GB1569410A

GB1569410A - Electric storage batteries

Info

Publication number: GB1569410A
Application number: GB52461/75A
Authority: GB
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1975-12-20
Filing date: 1975-12-20
Publication date: 1980-06-11

Description

(54) ELECTRIC STORAGE BATTERIES (71) We, LUCAS INDUSTRIES LIMITED, a British company of Great King Street, Birmingham B19 2XF do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to electric storage batteries and, in partIcular, lead-acid batteries.

In a first aspect, the invention resides in an electric storage battery including an opentopped, thermoplastic resin battery box divided into cell compartments by partition walls intergral with the box, packs of battery plates and separators located within the cell compartments, the electrical connections between battery plates in adjacent cell compartments being made through the partition walls, a thermoplastic resin lid secured to the top peripheral edge of the box and the tops of the partition walls by friction welding, and a pair of terminal members connected to battery plates in the end cell compartments respectively of the box and extending through respective apertures in the lid, each terminal member defining a space with the wall of its associated aperture and each space being at least partially filled by a thermoplastic resin element separate from the lid so that the aperture is sealed.

In a second aspect, the invention resides in an electric storage battery including an open topped, thermoplastic resin battery box divided into cell compartments by partition walls integral with the box, packs of battery plates and separators located within the cell compartment, the electrical connections between battery plates in adjacent cell compartments being made through the partition walls, a thermoplastic resin lid secured to the top peripheral edge of the box and the tops of the partition walls by friction welding, and a pair of terminals connected to battery plates in the end cell compartments respectively of the box and extending through respective external walls of the box.

In a further aspect, the invention resides in the method of manufacturing an electric storage battery comprising the steps of: (a) starting with a thermoplastic resin, open topped battery box having integral partition walls dividing the box into cell compartments in which packs of battery plates and separators are received, the required intercell connections being made through the partition walls, and a pair of terminal members being connected to respective sets of said battery plates in the end cell compartments respectively of the box and projecting beyond the top peripheral edge of the box, and (b) pressing against the box a thermoplastic resin lid having a peripheral surface which engages the top peripheral edge of the box and ribs which engage the tops of the partition walls, said terminal members extending through respective apertures in the lid with a space being defined between each terminal member and the wall of its associated aperture, (c) simultaneously with said (b), imparting relative cyclic translatory movement to the lid and the box in the plane of the open top of the box to frictionally heat, and thereby soften, the interengaging surfaces of the lid and the box, the space between the terminal members and the walls of their respective apertures being sufficient to permit said movement.

(d) ceasing said relative movement and pressing the lid onto the box to secure the lid to the box, and then, (e) at least partially filling the space between each terminal member and the wall of its associated aperture with a thermoplastic resin element separate from the lid so that the element seals said aperture.

In a fourth aspect, the invention resides in a method of manufacturing an electric storage battery comprising the steps of: (a) starting with a thermoplastic resin, opentopped battery box having integral partition walls dividing the box into cell compartments in which packs of battery plates and separators are received the required intercell connections being made through the partition walls, and respective sets of said battery plates in each end cell compartment of the box being con nected to a respective terminal member which terminates short of the open top of the box, (b) pressing against the box a thermoplastic resin lid having a peripheral surface which engages the top peripheral edge of the box and ribs which engage the tops of the partition walls, (c) simultaneously with step (b), imparting relative cyclic translatory movement to the lid and the box in the plane of the open top of the box to frictionally heat, and thereby soften, the engaging surfaces of the lid and the box, (d) ceasing said relative movement and pressing the lid onto the box to secure the lid to the box, and (e) before or after step (b), completing the terminals of the battery by connecting said terminal members through respective external walls of the box to further terminal members respectively located at the external surface of the box.

Preferably, the relative cyclic translatory movement imparted to the lid and the box is linear reciprocating movement and more preferably, where the partition walls extend parallel with each other is in a direction parallel with the partition walls.

Preferably, the linear reciprocating movement has an amplitude between 0.1 and 0.25 inch or more preferably between 0.12 and 0.2 inch.

Alternately, the relative cyclic translatory movement is angular reciprocating movement.

Alternatively, the relative cyclic translatory movement follows a Lissajous figure, such as an orbital path.

Preferably, the pressure applied during step (b) is between 150 and 300 p.s.i., or more preferably between 200 and 250 p.s.i.

Conveniently, steps (b) and (c) are performed with the cell compartments containing the electrolyte of the finished battery, the box then being held stationary during step (c) while the required cycle translatory movement is imparted to the lid.

