BACKGROUND OF THE INVENTION

[0001] This invention relates generally to a power pack which, in this specification, is intended to include an assembly of batteries. In particular the invention relates to a power pack which is more resistant to unauthorised access and theft than a conventional power pack.

[0002] Batteries, and in particular rechargeable batteries, find numerous applications. For example a cellular telephone network includes a large number of cells each of which is powered by a suitable primary energy source. If a primary energy source, e.g. a mains power supply or a diesel driven generator, should fail then continuity of operation can be maintained by switching over to an assembly of back-up batteries, i.e. to a suitable power pack.

[0003] Lead acid batteries are in widespread use. Typically each battery includes a case which is manufactured from a suitable plastics material such as ABS or PPO (polyphenylene oxide) in which an electrical energy storage arrangement, which includes a plurality of lead plates, is kept. Each battery provides a specified voltage e.g. 12 volts and , normally, four batteries are connected to one another in series, using suitable links, to provide an assembly with an operating voltage of 48 volts. The batteries are made in standard sizes so that irrespective of the source of supply the batteries can be mounted inside industry standard cabinets or racks e.g. with dimensions of 23" or 9".

[0004] Each battery weighs about 60 kg and, when the batteries are interconnected by the links, the assembly has a mass of the order of 240 kg. It is not really possible for the four interconnected batteries to be moved in unison. [0005] The batteries, in working order, have substantial value. Apart therefrom the quantity of lead in each battery is significant and the lead, as scrap metal, is also valuable. The batteries are therefore prone to theft.

[0006] Typically a thief who wants to steal a battery would cut the links so that each battery could then be removed separately from the installation location. To combat this some form of anchoring arrangement is required. Each battery case however is relatively smooth and has no protrusions or hard points other than two electrical terminals on a top of the case. Very little space is available in a standard 23" cabinet or rack which can be utilised to secure a battery in position and so render it less liable to be stolen. [0007] An object of the present invention is to address, at least to some extent, the aforementioned problem.

SUMMARY OF THE INVENTION

[0008] The invention provides a power pack which includes at least a first battery, a second battery which is positioned adjacent and spaced from the first battery, and first structure which secures the first battery to the second battery in a non-releasable manner and which allows air to flow between the first and second batteries.

[0009] The power pack may include a third battery which is positioned adjacent and spaced from the second battery and second structure which secures the second battery to the third battery in a non-releasable manner and which allows air to flow between the second and third batteries. Similarly the power pack may include a fourth battery which is positioned adjacent and spaced from the third battery and third structure which secures the third battery to the fourth battery in a non-releasable manner and which allows air to flow between the third and fourth batteries.

[0010] Each battery is preferably of parallelepiped form, ie. viewed from above, from one side and from the front, the battery in each instance is generally rectangular in outline. [0011] The first battery may present a planar substantially rectangular or square side to a similar opposing planar substantially rectangular or square side of the second battery, and so on. The first structure preferably has at least a first surface which is secured to the said side of the first battery and at least a second surface which is secured to said similar opposing side of the second battery. [0012] The first structure may be secured to the first battery and to the second battery in any appropriate way and preferably use is made of an appropriate adhesive. Preferably the adhesive does not display any significant thermal insulating properties but, instead, is capable of conducting heat generated in the first battery and in the second battery so that air which passes between the batteries can remove such heat and direct it to atmosphere. [0013] The first structure may be of any suitable form and preferably has a single surface or a combination of surfaces of a substantial area which abuts and which is bonded to the said side of the first battery. Similarly the first structure may have a single surface or a combination of surfaces of substantial size which abuts and which is bonded to said similar opposing side of the second battery. [0014] The first structure may be shaped so that at least one gap is formed, e.g. between opposing surfaces of the first structure, or between opposing surfaces of the batteries, or between opposing surfaces of the first structure and of one or both batteries, through which air can pass.

[0015] Preferably air flow takes place, at least, in a generally vertical direction.

[0016] The second structure and the third structure may for all practical purposes be the same as the first structure.

[0017] The invention also extends to a power pack which includes a plurality of substantially similar batteries, each battery being of generally parallelepiped form, and a plurality of securing structures, wherein the batteries are positioned side by side one another with a gap between each adjacent pair of batteries and, within each gap, a respective said securing structure is bonded to opposing surfaces of the adjacent batteries and wherein the securing structures allow for airflow to take place through at least part of the gaps. Preferably such airflow takes place in a generally vertical direction.

