munitions and the like. 
         [0019]    Another objective of the of the present invention is to provide new types of liquid reserve batteries and methods of their design and construction such that they could be activated by the initiation of pyrotechnic materials, thereby allowing their liquid electrolyte to be heated prior and even after injection into the battery cell to allow activation at very low temperatures and faster activation. 
         [0020]    Another objective of the present invention is to provide new types of liquid reserve batteries and methods of their design and construction such that they could be activated by the initiation of pyrotechnic materials, and the pressure generated by the initiation of the pyrotechnic material be used to rapidly inject the (heated) liquid electrolyte into the battery cell cavities to achieve very fast battery activation. 
         [0021]    In one disclosed liquid reserve battery design, the aforementioned pressure generated by the initiation of the pyrotechnic material is used to generate vacuum in a region of the battery to assist evacuation of the gasses filling the battery cell cavities as the electrolyte liquid enters to fill these cavities, thereby minimizing their resistance to inflow of the liquid electrolyte, further reducing the battery rise time. The provided vacuum (suction) is particularly effective when the liquid electrolyte is being injected into the battery cell cavities under pressure. 
         [0022]    To ensure safety and reliability, the liquid reserve power source withstand and not initiate during acceleration events which may occur during manufacture, assembly, handling, transport, accidental drops, etc. Additionally, once under the influence of an acceleration profile particular to the firing of the ordinance, i.e., an all-fire condition (with or without a programmed delay period), the reserve battery must initiate with high reliability. 
         [0023]    The disclosed reserve power sources are preferably provided with hermetically sealed packaging. The disclosed reserve power sources would therefore be capable of readily satisfying most munitions requirement of 20-year shelf life requirement and operation over the military temperature range of −65 to 165 degrees F., while withstanding high G firing accelerations. 
         [0024]    In many applications, the liquid reserve battery is required to provide full or close to full power very short time after initiation. This capability is particularly challenging when the reserve battery is at very low temperatures such as the aforementioned −65 degrees F. For this reason, the electrolyte must be at a relatively high temperature before it is injected into the battery cell since it is also required to provide the required amount of heat to rapidly heat the cell elements while staying warm enough to ensure proper operation of the reserve power source. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    These and other features, aspects, and advantages of the apparatus of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where: 
           [0026]      FIG. 1  illustrates a sectional schematic of the first embodiment of the pyrotechnic activated liquid reserve battery for fast activation and high low-temperature performance. 
           [0027]      FIG. 2  illustrates a sectional schematic of a first variation of the pyrotechnic activated liquid reserve battery of  FIG. 1 . 
           [0028]      FIG. 3  illustrates a sectional schematic of a second variation of the pyrotechnic activated liquid reserve battery of  FIG. 1 . 
           [0029]      FIG. 4  illustrates a sectional schematic of a variation of the pyrotechnic activated liquid reserve battery of  FIG. 3 . 
           [0030]      FIG. 5  illustrates sectional schematic of a third variation of the pyrotechnic activated liquid reserve battery of  FIG. 1 . 
           [0031]      FIG. 6  illustrates a sectional schematic of a fourth variation of the pyrotechnic activated liquid reserve battery of  FIG. 1  with electrolyte liquid heated in a heat-exchanger element prior to injection into the battery cell. 
           [0032]      FIGS. 7A and 7B  illustrate cross-sectional and base views, respectively, of an example of the design of the liquid electrolyte storage unit with its integral heat exchanger component of the liquid reserve battery embodiment of  FIG. 6 . 
           [0033]      FIG. 8A  illustrates the construction of a liquid electrolyte storage unit with integral heat exchanger constructed with formed and seam welded elements for low cost manufacture. 
           [0034]      FIG. 8B  illustrates the formed components used in the construction of the liquid electrolyte storage unit with integral heat exchanger of  FIG. 8A . 
           [0035]      FIG. 9  illustrates a sectional schematic of a fifth variation of the pyrotechnic activated liquid reserve battery of  FIG. 1  with battery cell heated internally by the burning of heat generating pyrotechnic materials. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    An embodiment  10  of the present novel pyrotechnic charge activated liquid reserve batteries is shown in the cross-sectional schematic of  FIG. 1 . The novel pyrotechnic charge activated liquid reserve battery, hereinafter also referred to as simply “liquid reserve battery” consists of a body  11 , which is divided into two compartments  12  and  13 . The compartment  12  is where the liquid electrolyte and pyrotechnic material are located. The compartment  13  is where the battery electrodes are spaced with gaps to accommodate the battery liquid electrolyte, the entire combined volume of which is indicated by the numeral  15  and hereinafter will be referred to as a “battery cell”. The compartments  12  and  13  can be divided by a single relatively rigid separating plate  14 . The battery body  11 , the dividing plate  14  and other structures of the battery can be made out of relatively non-corrosive metal such as stainless steel. The liquid reserve battery  10  terminals are indicated by numeral  16 . The terminals  16  of the liquid reserve battery  10  may be located at any convenient location, such as being positioned on a surface of the battery cell compartment  13  to avoid running wires to them through compartment  12 . 
         [0037]    In general, the body  11  and the compartments  12  and  13  of the liquid reserve battery  10  may be formed to have any convenient shape, such as to match an available space in the munitions. 