Conveniently, the method includes the further steps of positioning packs of battery plate grids, with said separators interposed therebetween, within said cell compartments, the grids carrying the battery paste required to poduce said battery plates after conversion of the paste into the active material of the plates, and, after completion of the intercell connections, forming the grids within the box into said battery plates by converting the paste on the grids into the active material of the plates.

In the accompanying drawings: Figure 1 is a perspective view of a battery box illustrating assembly of a pack of battery plates and separators into the box during a method according to one example of the invention; Figure 2 is a sectional view of part of the battery box illustrating the completion of the intercell connections during the method shown in Figure 1, Figure 3 is a sectional view of part of a battery lid for use with the battery box shown in Figure 1, Figure 4 illustrates diagrammatically joining of the lid to the box in the method of said one example, Figure 5 is a sectional view illustrating formation of a terminal of the battery at a later stage in the method of said one example, Figure 6 is a sectional view illustrating formation of a battery terminal in a method according to a second example of the invention, and Figures 7 to 16 are sectional views illustrating alternative ways of sealing the battery terminals to that illustrated in Fig. 5.

Referring to Figures 1 to 5, the battery to be produced is a lead-acid battery and includes a battery box 11 moulded from polypropylene or other suitable thermoplastic resin so that the box is divided into six cell compartments by spaced, parallel partition walls 12. Each compartment receives a preformed pack 13 of battery plates and separators, the plates being arranged in each pack 13 in sets of positive battery plates and negative battery plates respectively. In each of the four packs which are to be assembled in the central compartments of the box 11, the two sets of plates are connected to connecting lugs 15, 16 respectively. Each of the lugs 15, 16 is formed with an integral extension which, in use, extends substantially parallel to the partition walls 12 and each of the lugs 16 is further formed with a projection 16a integral with its respective extension. Each of the packs 13 which is to be placed in an end compartment of the battery box has one set of plates connected to a lug 15 or 16, the other set of plates being connected to a cylindrical lead terminal post 17 which projects from the open top of the box.

As shown in Figure 2, the partition walls 12 have holes 12a pierced therein and arranged so that when the packs 13 are assembled in the box 11 each projection 16a extends through a hole 12a into engagement with the extension of a lug 15 in an adjacent compartment. Of course, it will be appreciated that the partition walls 12 have to be flexed to permit the packs 13 to be placed into the box 11.

When all the packs 13 are in position, the required intercell connections are completed using the resistance welding tool shown at 18 in Figure 2. The tool 18 includes a pair of electrodes 21, 22 which are engaged in turn with the extensions respectively of each pair of lugs 15, 16 to resistance weld the lugs together. During such a resistance welding operation, the electrodes 21, 22 simultaneously press the extensions of the lugs 15, 16 against their respective partition wall 12 and pass each space, or more preferably, preformed bushes 30 are friction welded to the internal surfaces of the respective spigots 27 and secured to the terminal posts 17, as shown in Figure 5. Although not shown in the drawings, each bore 28 tapers inwardly towards the lid 29 whilst each terminal post 17 is tapered in the opposite direction, i.e. it tapers upwardly as viewed in the drawings. The surface of that portion of the post 17 which lies within the bore 28 is knurled, splined or otherwise roughened. The inner and outer surfaces of the bushes 30 are tapered in a a corresponding manner to the respective bores 28 and posts 17. Each bush 30 is slightly oversize with respect to its respective bore 28 and has ribs at its outer and/or inner surface.

Thus, referring to Figure 5, each bush 30 is first pushed over the free end of the associated post 17 until the bush enters the respective bore 28. Being slightly oversize, the bush 30 binds against the wall of the bore 28 before its lower surface engages the lip 29. The bush 30 is then rotated relative to the lid 23 whilst at the same time being pressed downwardly. Friction is thereby generated between the ribs on the bush 30 and the wall of the bore 28 and between the inner surface of the bush 30 and the roughened portion of the post 17 which causes melting of the ribs and inner surface of the bush 30 and of the wall of the bore 28, the molten resin produced effecting a seal between the spigot 27, bush 30 and post 17. The rotation of the bush 30 is stopped when the lower end thereof is in engagement with the lip 29. Thus, when the molten material solidifies, the bush 30 is welded to the spigot 27 and hence is held against rotation relative to the lid 23, the roughened surface on the terminal post 17 serving also to key the bush 30 to the post 17.

At this stage, the terminal posts 17 are arranged to project beyond their respective bushes 30, and when welding is complete, the projecting ends of the posts 17 are peened or spun over to further secure the posts relative to the bushes and enhance the seal between the posts and the bushes. The external electrical connections to the battery can then be made to the deformed ends of the terminal posts.

