Electrical connection of the terminal posts of a lead-acid battery to the exterior.

The present invention refers to the electrical connection of the battery posts to the exterior.

More particularly the present invention refers to the electrical connection to the exterior of a valve regulated lead-acid battery with internal gas recombination. It is well-know that, with valve regulated lead-acid batteries with internal gas recombination, one of the principal technical problems is obtaining good, econo­mical electrical connection of the posts to the exterior.

The problem consists in how to make the metallic electrical connection through the cover, generally made of plastics, and how to make said metallic connection and the plastic material of the cover remain permanently sealed against possible seepage of the sulphuric acid electrolyte towards the exterior. The tightness of this seal becomes all-important in the case of lead-acid batteries with internal gas recombination. With such batteries, in fact, it is necessary not only to prevent any leakage of electrolyte towards the exterior but also to have a sufficient seal against any possible intake of air (and thus of oxygen) from outside in case of a negative internal pressure, in order to avoid rapid deterioration of the battery.

Various solutions to the problem have been proposed, some of which are shown in schematic form in Figures 1-3. In particular, one known solution consists of threading on to the battery posts, which have the form of short rods which project through two suitable holes in the cover, two special rubber sealing rings (O-rings) which allow, upon gluing of the cover to the battery, the exit holes of the posts (to which the tabs will have been soldered) to be sealed with an appropriate resin. Two examples of this kind of connection and its corresponding sealing are shown in Figures 1 & 2. This solution is simple, but rather costly owing to the use of O-rings and of the labour to place them. Another solution is illustrated in Fig. 3, whereby the battery is closed by sealing on a cover which originally has no exit holes for the posts which have a flat shape. This operation is performed with both cover and battery upside down. After the sealing resin has set, two holes are drilled in the cover until they reach the underlying terminals. The tabs are then soldered on to the tops of the posts, and the sealing is completed by pouring sealing resin round the tabs themselves. This method, while avoiding the higher costs due to the use of O-rings, makes the soldering difficult and rather weak as it has to be done on the head under the cover and thus practically inside the battery. The object of the present invention is to make an improved connection with the exterior of the terminal posts in valve regulated, internal gas recombination lead-acid batteries.

More particularly, the object of the present invention is to produce a connection of the above type which makes it easier to connect the terminals posts to the tabs and to eliminate the disadvantages of known types of connection and to obtain more certain, more effective and more economical connections and seals.

According to the present invention these and other objectives which will be revealed in the following descriptions are to be achieved by an electrical connection obtained by placing upside down, on an inverted cover provided with blind housings for the terminal posts and filled with an adherent resin, a battery provided with short rod-shaped posts; uprighting the whole when the resin has solidified, removing the external part of each housing and the resin it contains until the terminal posts are exposed and then connecting the tabs to each post.

This connection may be carried out by soldering, which can be further protected by additional application of resin from outside.

The essential features of the electrical connection according to the present invention which allow improvement of the conditions of both connection and sealing are effectively two, namely: <ul id="ul0001" list-style="none"><li>1. The use of rod-shaped posts, and</li><li>2. The provision of two housings in the battery cover, initially blind and without holes leading to the exterior, and within which the rod-shaped terminal posts are placed during the phase of sealing on the cover with adhesive resin.</li></ul>

Once the rods have been freed of the solidified sealing resin it is possible to connect the tabs very easily, preferably by soldering them on from outside and then to seal this connection with resin. For better understanding of the electrical connection according to the present invention and the way in which it is to be obtained, these points will now be described in detail making reference to Figures 4A to 4H (attached), which show the various work phases schematically.

For convenience the sequence makes reference to only one terminal post, but it is obvious that the same succession applies to both battery posts.

Referring to the sketches, the battery cover (1), which is provided with a housing (2) for the post (4), is placed puside down, the housing is filled with liquid sealing resin (3) and the battery is inverted and inserted.

After these operations (phase A, B &amp; C), each post (4) will be immersed in the resin within the housing.

Once the resin has solidified the battery and its sealed on cover (1) is uprighted (phase D). Then, with a suitable tool (5) the outer part of the housing is milled away, removing the resin until the terminal post (4) is bared (phase E).

The connecting tab (6), provided with a suitable eyelet (phase F), is slipped over the terminal pole (4), which has been freed from the solidified resin (3), so that the tab projects from the cover of the battery. The tab is then soldered (7) on to the post (phase G), and the joint is sealed off externally with resin(8) (phase H). As this stage, since the desired connection of the post with the exterior has been produced, the battery is ready to be finished by filling it with the electrolite, setting the valves and finally closing the battery with the top lid (9).