         [0038]    In the compartment  12  is located at least one collapsible (e.g., bellow like) storage unit  17  within which the liquid electrolyte  18  is stored. At least one, which can be several, outlet holes  19  are provided on the relatively rigid separating plate  14 . The outlet holes  19  are sealed by relatively thin, such as metallic, diaphragms  20 . Pyrotechnic materials  21 , such as in a layer configuration as shown in the schematic of  FIG. 1  are provided in the sealed volume  22  between the collapsible liquid electrolyte storage unit  17  and the compartment  12  walls. The liquid reserve battery  10  is also provided with an initiation device  23  for igniting the pyrotechnic materials  21 . The initiation device  23  is either of inertial, electrical, or other available types appropriate for the application at hand (e.g., see those listed above) which can, for example, ignite the pyrotechnic material upon the occurrence of an acceleration with at least a predetermined duration and magnitude. 
         [0039]    The liquid reserve battery  10  is activated by the initiation device  23  igniting the pyrotechnic materials  21 . The burning pyrotechnic material  21  generates heat and heats the stored liquid electrolyte  18 . The burning pyrotechnic material  21  also generates pressure within the sealed volume  22  by heating the enclosed gasses as well as by generating new gasses. The generated pressure would then act over the surface of the at least one collapsible liquid electrolyte storage unit  17 , forcing it to collapse, thereby forcing the pressurized liquid electrolyte  18  to rupture the diaphragm(s)  20  separating it from the battery cell  15  and rapidly injecting the heated liquid electrolyte  18  into the cavities between the battery cell  15  electrodes as shown by the arrows  24 . The liquid reserve battery  10  is thereby activated very rapidly without the need for wicks or munitions spin or other additional means. In addition, the heating of the liquid electrolyte  18  (even if it is turned solid due to extreme cold temperatures) would allow activation of the liquid reserve battery  10  at very cold temperatures and ensures its high performance. The heating of the liquid electrolyte  18  would also enhance its diffusion rate inside the battery cell  15 . 
         [0040]    The collapsible liquid electrolyte storage unit  17  can be configured with a relatively large surface area to allow for rapid transfer of heat to the liquid electrolyte  18 . The liquid electrolyte storage unit  17  can also be configured to deform plastically under the generated pressure so that once the pressure has subsided, only a minimal amount of the liquid electrolyte  18  is returned back to the storage unit  17 . Alternatively, particularly when the size of the battery allows, one-way valves (not shown) may be used to prevent the return of the liquid electrolyte  18  back to the liquid electrolyte storage unit  17 . Such fluid one-way valves are well known in the art, such as the use of sealing flaps or balls positioned in an orifice. 
         [0041]    As indicated previously, the burning of the provided pyrotechnic material  21  serves the following purposes. Firstly, it is used for battery activation, i.e., to release the stored liquid battery electrolyte  18  into the battery core  15 . Secondly, it generates heat, which is used to heat the liquid electrolyte  18  to allow the battery to function at very low temperatures and at the same time enhance its penetration rate into the battery cell  15  as well as its rate of diffusion. Thirdly, the pressure generated by the initiation of the pyrotechnic material  21  is used to inject the liquid electrolyte  18  into the battery cell  15  under pressure. Fourthly, as is shown in a later embodiment, the pressure generated by the initiation of the pyrotechnic material  18  can also be used to generate vacuum to assist outflow of gasses occupying the voids inside the battery cell  15  between the electrodes that are to be filled with the liquid electrolyte  18 , thereby minimizing resistance to the inflow of the liquid electrolyte  18  into the battery cell  15 . 
         [0042]    The time that it takes for a liquid reserve battery to become fully active following the activation of the initiation device  23 , also called the battery “rise time” is dependent on the time that it takes for the liquid electrolyte  18  to fill the battery cell  15  cavities and begin to interact with the battery electrodes. The following two alternative embodiments are modifications to embodiment  10  of the present pyrotechnic activated liquid reserve batteries to achieve significantly faster rise time. 
         [0043]    A first modification to the embodiment  10  of  FIG. 1  is illustrated schematically in the cross-sectional view of  FIG. 2  and is indicated as the embodiment  30 . In the embodiment  30 , the distance that the liquid electrolyte has to penetrate inside the battery cell is significantly reduced. This is accomplished as shown in  FIG. 2  by significantly reducing the height of the battery cell compartment  31  (in the indicated vertical direction— 44 ), while distributing the battery core electrodes over a significantly larger surface area of the battery cell compartment (e.g., in a direction orthogonal to the vertical direction). To shorten the path of liquid electrolyte travel within the battery cell  42 , it is also required that the liquid electrolyte be released over as large a surface of the battery cell  42  as possible. To this end, a number of collapsible liquid electrolyte storage units  32  are distributed over the plate separating the liquid electrolyte and pyrotechnic material compartment  33 . 
         [0044]    The battery compartment  31  is still where the battery electrodes are spaced with gaps to accommodate the battery liquid electrolyte. The compartments  31  and  33  can be divided similarly by a single relatively rigid separating plate  34 . The liquid reserve battery body  35 , the dividing plate  34  and other structures of the battery can be made out of relatively non-corrosive metal such as stainless steel. The liquid reserve battery  30  terminals are indicated by numeral  36 . The terminals  36  of the liquid reserve battery  30  may be located at any convenient location, such as being positioned on a surface of the battery cell compartment  31  to avoid running wires to the electrodes  36  through the compartment  33 . 
         [0045]    In general, the body  35  and the compartments  31  and  33  of the liquid reserve battery  30  may be formed into any convenient shape, such as to match the available space in the munitions. 