In the method described above, the sulphuric acid electrolyte required in the finished battery is introduced into the cell compartments of the box 11 after the lid 23 has been welded to the battery box. It is, however, to be appreciated that, as an alternative, the electrolyte can be introduced into the box prior to welding of the lid. In this case, unless special care is taken during the introduction of the acid, some acid is inevitably deposited at the top peripheral edge of the box and the tops of the partition walls 12. It is, however, found that these acid deposits do not interfere with the production of a satisfactory friction welded joint between the box and the lid.

As a further alternative to the method described above, the packs 13 initially introduced into the box 11 can be made up of separators and battery plate grids carrying lead-acid battery paste in a non-formed condition. The grids must therefore be subjected to a subsequent forming operation to convert the paste into the active material of the required battery plates.

In this alternative method, each grid is either connected to a lug 15 or 16 and the intercell connections are completed in the same way as described above. However, after completion of the intercell connections, each cell compartment of the box 11 is first filled with a sulphuric acid solution, conveniently having a specific gravity 1.050, and the terminal posts 17 are connected to a d.c. supply. Current is then passed through the battery to convert the paste on the grids into the active material of the plates, whereafter the sulphuric acid solution is removed from the box 11. Conventional battery acid can then be introduced into the box before or after welding of the lid. Alternatively, the acid used for the forming operation can be retained to define the electrolyte of the finished battery, provided of course the forming acid is chosen so as to have the required specific gravity after the formation process is complete.

Referring now to Figure 6, in a modification of the above example, one set of plates in each end cell compartment of the box 11 is connected to a terminal member 37 in the form of a plate-like extension of one of the connecting lugs 15 or 16. Each member 37 extends adjacent to and parallel with one external wall 11b of the box and is providedwith a pair of integral projections 38 which extend into respective apertures 39 in the wall llb. The projections 38 are resistance welded, conveniently using the tool shown at 18 in Figure 2, to a further terminal member 41 which is located at the external surface of the wall 11b to provide one of the external terminals of the battery.

Due to the relatively large gap between the outer surface of each terminal post 17 and the inner edge of the respective lip 29, there may be a tendency for molten material to flow through the bore 28 and into the battery cell compartments. Thus, a modified terminal post seal is preferred in which this gap is closed or at least narrowed sufficiently to prevent such flow. Examples of such a modified seal are illustrated in Figs. 7 to 16.

Referring now to Fig. 7, an injection moulded thermoplastic resin element 730 is provided in the bore 28 around the terminal post 17.

Flow of resin during the injection moulding process through the annular space between the terminal post 17 and the lip 29 is limited by the provision of a sleeve 750 which may be of lead but is preferably of resin. The sleeve 750 may be inserted before or after current between the extensions through the projection 16a so that the projection melts and seals the hole 12a in the partition wall. It is of course to be appreciated that other arrangements than that described above can be used for providing the intercell connections through the partition walls.

When the intercell connections are complete, the box 11 is closed with a lid 23 by friction welding the lid to the box. The lid 23 is also moulded in polpropylene or other suitable thermoplastic resin and, as shown in Figure 3, includes a peripheral skirt 24 which extends at right angles to the plane of the lid to define a peripheral edge surface 25 at its free end and an intermediate peripheral abutment surface 24a disposed inwardly of the edge surface 25. When the lid 23 is secured to the box 11, the abutment surface 24a engages the free ends of the external walls of the box 11 whilst the edge surface 25 lies opposite a projecting flange lia on the box 11. Transversely extending ribs 26 projecting downwardly from the top of the lid 23 engage the free or top edges of the partition walls 12 of the box. The portions (not shown) of the abutment surfaces 24a which extend along the longitudinal side edges of the box 11, i.e. at right angles to the ribs 26, are sufficiently wide as to permit linear reciprocating movement of the lid 23 relative to the box 11 as will be described hereinafter.

In addition, the lid is formed integrally at its inner surface with a pair of depending hollow spigots 27 (only one shown), the bore 28 in each spigot 27 communicating with the outer surface of the lid to define an aperture in the lid for receiving one of said electrode posts 17. Moreover, the wall of each bore 28 is stepped so as to define an inwardly directed lip 29 at the free end of the spigot.