[0018] In one preferred embodiment each said securing structure includes first and second spaced-apart members with respective outer surfaces which, in use, are bonded to respective opposing surfaces of two adjacent spaced-apart batteries and at least one connecting member which connects the first member to the second member

[0019] The invention also extends to a method of assembling a power pack which includes a cabinet, a plurality of batteries and a plurality of securing structures, wherein the method includes the steps of positioning a first said battery inside the cabinet, adhesively securing a first part of a first said securing structure to an exposed side of the first battery, locating a second said battery in the cabinet, adhesively securing a second part of the first securing structure to an exposed side of the second battery so that the first battery and the second battery are secured to each other and are spaced apart by the first securing structure, adhesively securing a first part of a second said securing structure to an exposed side of the second battery, locating a third said battery in the cabinet, and adhesively securing a second part of the second securing structure to an exposed side of the third battery so that the third battery and the second battery are secured to each other and are spaced apart by the second securing structure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention is further described by way of examples with reference to the accompanying drawings in which:

Figure 1 illustrates from one side and in elevation a battery which is included in a power pack according to the invention,

Figure 2 illustrates in plan a power pack, according to the invention, which includes four batteries each of the kind shown in Figure 1 , installed in a rack or cabinet,

Figure 3 shows the power pack of Figure 2 in elevation, i.e. in the direction of an arrow marked "3" in Figure 2,

Figure 4 illustrates in perspective securing structure which is used in the power pack of the invention, and

Figures 5 and 6 illustrate, in plan, different types of securing structures which are used for interconnecting batteries in power packs according to the invention. DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] Figure 1 of the accompanying drawings illustrates in elevation a battery 10 which is one of a number of similar batteries included in a power pack 12 according to the invention - see Figure 2. [0022] The battery 10 includes a case 14 which contains a lead acid arrangement, as is known in the art, for electrical energy storage. An understanding of the electrical energy storage arrangement is not necessary for an understanding of the invention. It is, however, pointed out that the lead contained in the arrangement is a valuable commodity and that this makes each battery a possible theft target particularly when the battery is installed at a location, e.g. a cell tower, which is remote and not often policed.

[0023] The case 4 is made from an appropriate plastics material such as ABS or PPO and has a parallelepiped form. The case 14 has a front end 16, a rear end 18 (see Figure 2) . an upper end 20, a lower end 22 and opposed sides 24 and 26 respectively. Electrical terminals 28 and 30 are provided on the upper end 20 close to the front end 16. The aforementioned features are standard and are typical of existing batteries and cases.

[0024] Figure 2 illustrates in plan four batteries 1 0A, 10B, 10C and 10D respectively positioned inside a cabinet or rack 40 which has standard dimensions. Each battery is substantially the same as the battery 10 shown in Figure 1 . The respective terminals 28 and 30 at the upper end of each of the batteries are interconnected in series by means of appropriate conductive links, not shown, as is known in the art, to provide an operating voltage of 48V. [0025] It Is pointed out that values given in this specification are exemplary only and are non- limiting.

[0026] The batteries 10A to 10D are positioned so that, between each respective adjacent pair of batteries, respective gaps 42, 44 and 46 are formed. This is important for, in use, a substantial quantity of heat is generated as each battery is charged and discharged and this heat, unless extracted by convection air currents, can cause the temperature in a battery to rise to a value which is sufficiently high for the battery to be damaged or destroyed.

[0027] The power pack 12 includes three securing structures 52, 54 and 56 respectively positioned in the respective gaps 42, 44 and 46. The securing structures are substantially identical to each other. Figure 4 shows the securing structure 52 in perspective.

[0028] The securing structure 52 is made from relatively thin sheet metal which is formed to have two opposing parallel sheets 64 and 66 respectively which are joined to each other along adjacent vertically extending edges 64A and 66A by means of a connecting member 68 which comprises a relatively narrow vertically extending strip of sheet metal. In plan therefore the structure 52 has an elongate U-shape. Although the structure could be made from shaped sheets of material which are joined together it is preferable to form the structure integrally i .e. from a single sheet of metal which is folded in the desired manner.

[0029] The sheets 64 and 66 are planar and, preferably, are substantially equal in area to each other and equal in area to the area of the sides 24 and 26 of each battery. [0030] In order to assemble the power pack 12, shown in Figures 2 and 3. the first battery 10A is placed into the cabinet 40. An appropriate adhesive is then applied to at least a part, but preferably the whole, of an outer side 64X of the sheet 64 and, similarly to an outer side 66X of the sheet 66. The adhesive-carrying securing structure is then positioned in the cabinet 40 with the adhesive-clad side 64X abutting the exposed side 24A of the battery 10A (Figure 3). The battery 10B is then placed into the cabinet with its outer side 26B abutting the adhesive-clad surface 66X of the securing structure. [0031] The securing structure 54, with adhesive which is applied to its outer sides in a similar manner to what has been described, is then placed into the cabinet and the appropriate side of the securing structure 54 is brought into contact with the exposed outer side 24B of the battery 10B. The battery 10C is then placed into the housing and is brought into contact with the remaining adhesive-clad surface of the securing structure 54. In a similar manner the securing structure 56 is placed into position and this is followed by the battery 10D which is then brought into adhesive contact with the securing structure 56.