         [0046]    In the compartment  33  are located a plurality of collapsible (e.g., bellow like) storage units  32  within which the liquid electrolyte  37  are stored. The collapsible storage units  32  are preferably relatively small but numerous, and can be uniformly distributed over the surface of the dividing plate  34  or non-uniformly distributed depending on the corresponding shape/volume of the compartment  31 . The collapsible storage units  32  must obviously contain enough liquid electrolytes  37  to flood the entire battery cell  42  cavities. Each collapsible storage unit  32  is provided with at least one outlet hole  38  in the dividing plated  34 . The outlet holes  38  are sealed by relatively thin, such as metallic, diaphragms similar to the embodiment  10  of  FIG. 1  (not shown). Pyrotechnic materials  39 , preferably in a layer configuration as shown in the schematic of  FIG. 2  are provided in the sealed volume  40  between the collapsible liquid electrolyte storage units  32  and the compartment  33  walls. As discussed above with regard to the bellows, the pyrotechnic materials  39  can be uniformly distributed in the compartment  33  or non-uniformly depending on the distribution of the corresponding collapsible storage units  32  and/or corresponding shape/volume of the compartment  31 . The liquid reserve battery  30  is also similarly provided with an initiation device  41  for igniting the pyrotechnic materials  39 . The initiation device  41  is either of inertial, electrical, or other available types appropriate for the application at hand (such as those listed above). 
         [0047]    The liquid reserve battery  30  is activated by the initiation device  41  igniting the pyrotechnic materials  39 . The burning pyrotechnic material  39  generates heat, which heats the stored liquid electrolyte  37  in all the collapsible storage units  32 . The burning pyrotechnic material  39  also generates pressure within the sealed volume  40  by heating the enclosed gasses as well as by generating new gasses. The generated pressure would then act over the surfaces of all the collapsible liquid electrolyte storage units  32 , forcing them to collapse, thereby forcing the pressurized and heated liquid electrolytes  37  to rupture the diaphragms separating them from the battery cell  42  and rapidly injecting the heated liquid electrolytes  37  into the cavities between the battery cell  42  electrodes as shown by the arrows  43 . The liquid reserve battery  30  is thereby activated very rapidly without the need for wicks or munitions spin or other additional means. In addition, the heating of the liquid electrolyte  37  (even if it is turned solid due to extreme cold temperatures) would allow activation of the liquid reserve battery  30  at very cold temperatures and ensures its high performance. The heating of the liquid electrolyte  37  would also enhance its diffusion rate inside the battery cell  42 . 
         [0048]    The collapsible liquid electrolyte storage units  32  can be configured with a relatively large surface area to allow for rapid transfer of heat to the liquid electrolytes  37 . The liquid electrolyte storage units  32  can also be configured to deform plastically under the generated pressure so that once the pressure has subsided, only a minimal amount of the liquid electrolyte  37  is returned back to the storage unit  32 . Alternatively, particularly when the size of the battery allows, one-way valves (not shown) may be used to prevent the return of the liquid electrolyte  37  back to the liquid electrolyte storage unit  32 . Such fluid one-way valves are well known in the art. 
         [0049]    As indicated previously, the burning of the provided pyrotechnic material  21  serves the following purposes. Firstly, it is used for battery activation, i.e., to release the stored liquid battery electrolyte  37  into the battery cell  42 . Secondly, it generates heat, which is used to heat the liquid electrolyte  37  to allow the battery to function at very low temperatures and at the same time enhance its penetration rate into the battery cell  42  as well as its rate of diffusion. Thirdly, the pressure generated by the initiation of the pyrotechnic material  39  is used to inject the liquid electrolyte  37  into the battery cell  42  under pressure. Fourthly, as it is shown in the next embodiment of the present invention, the pressure generated by the initiation of the pyrotechnic material  39  can also be used to generate vacuum to assist outflow of gasses occupying the voids inside the battery cell  42  between the electrodes that are to be filled with the liquid electrolyte  18 , thereby minimizing resistance to the inflow of the liquid electrolyte  37  into the battery cell  42 . 
         [0050]    It will be appreciated by those skilled in the art that the rise time of the present pyrotechnic activated liquid reserve battery embodiments  10  and  30  of  FIGS. 1 and 2 , respectively, is dependent on the length of the path of travel of the liquid electrolyte inside the battery cell. In the embodiment  30  of  FIG. 2 , the electrodes in the battery cell  42  are considered to be positioned and spaced essentially in the vertical direction, thereby resulting in the void spaces to be filled with the liquid electrolytes to be essentially directed in the vertical direction. As a result, the maximum length of the path that the liquid electrolyte  37  that is injected into the battery cell  42  has to travel becomes essentially the height  44  of the battery cell compartment  31 . This is the case since a considerable number of collapsible liquid electrolyte storage units  32  are considered to be distributed over the entire surface of the dividing plate  34 . As a result, the pressurized and heated liquid electrolyte  37  has to travel a very short distance  44  to fill the cavities between the battery cell  42  electrodes, thereby the liquid reserve battery  30  can be activated very rapidly. 
         [0051]    It is thereby shown that for the same volume of the battery cell, i.e., essentially for the same amount of stored electrochemical energy in a liquid reserve battery, by reducing the depth of the battery cell while increasing its electrolyte facing surface area, as described above and shown in the embodiment of  FIG. 2 , the rise time of the liquid reserve battery is significantly decreased. In the embodiment  30 , by distributing many collapsible liquid electrolyte storage units  32  over the dividing plate  34 , the liquid electrolyte flooded surface area of the battery cell  42  is increased while the depth of the ( 44  in  FIG. 2 ) of the battery cell  42 , i.e., the distance that the liquid electrolyte inflow has to travel, is decreased. In addition, the total surface area of the collapsible liquid electrolyte storage units  32  is also increased, thereby allowing more heat to be transferred to the liquid electrolyte  37  following pyrotechnic material initiation and while being injected into the battery cell  42  cavities. Thus, the heated liquid electrolyte is injected into the battery cell  42  over a significantly larger area and has to travel significantly shorter paths to engulf the battery cell electrodes. As a result, the activation or rise time of the reserve battery is significantly reduced. 