To friction weld the lid 23 to the box 11, the apparatus illustrated diagrammatically in Figure 4 is employed. The apparatus includes a conveyor (not shown) on which the box 11, with the lid 23 loosely carried thereby, is transported to a welding station where a first die part 31 moves through the conveyor to engage and retain the box 11. A second die part 32 spaced vertically above the first die part 31 then moves down to engage and retain the lid 23, the die part 32 being carried by a platen 33 which is formed of magnetic material and which is supported by resilient bars 34 depending from a carrier 35. Positioned on opposite sides respectively of the platen 33 are a pair of electromagnets 36, the windings of which are connected to an a.c. supply so that, when the supply is energised, the platen 33 is moved by magnetic attraction towards the electromagnets 36 alternately. The lid 23 is thereby caused to undergo linear reciprocating movement relative to the box 11 in the plane of the open end of the box and parallel with the partition walls 12 and the lid 23- simul taneously being pressed against the box so that frictional heat is generated between the interengaging surfaces.

Preferably, the vibration of lid 23 is arranged to have an amplitude of between 0.1 and 0.25 inches, or more preferably between 0.12 and 0.2 inches, and a frequency of about 100--120 cps. The pressure applied to the lid 23 during the vibration is preferably between 150 and 300 p.s.i., or more preferably between 200 and 250 p.s.i. The vibration is continued until the interengaging polypropylene surfaces soften or become molten, which normally takes about 6 seconds, whereupon the vibra option is ceased and the lid 23 is pressed against the box to form the required welded joint therebetween. After a hold time of about 1 second, the pressure is released and the die part 32 is disengaged from the lid 23 and returned to its original position. The die part 31 is then lowered to return the box 11, with the lid 23 welded thereto, to the conveyor whereupon the cycle is repeated.

In order to increase the strength of the weld between the box 11 and the lid 23, it may be desirable to provide the tops of the extenral walls of the box 11 and the partition walls 12 with thickened portions. Corres pondingly thickened portions may also be pro vided at the free ends of the ribs 26 and abutment surface 24a. In addition, the abut ment surface 24a of the skirt 24 and the free or top edge of the external walls of the box may be formed with recesses (not shown) for receiving the excess molten material which is displaced when the lid is pressed against the box to complete the welded joint. In this way, the formation of flash around the extemal edge of the join can be avoided.

It is to be appreciated that, although the movement imparted to the lid 23 to effect friction welding in the above example, is linear reciprocating movement, the lid could alternatively be reciprocated angularly relative to the box. As a further alternative, the lid 23 could be caused to move along a Lissajous figure such as an orbital path. In such cases, appropriate changes are made to the widths of the abutment surface 24a and ribs 26 to accommodate such movements.

Since welding of the lid 23 to the box 11 involves reciprocation of the lid relative to the box, it is necessary to ensure that the diameter of each terminal post 17 is less than the diameter of its associated bore 28 includ ing the portion thereof defining the lip 29.

Thus when the lid is secured in position the end cell compartments are open to atmos phere and must therefore be sealed. This is effected by filling the space defined between each terminal post 17 and the wall of its associated bore with an annular, thermo plastic resin bush 30 formed separately from the lid. Each bush 30 is either produced in situ by injecting a thermoplastic resin into fitting of the lid 23 onto the box 11. If fitted before, the sleeve 750 must be clear of the bore i8. If fitted after, it can project into the annular space. In Fig. 8, a sleeve 850 similar to sleeve 75Q and a spin friction, welded thermoplastic resin element 830 similar to element 30 are provided. The sleeve 850 limits flow of molten resin through the annular space between the lip 29 and the post 17 and thereby enhances flow of molten resin upwardly into the space between the post 17 and the element 830 so as to improve the seal therebetween. Alternatively, the aforesaid annular space may be closed by a wedgeshaped annular seal 950 which rests on the lip 29 and abuts against the post 17 (Fig. 9).

On the left-hand side of Fig 9, an injection moulded thermoplastics resin element 930a is illustrated. On the right hand side of Fig. 9 a spin friction welded thermoplastics element 930b is illustrated. An annular recess 951 is provided in the element 930b to accommodate the seal 950. The seal 950 is located in position after the lid 23 has been friction welded to the box 11.

In Fig. 10, the aforesaid annular space is sealed by a sleeve 1050 formed of lead. The lower end of the sleeve 1050 has a radially outwardly projecting integral annular rib 1052 which rests on the upper surface of the lip 29 whilst the upper end of the sleeve 1050 has a radially inwardly directed integral annular rib 1053 which overlies the terminal post 17.

A thermoplastic resin element 1030 is injection moulded in situ around the sleeve 1050 to effect a seal in the bore 28 externally of the sleeve 1050. A seal between the post 17 and the sleeve 1050 is effected by melting the rib 1053 and at the same time, or subsequently, peening over in the manner described hereinabove. In Fig. 11, a sleeve 1150 has a rib 1153 similar to rib 1053 but which rests on the post 17. However, the sleeve 1150 is not provided with a rib at its lower end and merely projects into the aforesaid annular space. A thermoplastic resin element 1130 with the sleeve 1150 inserted therein is spin friction welded into position in the bore 28. The seal between the sleeve 1150 and the post 17 is effected as described in Fig. 10.