[0032] The cabinet has an upper side 47 and a rear side 49 which each prevent, or at least hinder, access, to a respective gap, and thus to each securing structure, between each adjacent pair of spaced apart batteries, from above. [0033] The mass of each battery is substantial, eg. of the order of 60kg. Also, little space is available inside the cabinet or rack 40 although, as noted, there is sufficient space inside the cabinet to accommodate the four batteries with a small gap between adjacent batteries for cooling purposes. Due to the constraints imposed by the mass of each battery and the limited space available for the batteries it is not generally feasible to fix the securing structures to the batteries and so make up a power pack for batteries which are interconnected by the security structures, unless the batteries and security structures are in position inside the cabinet Thus, at least for practical reasons, a power pack is built, in situ, in the casing, by successively placing batteries and then securing structures into the cabinet. [0034] The adhesive which is used is preferably of a heat-conductive nature. Heat which is generated during charging and discharging of each battery is transferred to the securing structure which, as noted, is metallic and which is therefore heat-conductive. Each securing structure has a large area and heat transfer takes place readily from each battery to the respective large area sheet of the associated securing structure.

[0035] To ensure effective heat transfer and bond strength each securing structure is preferably bonded over a maximum area to adjacent batteries. The bond strength of the adhesive, over the extended area referred to, is substantial and, for practical purposes, each battery is bonded more or less permanently to the respective securing structure. [0036] The connecting member 68 is positioned inside the casing adjacent inner ends of the respective batteries and close to or abutting a rear wall of the casing. Thus the connecting member 68 cannot readily be accessed by an intruder. A gap which exists between opposing surfaces of the sheets 64 and 66 is narrow and thus acts as an effective barrier which prevents an intruder from accessing the connecting member 68 with a tool which could be used to break the connecting member. The sheets 64 and 66 are close to one another but nonetheless are sufficiently far apart to allow airflow to take place between the sheets generally in a vertical direction for battery cooling purposes.

[0037] The three securing structures secure four batteries together to make up a power pack according to the invention. The mass of the power pack is of the order of 240kg . This is a substantial mass. Thus the power pack cannot readily be moved manually out of the cabinet, particularly given the small clearances which exist inside the cabinet. [0038] The securing structure shown in Figure 4 is exemplary only and other securing structures can be used to interconnect adjacent batteries, in the power pack, to achieve similar benefits to what have been described. For example, Figure 5 illustrates, in plan, four batteries 10A, 10B, 10C and 10D respectively which are spaced apart from one another, generally in the manner which is shown in Figure 2, inside a cabinet 40. In this instance securing structures 72, 74 and 76 respectively are used to interconnect opposing adjacent surfaces of the respective batteries to each other. The securing structures are generally identical to one another. Each securing structure includes a number of vertically extending tubular members 80, 82, 84, etc. which are bonded to opposing surfaces of the respective sheets 64, 66 of a structure 52. Alternatively the structure 52 is not used and the members are directly bonded to the respective surfaces of the batteries. The members are positioned to define gaps 86, 88, etc. between adjacent pairs of members which allow airflow to take place between the adjacent batteries in a vertical direction. The members 80 to 84 could be of any appropriate shape, e.g . square, rectangular or round in cross-section and may vary in size to ensure that an adequate bond strength is established between adjacent batteries.

[0039] If desired the members can be interconnected in a horizontal direction by means of thin cables or rods 90 in order to hinder or prevent an intruder from successively dislodging members from the adjacent batteries by breaking the adhesive bonds between the members and the batteries. [0040] Figure 6 illustrates in plan another type of securing structure 92 which is positioned between adjacent batteries 10A and 10B. Similar structures are used between other adjacent pairs of batteries. The securing structure 92 has a generally corrugated form, viewed in plan , which defines successive flat vertically extending surfaces 96A, 96B and 96C and displaced surfaces 98A, 98B, etc. The surfaces 96 etc., and 98 etc., are bonded to the respective sheets 64,66 (as shown), or directly to a side of the respective battery. Vertically extending channels 100 formed by the arrangement allow for vertical flows of cooling air to extract heat from the batteries during use and to discharge this heat to atmosphere. [0041] A benefit of the invention lies in the fact that the inventive principles can be used with existing and with new installations. As the case of each battery fits closely into a standard cabinet, when installed, the securing structures cannot readily be accessed from above and can be only accessed to a limited extent from the front. An existing standard cabinet or rack is or can be employed without requiring any modification. Due to the significant mass of the power pack and the limited access, the likelihood that the power pack can be levered from a cabinet is significantly reduced.