         [0052]    The second modification to the embodiment  10  of  FIG. 1  is illustrated schematically in the cross-sectional view of  FIG. 3  and is indicated as the embodiment  50 . It is noted that in the embodiments of  FIGS. 1 and 2 , the gasses filling up the battery cell cavities would provide certain amount of resistance to the inflow of the injected liquid electrolyte. This resistance can be minimized by providing certain level of relative vacuum (suction) ahead of the path of the liquid electrolyte exit. In the embodiment  50 , the relative vacuum is generated by providing elastic and compressively preloaded (vacuum generating) elements such as bellow type elements  51  shown in the schematic of  FIG. 3 . The preloaded elements  51  (hereinafter referred to as “vacuum generating elements”) are positioned in the liquid electrolyte and pyrotechnic material compartment  56 . The preloaded vacuum generating elements  51  provide enclosed volumes  52  that are sealed with opening (not shown) only to the battery cell compartment  54  on the dividing member (plate)  55 . The preloaded elements  51  can be fabricated with relatively heat resistant materials, such as stainless steel. The vacuum generating preloaded elements  51  may be bellow type or have any other appropriate shape such that that they could be preloaded elastically to significantly reduce their enclosing volume ( 52  in the elements  51 ) so that once they are released from their preloaded configuration; the enclosed volume is significantly increased. The preloaded elements  51  are held in their preloaded configuration shown in  FIG. 3  by pyrotechnic material releasing elements  57  such as burnable fibers. Such elements  57  may also be covered with a pyrotechnic material. 
         [0053]    The embodiment  50  of  FIG. 3  is otherwise similar to the embodiment  30  of  FIG. 2  and also operated similarly. The battery cell compartment  54  is relatively shallow, i.e., the depth of the battery cell compartment  58  is relatively small, thereby making the surface area of the battery cell electrodes  53  relatively large for a given volume of battery cell compartment  54  and reducing the length of the path that the injected liquid electrolyte has to travel inside the voids within the battery cell electrodes  53  to engulf the electrodes. A number of relatively small collapsible liquid electrolyte storage units  59  are distributed over the plate  55  separating the liquid electrolyte and pyrotechnic material compartment  56  from the battery cell compartment  58 . 
         [0054]    The battery compartment  54  is still where the battery electrodes are spaced with gaps to accommodate the battery liquid electrolyte. The liquid reserve battery body  60 , the dividing plate  55  and other structures of the battery can be made out of relatively non-corrosive metal such as stainless steel. The liquid reserve battery  50  terminals are indicated by the numeral  61 . The terminals  61  of the liquid reserve battery  50  may be located at any convenient location, such as being positioned on a surface of the battery cell compartment  54  to avoid running wires through the compartment  56 . 
         [0055]    In general, the body  60  and the compartments  54  and  56  of the liquid reserve battery  50  may have any convenient shape, preferably to match the available space in the munitions. 
         [0056]    The collapsible storage units  59  can be relatively small but numerous, and can be uniformly distributed over the surface of the dividing plate  55 . The collapsible storage units  59  must obviously contain enough liquid electrolytes  62  to flood the entire battery cell  53  cavities. Each collapsible storage unit  59  is provided with at least one outlet hole  63  in the dividing plated  55 . The outlet holes  63  are sealed by relatively thin, such as metallic, diaphragms similar to the embodiment  10  of  FIG. 1  (not shown in  FIG. 3 ). Pyrotechnic materials  64 , such as in a layer configuration as shown in the schematic of  FIG. 3  are provided in the sealed volume  65  between the collapsible liquid electrolyte storage units  59  and the vacuum generating preloaded elements  51  and the compartment  54  walls. The liquid reserve battery  50  is also similarly provided with an initiation device  66  for igniting the pyrotechnic materials  64 . The initiation device  66  is either of inertial, electrical, or other available types appropriate for the application at hand. 
         [0057]    The liquid reserve battery  50  is activated by the initiation device  66  igniting the pyrotechnic materials  64 . The burning pyrotechnic material  64  generates heat, which heats the stored liquid electrolyte  62  in all the collapsible storage units  59 . The burning pyrotechnic material  64  also generates pressure within the sealed volume  65  by heating the enclosed gasses as well as by generating new gasses. The generated pressure would then act over the surfaces of all the collapsible liquid electrolyte storage units  59 , forcing them to collapse, thereby forcing the pressurized and heated liquid electrolytes  62  to rupture the diaphragms separating them from the battery cell  53  and rapidly inject the heated liquid electrolytes  62  into the cavities between the battery cell  53  electrodes as shown by the arrows  67 . 
         [0058]    However, upon ignition of the battery pyrotechnic materials  64 , the releasing elements  57  are released, such as by being burned, thereby releasing the preloaded vacuum generating elements  51 . The preloaded vacuum generating elements  51  would then expand (shown with dotted line and indicated by the numeral  67  in  FIG. 3 ) and generate a relative vacuum within their enclosed spaces  52 , which are connected to the battery cell gas exit passage openings in the dividing plate  55  (not shown but similar to the openings  63 —with or without rupturing thin diaphragms), thereby allowing the gasses within the battery cell  53  cavities that are being filled with the injected liquid electrolytes  62  to be sucked out into the expanding vacuum generating elements  51 . The generated vacuum will then assist the inflow of the liquid electrolyte into the battery cell cavities. As a result, the reserve battery activation or rise time is further reduced. 
         [0059]    The liquid reserve battery  50  is thereby activated very rapidly without the need for wicks or munitions spin or other additional means. In addition, the heating of the liquid electrolyte  62  (even if it is turned solid due to extreme cold temperatures) would allow activation of the liquid reserve battery  50  at very cold temperatures and ensures its high performance. The heating of the liquid electrolyte  62  would also enhance its diffusion rate inside the battery cell  53 . 