In Fig. 12, a sleeve 1250 is provded which has a slightly tapered bore 1254 mating with a slight taper on the terminal post 17. A radially outwardly directed lip 1252 similar ro lip 1052 is provided in the sleeve 1250. A thermoplastic resin element 1230 is in situ injection moulded into the bore 28 around the sleeve 1250 so as to enter an annular recess 1255 defined between the lip 1252 and a portion 1256 which is splined and/or of non-circular (e.g. hexagonal) cross-section.

The portion 1256 of the sleeve 1250 lies within the bore and is covered with the injected resin so that rotation of the sleeve 1250 relative to the element 1230 is resisted.

If desired, the bore 28 may be splined and/or of non-circular (e.g. hexagonal) cross-section to limit rotation of the element 1230 relative to the lid 23. An externally tapered surface 1256 of the sleeve 1250 projects above the element 1230 and corresponds in shape to the final terminal shape. The terminal is then finished by pouring molten lead into the portion of the bore 1254 which projects above the top of the post 17.

In Fig. 13, a thermoplastic resin element 1330 is formed around a sleeve 1350 which is of a similar external shape to but shorter than the sleeve 1250. The sleeve 1350 has an untapered bore 1354 and the post 17 is externally untapered. The element 1330 has an axially extending annular rib 1357 projecting at its lower end, the rib 1357 projecting into the aforesaid annular space so as to limit the passage of molten resin therethrough and to provide sealing between the element 1330 and the post 17.

In Fig. 14, the terminal post 17 is cast with an integral radially outwardly projecting annular rib 1452 which is disposed below the lip 29 of the lid 23. The post 17 is also cast with a frusto-conical head portion 1450 whose lower end is disposed in the bore 28 and which defines with the rib 1452 an annular recess 1455. Splining 1458 is provided on the post 17 in the recess 1455. After the friction welding operation by which the lid 23 is secured to the box 11, the rib 1452 is sufficiently close to the underside of the lip 29 to limit or prevent flow of resin material from an in situ injection moulded thermoplastic resin element 1430 through the aforesaid annual space.

In Fig 15, the terminal post 17 has an annular rib 1552 similar to rib 1452 and a head portion 1550 extending from the rib 1552. A thermoplastic resin element 1530 is spin friction welded into position. An annular recess 1555 in the head portion 1550 adjacent the lower end of the element 1530 receives molten resin and assists in the seal between the element 1530 and the post 17. The rib 1552 limits flow of molten resin through the aforesaid annular space.

In Fig. 16, a thermoplastic resin sleeve 1650 is inserted over the post 17 before the lid 23 is fitted into the box. The sleeve 1650 has a radially outwardly projecting annular flange 1659 which is of greater diameter than that of the aforesaid annular space.

The lid 23 is formed with a rib 1660 projecting downwrdly from the edge of the lip 29 surrounding the aforesaid annular space.

During the friction welding operation in which the lid 23 is secured to the box 11, the rib 1660 is friction welded to the flange 1659. In order to take up any tolerances, the lip 29 could be made flexible so as to avoid excessive pressures being applied to the sleeve 1650.

Alternatively, the sleeve 1650 is made a rela tively tight fit on the post 17 and located rather higher than necessary. During the friction welding operation, the rib 1660 urges the sleeve 1650 downwardly into the correct position. The sleeve 1650 is a sufficiently tight fit on the post 17 to ensure that sufficient frictional heat is generated to effect welding of the rib 1660 and flange 1659 together. In a further alternative, the flange 1659 is made sufficiently flexible to take any necessary tolerances. After the lid 23 has been fitted, a thermoplastic resin element 1630 is spin friction welded into position or is in situ injection moulded into the bore 28.

The terminal post 17 may have flats or splines extending completely along its length with corresponding flats or splines being provided internally of the sleeve 1650 so that rotation of the latter relative to the post 17 is prevented.

In the embodiments described herinabove in relation to Figs. 7 to 16, the aforesaid annular space (i.e. the space defined between the terminal post 17 and the lip 29) is of circular cross-section. It is to be appreciated, however, that this space need not be of circular cross-section, particularly in the case where the lid 23 is linearly reciprocated. The embodiments of Fig. 7, 10, 12, 14 and 15 and the in situ injection moulded embodiments of Figs. 9 and 16 may be used, mutatis mutandis, in such cases. In any of the in situ injection moulded embodiments described hereinabove, the bore 28 may be splined or of a non-circular cross-section (e.g. hexagonal) to ensure mechanical keying of the thermoplastic resin element within the bore 28 and to assist in ensuring unwanted rotation of the battery terminal in service under an applied torque. As in the case of the embodiment of Figs. 1 to 5, the bore 28, terminal post 17 and the spin friction inserted element of Figs.

