GB2146833A

GB2146833A - Storage batteries

Info

Publication number: GB2146833A
Application number: GB08325093A
Authority: GB
Inventors: Guy Donald Negus
Original assignee: NEGUS DONALD GEORGE; NEGUS ROBIN HENRY
Current assignee: NEGUS DONALD GEORGE; NEGUS ROBIN HENRY
Priority date: 1983-09-20
Filing date: 1983-09-20
Publication date: 1985-04-24
Also published as: GB8325093D0

Abstract

The invention relates to a method of manufacturing a storage battery having a container 10 subdivided by partition walls 14 into individual cells and a lid 12 designed to be heat welded to the container 10 and to seal each cell. The method comprises the steps of forming cut-outs 16 in the partition walls 14 for receiving links 18 interconnecting the plate straps of adjacent cells, mounting the plates of the accumulator in the respective cells, sealing by means of a viscous epoxy resin around the links 18 connecting the plates of adjacent cell, applying a viscous epoxy resin to the lid around the contour of the container, fitting the lid to the container and allowing the epoxy resin to cure. <IMAGE>

Description

SPECIFICATION Storage batteries The present invention relation to the manufacture of storage batteries such as lead-acid accumulators.

A knows method forforming the casing of a lead acid accumulatorcomprisesforming a container divided into individual cells and a lid which fits over the top of the container. ltisnecessaryforthelidto seal the container both to isolate the cells from one another and to prevent leakage of acid from the battery. ln orderto achieve this, the lid isformed with ribs on its under-surface which define continuous channels following the same contour as the cross section of the-c 3ntainer.

To assemblesuch a casing,the channels are filled with a flowing epoxy resin while the lid is inverted and the container, with the constituents of the battery arranged within it, is placed upside down overthe lid and left in position until the epoxy resin sets.

When securing the lid to the container, it is not only necessary to seal between the lid and the container but also around links which interconnectthe cells and pass overthe partitions between individual cells. It is necessary to use any epoxy resin which flows quite readily in orderto seal around these links and it is for this reason that it is essentialto provide channels in the lid to contain the epoxy resin prior to its being cured as it would otherwise flow indiscriminately.

Though this method of manufacture is commonly used it does not readily lend itself to mass production and more recently instead of using any epoxy resin, the lid is welded to the container by first heating the lid and the upper edge ofthe container and pressing the two firmly together to form a weld. With a casing intended for assembly by welding, no channels are provided for the epoxy resin and instead projections are formed on the lid to help centre it correctly on the container.

The disadvantage nowfound with containers designed for assemblybywelding is that the cost of the equipment to weld the lid to the container can only be justified when batteries are to be manufactured in large quantitiesandthis precludes the production by smaller manufacturers of certain sizes for which the demand is notvery great. Furthermore,thewelding apparatus must be changed whenever a different size of battery is to be made and the changeover may not bewarrantedforsmallerproduction runs.

The present invention seeks to provide a method of manufacturing storage batteries using casings designed for heat welding but which overcome the need for expensive welding equipment so as to render smaller production runs commercially viable.

In accordance with the present invention, there is provided a method of manufacturing a storage battery having a container subdivided by partition walls into individual cells and a lid designed to be heat welded to the container and to seal each cell, the method comprising forming cut-outs in the partition walls for receiving links interconnecting the plates in adjacent cells, mounting the plates ofthe accumulator in the respective cells, sealing by means of a viscous epoxy resin around the links connecting the plates of adjacent cell, applying a viscous epoxy resin to the lid around the contour of the container, fitting the lid to the container and allowing the epoxy resin to cure.

Because the lid of a casing designed to be welded is formed with locating pips to centre it on the container it is possible to determine accurately where the viscous epoxy resin should be applied. There is however no need for channels as the epoxy resin is sufficiently viscous to prevent it from flowing during the inversion of the lid for assembly ofthe casing.

It is preferable to heat treat the plastics material priortothe application of an epoxy resin in orderto achieve proper adhesion. Such heattreatment may comprise passing a flame over the mating surfaces of the lid and the container.

The invention thus proposes the use of a thick epoxy resin to assemble casings not designed for the purpose and because of the viscosity of the epoxy resin which must be used to prevent it from flowing during the assembly stage the sealing of the link passing overthe partitions must be performed prior to the placing of the lid overthe container.

The invention will now be described further, byway of example, with reference to the accompanying drawings, in which the single figure is a perspective view partly cut away showing parts of a lead-acid accumulator.

In the accompanying drawing, the container of a lead acid accumulator is designated 10 and has a lid 12. The container 10 is divided into several cells by partition walls 14 and within each cell there is placed the conventional arrangement of plates. This arrangement comprises several positive and negative plates spaced from one another by separators, the negative plates being connected to one another by a negative plate strap and the positive plates being separately connected to one another by means of a positive plate strap.

The straps of adjacent cells must be connected to one another in order to connectthe cells in series (or in parallel) and this has in the past been achieved in a variety of ways. At one time the interconnection was carried out externally and each cell had a pair of posts projecting through the lid and the posts of adjacent cells were interconnected by means of external links.

More recently, however, the interconnections were carried out internally and in the case of a container intended to be assembled by means of an epoxy resin the links merely passed overthe upper ends ofthe partition walls and fitted within the channel in the lid in which the epoxy resin was poured. This method cannot however be used in the present invention as it is no longer possible to use an epoxy resin capable of flowing readily.

With container design for heat welding, the interconnection of the straps of adjacent cells was performed bya link passing directlythroughthe partition and heatwelded into position but once again this requires expensive equipment.

To mitigate this problem, cutout 16 arefirstformed in the partition walls 14to receive over-partition links 18 bridging the straps of adjacent cells. The seal around the links 18 pieces is performed by using an epoxy resin which is sufficiently viscous to remain in position while curing, to seal the space between the link 18 and the cut out 16.

The lid 12 as seen in the drawing has on its lower side projecting pips 20 which act as guides for centring the lid 12 overthe container 10 during the intended welding operation. These pips 20, in the method of manufacture ofthe invention, serve as guides for positioning oftheepoxy resin and enable the epoxy resin to be placed so as to overlie accuratelythe contour of the container when assembled. Afterthe epoxy resin has been spread overthe lid 12, the lid 12 is inverted and positioned overthe container 10 and the epoxy resin is allowed to curewhile pressure is applied to the lid 12 to keep it in position. Aftercuring ofthe epoxy resin, the terminal posts 22 of the first and last cells are soldered to lead inserts in the lid 12 in the usual manner.

It can thus be seen thatthe invention enables a lid and container specifically designed by welding to be employed in assembly by use of an epoxy resin which method is more readily suited to smaller production runs and can be implemented withoutthe use of expensive equipment.

Claims

1. A method of manufacturing a storage battery having a container subdivided by partition walls into individual cells and a lid designed to be heat welded to the container and to seal each cell, the method comprising forming cut-outs in the partition walls for receiving links interconnecting the plates in adjacent cells, mounting the plates ofthe accumulator in the respective cells, sealing by means of a viscous epoxy resin around the links connecting the plates of adjacent cell, applying a viscous epoxy resin to the lid around the contour of the container, fitting the lid to the container and allowing the epoxy resinto cure.

2. A method as claimed in claim 1 wherein the material of the lid and the container is heattreated priortothe application ofthe epoxy resin, in orderto improve adhesion.

3. A method of manufacturing a storage battery, substantially as herein described with reference to and as illustrated in the accompanying drawing.