         [0060]    In the embodiment  50  shown schematically in  FIG. 3 , the releasing elements  57  are “fibers” that are brought into tension to keep the vacuum generating elements  51  in their preloaded state shown in  FIG. 3 . The initiation of the pyrotechnic materials  64  will then cause the elements  57  to burn, thereby releasing the preloaded vacuum generating elements  51 . 
         [0061]    The collapsible liquid electrolyte storage units  59  can be configured with a relatively large surface area to allow for rapid transfer of heat to the liquid electrolytes  62 . The liquid electrolyte storage units  59  can also be configured to deform plastically under the generated pressure so that once the pressure has subsided, a minimal amount of the liquid electrolyte  62  is returned back to the storage units  59 . Alternatively, particularly when the size of the battery allows, one-way valves (not shown) may be used to prevent the return of the liquid electrolyte  62  back to the liquid electrolyte storage unit  59 . Such fluid one-way valves are well known in the art. 
         [0062]    As indicated previously, in the embodiment  50  shown in the schematic of  FIG. 3 , the burning of the provided pyrotechnic material  64  will serve the following purposes. Firstly, it is used for battery activation, i.e., to release the stored liquid battery electrolyte  62  into the battery cell  53 . Secondly, it generates heat, which is used to heat the liquid electrolyte  62  to allow the battery to function at very low temperatures and at the same time enhance its penetration rate into the battery cell  53  as well as its rate of diffusion. Thirdly, the pressure generated by the initiation of the pyrotechnic material  64  is used to inject the liquid electrolyte  62  into the battery cell  53  under pressure. Fourthly, the pressure generated by the initiation of the pyrotechnic material  64  is used to generate vacuum in the vacuum generating elements  51  to assist outflow of gasses occupying the voids inside the battery cell  53  between the electrodes that are to be filled with the liquid electrolyte  62 , thereby minimizing resistance to the inflow of the liquid electrolyte  62  into the battery cell  53 . 
         [0063]    It will be appreciated by those skilled in the art that similar to the embodiments  10  and  30  of  FIGS. 1 and 2 , respectively, the rise time of these liquid reserve batteries is dependent on the length of the path of travel of the liquid electrolyte inside the battery cell. In the embodiment  50  of  FIG. 3 , the electrodes in the battery cell  53  are also considered to be positioned and spaced essentially in the vertical direction, thereby resulting in the void spaces to be filled with the liquid electrolytes to be essentially directed in the vertical direction. As a result, the maximum length of the path that the liquid electrolyte  62  that is injected into the battery cell  53  has to travel becomes essentially the height  58  of the battery cell compartment  54 . This is the case since a considerable number of collapsible liquid electrolyte storage units  59  are considered to be distributed over the entire surface of the dividing plate  55 . As a result, the pressurized and heated liquid electrolyte  62  has to travel a very short distance  58  to fill the cavities between the battery cell  53  electrodes while being assisted by the vacuum (suction) generated by the released vacuum generating elements  51 , thereby the liquid reserve battery  50  can be activated even faster, i.e., have a faster rise time, than a similar embodiment  30  of  FIG. 2 . 
         [0064]    In the embodiment  50 , the releasing elements  57  of the vacuum generating elements  51  were indicated to be “fibers” that are brought into tension to keep the vacuum generating elements  51  in their preloaded state shown in  FIG. 3 . The initiation of the pyrotechnic materials  64  will then cause the elements  57  to burn, thereby releasing the preloaded vacuum generating elements  51 . It will be, however, appreciated by those skilled in the art that numerous other methods and designs also exists that use heat to release a mechanism, for example shape memory alloys or bimetal based mechanisms, etc., and that any one of these methods may be used in the construction of the disclosed embodiment of the present invention. Furthermore, other means may be used to release the vacuum generated elements that do not utilize heat, such as mechanisms that activate upon a firing acceleration of the munition. 
         [0065]    The vacuum generating elements  51  are released in the shortest possible time by using the pyrotechnic material itself to keep the vacuum generating elements  51  in its preloaded configuration. An example of such an embodiment  70  is shown in the schematic of  FIG. 4 . In the schematic of  FIG. 4 , all elements of the liquid reserve battery are the same as the embodiment  50  of  FIG. 3 , except for the vacuum generating elements  51  releasing elements  57 , which are replaced by the pyrotechnic material “block”  68 , which is positioned between the top surface of the vacuum generating elements  51  and the top surface  69  of the liquid electrolyte compartment  56 . The pyrotechnic material used in the construction of the pyrotechnic block  68  must be strong enough to withstand the preloading force and may be constructed with adequate type and amount of binding agents and/or be provided with reinforcing fibers which are preferably easy to burn such as cotton fibers. 
         [0066]    It will be appreciated by those skilled in the art that in all the above disclosed embodiments, the burning pyrotechnic materials will not only heat the liquid electrolyte before it is injected into the battery cell, but it would also transfer heat to the battery cell compartment afterwards. As a result, the activated liquid reserve battery is kept warm in a cold environment and can operate properly longer in environments with temperatures that are below the temperatures at which it can operate efficiently or is close or below its deactivation temperatures. 