9, 11, 13 or 16 may be tapered and the element may be ribbed on its outer surface with the surface of the post 17 roughened in the region of the bore 28.

In a further alternative embodiment, the space between the wall of the bore 28 and the terminal post 17 is sealed in the manner described with reference to Figs. 1 and 2 in co-pending British Patent Application No.

34974/74 (Serial No. 1,516,632) the contents of which are incorporated herein by reference.

In the above Patent Application lips, corresponding to the lips 29 described herein, are of a size to permit passage of the respective terminal posts therethrough during fitting of the lid but are sufficiently flexible to be urged into sealing engagement around the respective terminal posts when injection moulding of the thermoplastic bush takes place. As modified for the present invention, the lips are made of a size to accommodate the respective terminal posts and the subsequent relative movement between the lips and the term

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

tively tight fit on the post 17 and located rather higher than necessary. During the friction welding operation, the rib 1660 urges the sleeve 1650 downwardly into the correct position. The sleeve 1650 is a sufficiently tight fit on the post 17 to ensure that sufficient frictional heat is generated to effect welding of the rib 1660 and flange 1659 together. In a further alternative, the flange 1659 is made sufficiently flexible to take any necessary tolerances. After the lid 23 has been fitted, a thermoplastic resin element 1630 is spin friction welded into position or is in situ injection moulded into the bore 28.

The terminal post 17 may have flats or splines extending completely along its length with corresponding flats or splines being provided internally of the sleeve 1650 so that rotation of the latter relative to the post 17 is prevented.

In the embodiments described herinabove in relation to Figs. 7 to 16, the aforesaid annular space (i.e. the space defined between the terminal post 17 and the lip 29) is of circular cross-section. It is to be appreciated, however, that this space need not be of circular cross-section, particularly in the case where the lid 23 is linearly reciprocated. The embodiments of Fig. 7, 10, 12, 14 and 15 and the in situ injection moulded embodiments of Figs. 9 and 16 may be used, mutatis mutandis, in such cases. In any of the in situ injection moulded embodiments described hereinabove, the bore 28 may be splined or of a non-circular cross-section (e.g. hexagonal) to ensure mechanical keying of the thermoplastic resin element within the bore 28 and to assist in ensuring unwanted rotation of the battery terminal in service under an applied torque. As in the case of the embodiment of Figs. 1 to 5, the bore 28, terminal post 17 and the spin friction inserted element of Figs.

9, 11, 13 or 16 may be tapered and the element may be ribbed on its outer surface with the surface of the post 17 roughened in the region of the bore 28.

In a further alternative embodiment, the space between the wall of the bore 28 and the terminal post 17 is sealed in the manner described with reference to Figs. 1 and 2 in co-pending British Patent Application No.

34974/74 (Serial No. 1,516,632) the contents of which are incorporated herein by reference.

In the above Patent Application lips, corresponding to the lips 29 described herein, are of a size to permit passage of the respective terminal posts therethrough during fitting of the lid but are sufficiently flexible to be urged into sealing engagement around the respective terminal posts when injection moulding of the thermoplastic bush takes place. As modified for the present invention, the lips are made of a size to accommodate the respective terminal posts and the subsequent relative movement between the lips and the terminal posts during friction welding of the lid to the box whilst still being of a sufficiently flexible nature and size to seal against the terminal posts during the injection moulding of the thermoplastic resin elements. Such a lip construction may also alternatively be used with spin friction welded elements which, when inserted into the respective bores, urge the lips into sealing engagement with the terminal posts.

WHAT WE CLAIM IS:- 1. An electric storage battery including an open topped, thermoplastic resin battery box divided into cell compartments by partition walls integral with the box, packs of battery plates and separators located within the cell compartment, the electrical connections between battery plates in adjacent cell com apartments being made through the partition walls, a thermoplastic resin lid secured to the top peripheral edge of the box and the tops of the partition walls by friction welding, and a pair of terminals connected to battery plates in the end cell compartments respectively of the box and extending through respective apertures in the lid, each terminal member defining a space with the wall of its associated aperture and each space being at least partially filled by a thermoplastic resin element sep arate from the lid so that the aperture is sealed.
2. An electric storage battery including an open topped, thermoplastic resin battery box divided into cell compartments by partition walls integral with the box, packs of battery plates and separators located within the cell compartment, the electrical connections between battery plates in adjacent cell compartments being made through the partition walls, a thermoplastic resin lid secured to the top peripheral edge of the box and the tops of the partition walls by friction welding, and a pair of terminals connected to battery plates in the end cell compartments res pectively of the box and extending through respective external walls of the box.
3. A battery as claimed in claim 1, wherein each thermoplastic resin element is an element which has been in situ moulded in the respective aperture.
4. A battery as claimed in claim 1, wherein each thermoplastic resin element is an element which has been performed and then inserted into the respective aperture.
5. A battery as claimed in claim 4, wherein each thermoplastic resin element is an element which has been friction welded into the respective aperture.
6. A battery as claimed in claim 3, 4 or 5, wherrein a lower portion of a wall of each aperture extends in spaced relationship around the respective terminal, and means is provided for at least partially obscuring each space to

prevent or limit passage of thermoplastic resin from the element therethrough into the respective cell compartment.
7. A battery as claimed in claim 6, wherein each of said means is a sleeve surrounding a portion of the terminal disposed below said space.
8. A battery as claimed in claim 6, wherein each of said means is a sleeve surrounding a portion of the terminal disposed above said space.
9. A battery as claimed in claim 6, wherein each of said means is an element which is disposed in each space and which rests on a lip forming part of the wall of the respective apertures.
10. A battery as claimed in claim 6 when appended to claim 4 or 5, wherein each of said means is a rib extending from said element into the respective space.
11. A battery as claimed in claim 6, wherein each of said means is a rib extending around the terminal below the respective space, said rib being integral with the terminal.
12. A battery as claimed in claim 6, wherein each of said means is a rib on an electrically conductive sleeve on a portion of the respective terminal projecting externally of the lid.
13. A battery as claimed in claim 6, wherein each of said means is a thermoplastic resin rib, extending around the terminal below the respective space, friction welded to a rib extending integrally downwardly from a lip forming part of the wall of the respective aperture.
14. An electric storage battery substantially as hereinbefore described in Fig. 1 to 5 or Fig.

6 or in Fig. 1 to 5 as modified by any one of Figs. 7 to 16.
15. A method of manufacturing an electric storage battery comprisng the steps of.: - (a) starting with a thermoplastic resin, opentopped battery box having integral partition walls dividing the box into cell compartments in which packs of battery plates and separators are received, the required intercell connections being made through the partition walls, and a pair of terminal members being connected to respective sets of said battery plates in the end cell compartments respectively of the box and projecting beyond the top peripheral edge of the box, (b) pressing against the box a thermoplastic resin lid having a peripheral surface which engages the top peripheral edge of the box and rigs which, at their free ends, engage the tops of the partition walls, said terminal members extending through respective apertures in the lid with a space being defined between each terminal member and the wall of its associated aperture, (c) simultaneously with said step (b), imparting relative cyclic translatory move ment to the lid and the box in the plane of the open top of the box to frictionally heat, and thereby soften, the interengaging surfaces of the lid and the box, the space between the terminal members and the walls of their res pective apertures being sufficient to permit said movement, (d) ceasing said relative movement and pressing the lid onto the box to secure the lid to the box, and then (e) at least partially filling the space between each terminal member and the wall of its associated aperture with a thermoplastic resin element separate from the lid so that the element seals said apertures.
16. A method as claimed in claim 15, wherein each thermoplastic resin element is produced by injecting thermoplastic resin mat erial into the associated space.
17. A method as claimed in claim 15, wherein each thermoplastic resin element is produced by friction welding a preformed bush to the wall of the associated aperture.
18. A method as claimed in claim 16 or 17, wherein a lower portion of a wall of each aperture extends in spaced relationship around the respective terminal and each space formed thereby is at least partially obscured so as to prevent or restrict passage of thermoplastic resin from the element therethrough into the respective cell compartment.
19. A method as claimed in claim 18, wherein each space is at least partially obscured by providing a sleeve surrounding a portion of the respective terminal disposed below the space.
20. A method as claimed in claim 18 wherein each space is at least partially obscured by providing a sleeve surrounding a portion of the terminal disposed above said space.
21. A method as claimed in claim 18 wherein, each space is at least partially obscured by disposing therein an element which rests on a lip forming part of the wall of the respective aperture.
22. A method as claimed in claim 18.