         [0067]    In certain applications, the liquid reserve battery is required to operate for a significant amount of time in temperatures that are below the effective operational temperature of the liquid reserve batteries, usually below 25 degrees F. In such cases, even though in the above embodiments illustrated schematically in  FIGS. 1-4  the pyrotechnic materials initially heats the battery electrolyte before injecting it into the battery cell to activate the battery, in a very cold environment, the battery and its liquid electrolyte will cool down over time and eventually become deactivated when the liquid electrolyte temperature drops below the deactivation temperature or is at temperatures that are too cold for the liquid reserve battery to operate efficiently, i.e., at fill or required power. In such cases, one or more of the following modifications can be made to the design of each one of the above embodiments. 
         [0068]    The embodiment  80  shown schematically in the cross-section view of  FIG. 5  embodies three such run-time extending modifications to the embodiment  10  of  FIG. 1 . These three modifications may be used alone or as a combination to provide an optimal liquid reserve battery run time performance depending on the mission requirements. It will also be appreciated by those skilled in the art that one or more of these modifications may also be made to the embodiments  30 ,  50  and  70  of  FIGS. 2-4 , respectively. In the schematic of  FIG. 5 , all elements of the embodiment  80  are the same as those shown in the schematic of the embodiment  10  in  FIG. 1  and are identically enumerated, except the elements added to achieve the run-time extending modifications as described below. 
         [0069]    In the first of the modifications shown in the embodiment  80  of  FIG. 5 , a “heat storage” element  81  is provided that is heated by the heat generated by the pyrotechnic material  21  initiation during the liquid reserve battery activation. The heat storage element  81  is preferably made out of materials with high volumetric heat capacity that are either electrically non-conductive or are covered by a layer of electrically insulating material. The material must also be non-reactive to the liquid electrolyte. A good compromise may, for example, be ceramic. Then when the liquid reserve battery  80  is activated, the heat stored in the heat storage element  81  would keep the battery cell  15  and its liquid electrolyte above the operational temperature of the battery longer than it would without the heat storage element  81 . As a result, the run-time of the liquid reserve battery is increased. 
         [0070]    It is appreciated by those familiar with the art that the heat storage element  81  may be positioned anywhere within the battery cell  15  and even in the electrolyte compartment, including at or close to its wall surfaces of the battery cell  15 . In one configuration, the separating plate  14  is used to serve for this purpose, particularly for the embodiments such as  30 ,  50  and  70  of  FIGS. 2-4  that have relatively large such surface plates and battery cell  15  depths. The separating plate  14  can be constructed with materials with high volumetric heat capacity and appropriate amount of volume (mass). The use of the separating plate  14  as the heat storage element  81  has the advantage that it is close to the heat source and occupies minimal or no additional battery volume, thereby leads to the construction of volumetrically more efficient liquid reserve batteries. In such applications, the surfaces of the separating plate  14  facing the pyrotechnic materials is preferably increased by making it rough or by providing ridges or fins to increase its surface area, thereby allowing the separating plate  14  to absorb and store more heat. 
         [0071]    In the second of the aforementioned modifications shown in embodiment  80  of  FIG. 5 , at least one electrical heating coil element  82  is provided. The terminals of the heating coil element  82  are indicated with numerals  83  and connected to a power control system  84  by wires  85  such that when the voltage and/or current and/or power provided by the battery  80  drops below a predetermined amount (such as the performance level of the battery), electrical power (from the battery  80  or other power sources) is diverted to the coil  82  (the input power line to the power control system  84  is shown by the numeral  86 ) to heat the battery cell  15  and its liquid electrolyte. Alternatively and particularly for relatively larger liquid reserve batteries, a temperature sensor (not shown) may be used to determine when to power the coil element  82  and how much power to provide to the coil. Furthermore, such as for irregular shaped batteries  80 , several sensors/heaters may be employed in the battery cell  15  to ensure that all portions of the same are operating efficiently. 
         [0072]    In the third of the aforementioned modifications shown in embodiment  80  of  FIG. 5 , at least one pyrotechnic material filled container  87  is provided and can be positioned around the outer surface of the battery cell compartment  13  of the liquid reserve battery. Then when the voltage and/or current and/or power provided by the battery  80  drops below the predetermined amount, such as a performance level of the battery, the pyrotechnic material inside at least one of the containers  87  is igniter (preferably by an electrical igniters—not shown) to heat the battery cell  15  and its liquid electrolyte. Alternatively and particularly for relatively larger liquid reserve batteries, a temperature sensor (not shown) may be used to determine when the at least one pyrotechnic materials filled container  87  must be ignited. 
         [0073]    In many applications, the liquid reserve battery is required to provide full or close to full power a very short time after initiation. This capability is particularly challenging when the reserve battery is at very low temperatures such as the aforementioned −65 degrees F. For this reason, the electrolyte must be at relatively high temperature before it is injected into the battery cell since it is also required to provide the required amount of heat to rapidly heat the cell elements while staying warm enough to ensure proper operation of the reserve power source. The following embodiments are modifications of the embodiment  10  of  FIG. 1  to provide such a capability to liquid reserve batteries. As will be shown, the provided capabilities allows liquid reserve power sources to provide full power in a relatively short time following initiation as well as to keep the reserve power source fully active longer even in a very cold environment. 
         [0074]    The embodiment  100  shown schematically in the cross-section view of  FIG. 6  embodies one such fast activation and run-time extending modification to the embodiment  10  of  FIG. 1 . It will be appreciated by those skilled in the art that one or more of these modifications may also be made to the embodiments  30 ,  50  and  70  of  FIGS. 2-4 , respectively. In the schematic of  FIG. 6 , all elements of the embodiment  100  are the same as those shown in the schematic of the embodiment  10  in  FIG. 1  and are considered to be identically enumerated, except the elements added or modified which are enumerated accordingly in  FIG. 6  and as described below. 