when appended to claim 17, wherein each space is at least partially obscured by providing a rib extending around the respective element so that, when the latter is inserted into the respective aperture, the respective space is at least partially obscured by the rib before the thermoplastic resin flows as a result of the friction welding operation on the element.
23. A method as claimed in claim 18, wherein each space is at least partially obscured by providing each terminal with an integral rib disposed below the respective space.
24. A method as claimed in claim 18, wherein each space is at least partially obscured by providing a rib on an electrically conductive sleeve mounted on a portion of the respective terminal projecting externally of the lid.
25. A method as claimed in claim 18, each space is at least partially obscured by providing a thermoplastic resin rib extending around the terminal below the respective space, by providing a rib extending integrally downwardly from a lip forming part of the wall of the respective aperture, and by friction welding the two respective lips together during the friction welding of the lid to the box.
26. A method of manufacturing an electric storage battery comprising the steps of: (a) starting with a thermoplastic resin, opentopped battery box having integral partition walls dividing the box into sell compartments in which packs of battery plates and separators are received, the required intercell connections being made through the partition walls, and respective sets of said battery plates in each end cell compartment of the box being connected to a respective terminal member which terminates short of the open top of the box, (b) pressing against the box a thermoplastic resin lid having a peripheral surface which engages the top peripheral edge of the box and ribs which, at their free ends, engage the tops of the partition walls, (c) silmultaneously with step (b), imparting relative cyclic translatory movement to the lid and the box in a plane of the open top of the box to frictionally heat, and thereby soften, the engaging surfaces of the lid and the box, (d) ceasing said relative movement and pressing the lid onto the box to secure the lid to the box, and (e) before or after step (b), completing the terminals of the battery by connecting said terminal members through respective external walls of the box to further terminal members respectively located at the external surface of the box.
27. A method as claimed in claim 26 wherein each terminal member is resistance welded through a respective external wall of the box to its associated further terminal member.
28. A method as claimed in any one of claims 15 to 27, wherein the relative cyclic translatory movement imparted to the lid and the box in linear reciprocating movement.
29. A method as claimed in claim 28, wherein the partition walls extend parallel with each other and the linear reciprocating movement is in a direction parallel with the partition walls.
30. A method as claimed in claims 28 or 29 wherein the linear reciprocating movement has an amplitude between 0.1 and 0.25 inch.
31. A method as claimed in claim 29 or 20, wherein the linear reciprocating movement has an amplitude between 0.12 and 0.2 inch.
32. A method as claimed in any one of claims 15 to 27, wherein the relative cyclic translatory movement is angular reciprocating movement.
33. A method as claimed in ony one of claims 15 to 27, wherein the relative cyclic translatory movement follows a Lissajotis figure.
34. A method as claimed in any one of claims 15 to 33, wherein the pressure applied during step (b) is between 150 and 300 p.s.i.
35. A method as claimed in any one of claims 15 to 33 wherein the pressure applied during step (b) is between 200 and 250 p.s.i.
36. A method as claimed in any one of claims 15 to 35 wherein steps (b) and (c) are performed with the cell compartments containing the electrolyte of the finished battery, the box then being held stationary during step (c) while the required cyclic translatory movement is imparted to the lid.
37. A method as claimed in any one of claims 15 to 36 and including the further steps of positioning packs of battery plate grids, with said separators interposed therebetween, within said cell compartments, the grids carrying the battery paste require to produce said battery plates after conversion of the paste into the active material of the plates, and, after completion of the intercell connections, forming the grids within the box into said battery plates by converting the paste on the grids into the active materials of the plates.
38. A method as claimed in claim 17 or any one of claims 18 to 25 and 28 to 37 when appended to claim 17, wherein the wall of each aperture tapers inwardly towards the battery box, each terminal member tapers inwardly away from the battery box and each element is correspondingly tapered on its outer and inner surfaces so that, during the friction welding of the elements, resin at the outer and inner surfaces of the elements is melted.
39. A method as claimed in clairn 38, wherein each element has ribs at its outer surface.
40. A method as claimed in claim 38 or 39, wherein each element has ribs at its inner surface.
41. A method as claimed in claim 38, 39 or 40, wherein the surface of a portion of each terminal member engaged by the respective element is a rough surface.
42. A method as claimed in claim 15, 16 or 17, wherein a lip forming a lower portion of the wall of each aperture is made of sufficient size and flexibility to permit passage of the respective terminal member during pressing of the lid against the box to permit the relative movement between the wall of the aperture and the terminal member and to be flexed into sealing engagement around the terminal member by the thermoplastic resin element.
43. An electric storage battery when pro duced by the method as claimed in any one of claims 15 to 42.
44. A method of manufacturing an electric storage battery substantially as hereinbefore described with reference to Figs. 1 to 5, or Figs. 6 or Figs. 1 to 5 as modified by any one of Figs. 7 to 16 of the accompanying drawings.