         [0075]    In the first of the modification shown in the embodiment  100  of  FIG. 6 , the at least one outlet hole  19  (see  FIG. 1 ) is eliminated, thereby preventing the electrolyte  18  stored in the liquid electrolyte storage unit  17  to be directly discharged into the battery cell  15  upon the battery initiation as was previously described. At least one alternative outlet holes (ports)  101  are then provided as shown in  FIG. 6 , to allow the electrolyte  18  stored in the liquid electrolyte storage unit  17  to be discharged via the “heat exchanger elements”  102 . 
         [0076]    The aforementioned “heat exchanger elements”  102  may be constructed using any number of well-known shapes and structures commonly used in the design and construction of heat exchangers. As is well known in the art, such heat exchangers are designed to efficiently transfer heat from the outside of the heat exchanger, in this case from the sealed volume  22  to the fluid (in this case the electrolyte  18 ) through the heat exchanger (in this case the heat exchanger  102 ) through a combination of conduction and convection processes. For this reason, the surface area of the heat exchanger is desired to be as large as possible to maximize the heat transfer rate. The outside surfaces of the heat exchanger may also be provided, at least partially with fins elements. 
         [0077]    In the present liquid reserve battery embodiment of  FIG. 6 , this goal can be accomplished by providing the heat exchanger element  102  with relatively large surface areas. This can be done in numerous ways, two examples of which are provided here without intending to limit the options to the indicated designs. 
         [0078]    In the first example, the at least one heat exchanger element  102  is essentially a relatively long tube which is attached to a lower side of the liquid electrolyte storage unit  17  as shown in the schematic of  FIG. 6 . Then, when the reserve battery  100  is initiated and its internal pyrotechnic materials  21  are ignited to generate pressure inside the sealed volume  22  as well and heat the liquid electrolyte storage unit  17 , thereby heating the liquid electrolyte  18 , the surfaces of the at least one heat exchanger element  102  are also heated, thereby further heating the fluid electrolyte  18  inside the at least one heat exchanger element  102  as well as further heating the fluid electrolyte  18  as it passes through the at least at one heat exchanger element  102 . It is noted that as was previously described for the embodiment  10  of  FIG. 1 , the pressure generated by the initiation of the initiation device  23  and the pyrotechnic material, some of which may be mostly of gas generating type, would act over the surface of the at least one collapsible liquid electrolyte storage unit  17 , forcing it to collapse, thereby forcing the pressurized liquid electrolyte  18  to rupture the diaphragm(s)  103  separating it from the battery cell  15  and rapidly injecting the heated liquid electrolyte  18  into the cavities between the battery cell  15  electrodes as shown by the arrows  104 . The liquid reserve battery  100  is thereby activated very rapidly without the need for wicks or munitions spin or other additional means. In addition, the heating of the liquid electrolyte  18  (even if it is turned solid due to extreme cold temperatures) would allow activation of the liquid reserve battery  100  at very cold temperatures and ensures its high performance. The heating of the liquid electrolyte  18  would also enhance its diffusion rate inside the battery cell  15 . It will be appreciated by those skilled in the art that the relatively long heat exchanger tube(s)  102  may have any cross-sectional shape, including circular, oval, etc., but to provide larger surface area for a given cross-sectional area to increase the rate of heat transfer to the electrolyte fluid, a relatively flat oval shaped cross-sectional area can be used. Here, by flat, it is meant oval shapes in which the semi-major of the elliptical cross-section is significantly longer than its semi-minor axis. Such cross-sectional shapes are also readily manufactured. In addition, depending on the amount of heat to be transferred to the passing liquid electrolyte and the limitations on the length of the heat exchanger element due to space availability, the heat exchanger may be corrugated or provided with external fin rings (not shown) commonly used in tubular heat exchangers to increase the heat transfer rate to the passing liquid electrolyte. 
         [0079]    In the another example shown in the cross-sectional view and base view of  FIGS. 7A and 7B , respectively, the heat exchanger element  105  can essentially be an integral part of the collapsible liquid electrolyte storage unit  106 . The resulting heat exchanger integrated collapsible liquid electrolyte storage unit  107  can be made symmetric about the long axis of the unit as shown in the longitudinal cross-sectional view of  FIG. 7A  and the base view of  FIG. 7B . The base plate  108  of the unit  107  is then provided with at least one port  109  (four such ports are shown in the view of  FIG. 7B ) to provide outlet holes (ports) similar into the battery cell (similar to ports  101  and  19  of  FIGS. 7 and 1 , respectively). One of the advantages of the embodiment  100  of  FIG. 6  with the heat exchanger integrated collapsible liquid electrolyte storage unit  107  of  FIGS. 7A and 7B  is that it can be readily manufactured, particularly by seam welding of preformed layers as will be described later in this disclosure. In addition, it provides a relatively large heat exchanger surface area; the heat exchanger portion  105  of the integrated unit  107  can be designed to be partially collapsible, thereby assisting in the process of injecting the heated liquid electrolyte  18  into the battery cell  15 ; can provide multiple and properly distributed outlet holes (ports) to ensure a uniform and rapid distribution of the injected liquid electrolyte within the battery cell, thereby accelerating the process of battery activation. 
         [0080]    It will be appreciated by those skilled in the art that, when in the embodiment  100  of  FIG. 6 , the heat exchanger integrated collapsible liquid electrolyte storage unit  107  of  FIG. 7A  is used, then the relatively rigid plate  14  separating the compartments  12  and  13  of the battery (see the embodiment of  FIG. 1 ) may be an integral part of the unit  107 , i.e., form the base  108  of the heat exchanger integrated collapsible liquid electrolyte storage unit  107 . 
         [0081]    When it is desired to provide more heat to the liquid electrolyte  18  as it passes through the heat exchangers  102  or  105  of  FIGS. 6 and 7A , respectively, the outer surfaces of the heat exchangers may be covered by additional heat generating pyrotechnic material  110  as shown in the schematic of  FIG. 6 . 
         [0082]    In addition, the embodiment  100  of  FIG. 6  may be provided with a compressively preloaded spring  111  between the collapsible liquid electrolyte storage unit  17 ,  FIG. 1  (or the unit  106  of  FIG. 7A ) and the reserve battery body  11  as shown in the schematic of  FIG. 6 . To prevent the compressively preloaded spring  111  from applying pressure to the collapsible liquid electrolyte storage unit ( 17  or  106 ), readily combusting fabrics such as soft cotton fabrics and pyrotechnics materials  112 , which can be provided with any one of the known organic binders used in pyrotechnic materials, can be used to firmly hold the spring  111  in its compressively preloaded condition. Then, upon initiation of the reserve battery ( 10  and  100  of  FIGS. 1 and 6 , respectively), the pyrotechnic material and holding fabric combination  112  are also ignited, thereby releasing the compressively preloaded spring  111 . The compressively preloaded spring  111  will then further assist the pressurized compartment  12  to collapse the collapsible liquid electrolyte storage units to inject the heated electrolyte fluid  18  into the battery cell  15 . 
         [0083]    As was previously indicated, the heat exchanger integrated collapsible liquid electrolyte storage unit  107  of  FIG. 7A  (and similarly the collapsible liquid electrolyte storage unit  17  of  FIG. 1 ) may be manufactured by seam welding of preformed layers (sections) at relatively low cost. The cross-sectional view of an example of a heat exchanger integrated collapsible liquid electrolyte storage unit of this type  120  which is constructed very similar in shape to the heat exchanger integrated collapsible liquid electrolyte storage unit  107  of FIG.  7 A is shown in  FIG. 8A . The aforementioned preformed sections  113 ,  114 ,  115 ,  116 ,  117 ,  118  and  119 , which are seam welded to form the heat exchanger integrated collapsible liquid electrolyte storage unit  120  of  FIG. 8A , are shown in  FIG. 8B . The six seams  121  between the above seven preformed sections  113 - 119  to be welded are indicated in the schematic of  FIG. 8A . 
         [0084]    In addition, in certain applications, such as when the battery may be used at relatively high as well as very cold temperatures, and if the amount of heat generated by all pyrotechnic materials provided in the compartment  12  (including the pyrotechnic materials  110 ,  FIG. 6 , over the heat exchanger surfaces) for heating of the liquid electrolyte  18  may be excessive when the battery is activated at elevated temperatures, then a portion of the pyrotechnic material (which can include pyrotechnic material  110  covering the heat exchanger surfaces) can be covered by heat insulating material (such as a relatively thick layer of silica or carbide powder with any organic binder commonly used for such purposes as is well known in the art). In such configuration, a temperature sensor can be provided (not shown) inside or outside of the battery and used to initiate the ignition protected (heat insulation covered) pyrotechnic material via provided electrical initiation elements (such as the regularly used filaments) as is well known in the art. 
         [0085]    It will also be appreciated by those skilled in the art that the at least one heat exchanger “tube” element  102  could be extended into the cell  15  compartment  13  (see  FIG. 1 ) thereby providing heat to the cell  15  as well as injecting the liquid electrolyte  18  further into the core of the battery cell  15 . 
         [0086]    It will further yet be appreciated by those skilled in the art that the battery cell  15  may be heated internally by heat generating pyrotechnic materials as can be seen in the embodiment  130  of the schematic of  FIG. 9 . The embodiment  130  shown schematically in the cross-section view of  FIG. 9  illustrates a fifth modification to the embodiment  10  of  FIG. 1 . It will also be appreciated by those skilled in the art that one or more of these modifications may also be made to the embodiments  30 ,  50  and  70  of  FIGS. 2-6 , respectively. In the schematic of  FIG. 6 , all elements of the embodiment  100  are the same as those shown in the schematic of the embodiment  10  in  FIG. 1  and are considered to be identically enumerated, except the elements added or modified which are enumerated accordingly in  FIG. 9  and as described below. 
         [0087]    In the embodiment  130  of  FIG. 9 , the liquid reserve battery is provided with at least one heat exchanger tube  122  similar to the heat exchanger elements  102  of the embodiment of  FIG. 6 , which is at least partially filled with heat generating pyrotechnic material  123 . The pyrotechnic material  123  may be provided with its separate initiation (such as an electrical initiation) element (not shown), or can be ignited by the initiated pyrotechnic material  21  inside the compartment  12  of the battery (see  FIG. 1 ) following the reserve battery initiation as was previously described for the embodiment  10  of  FIG. 1 . In such configuration, an end  124  of the heat exchanger tube  122  can be closed, while its other end  125  is open into the sealed volume  22  of the compartment  12  of the battery. Then, the pyrotechnic material  123  inside the heat exchanger tube  122  will be ignited by the initiated pyrotechnic material  21  following the battery initiation. Otherwise, the pyrotechnic material  123  may be initiated separately by its own initiation device as was previously indicated, such as via an input from the aforementioned temperature sensor(s) if extra heat is required for heating the battery core  15  for its proper operation. 
         [0088]    It will be appreciated by those skilled in the art that the at least one heat exchanger tube  122  may be required to be made out of, or be covered by, electrically nonconductive material to ensure proper operation of the battery cell. In addition, the at least one heat exchanger tube  122  may have any appropriate cross-sectional area and can be small in cross-section and long enough and “wound around” the interior of the cell  15  to nearly uniformly heat the battery cell volume  15 . 
         [0089]    While there has been shown and described what is considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.