Part 2 (1/2)

The jars which contain the plates, separators, and electrolyte are made of a tough, hard rubber compound. They are made either by the moulding process, or by wrapping sheets of rubber compound around metal mandrels. In either case the jar is subsequently vulcanized by careful heating at the correct temperature.

The battery manufacturers do not, as a rule, make their own jars, but have them made by the rubber companies who give the jars a high voltage test to detect any flaws, holes, or cracks which would subsequently cause a leak. The jars as received at the battery maker's factory are ready for use.

Across the bottom of the jar are several stiff ribs which extend up into the jar so as to provide a substantial support for the plates, and at the same time form several pockets below the plates in which the sediment resulting from shedding of active material from the plates acc.u.mulates.

Covers

No part of a battery is of greater importance than the hard rubber cell covers, from the viewpoint of the repairman as well as the manufacturer. The repairman is concerned chiefly with the methods of sealing the battery, and no part of his work requires greater skill than the work on the covers. The manufacturers have developed special constructions, their aims being to design the cover so as to facilitate the escape of gas which acc.u.mulates in the upper part of a cell during charge, to provide s.p.a.ce for expansion of the electrolyte as it becomes heated, to simplify inspection and filling with pure water, to make leak proof joints between the cover and the jar and between the cover and the lead posts which project through it, and to simplify the work of making repairs.

Single and Double Covers. Modern types of batteries have a single piece cover, the edges of which are made so as to form a slot or channel with the inside of the jar, into which is poured sealing compound to form a leak proof joint. This construction is ill.u.s.trated.

in Exide, Fig. 1.5; Vesta, Fig. 264; Philadelphia Diamond Grid, Fig.

256; U. S. L., Figs. 11 and 244; and Prest-0-Lite, Fig. 247, batteries. Exide batteries are also made with a double f.l.a.n.g.e cover, in which the top of the jar fits between the two f.l.a.n.g.es. In single covers, a comparatively small amount of sealing compound is used, and repair work is greatly simplified.

In the Eveready battery, Fig. 262, compound is poured over the entire cover instead of around the edges. This method requires a considerable amount of sealing compound.

The use of double covers is not as common as it was some years ago.

This construction makes use of two flat pieces of hard rubber. In such batteries a considerable amount of sealing compound is used. This compound is poured on top of the lower cover to seal the battery, the top cover serving to cover up the compound and brace the posts. Fig.

10 ill.u.s.trates this construction.

[Fig. 10 Cross-section of Gould double cover battery]

Sealing Around the Posts. Much variety is shown in the methods used to secure a leak proof joint between the posts and the cover. Several methods are used. One of these uses the sealing compound to make a tight joint. Another has lead bus.h.i.+ngs which are screwed up into the cover or moulded in the cover, the bus.h.i.+ngs being burned together with the post and cell connector. Another method has a threaded post, and uses a lead alloy nut with a rubber washer to make a tight joint.

Still another method forces a lead collar down over the post, and presses the cover down on a soft rubber gasket.

Using Sealing Compound. Some of the batteries which use sealing compound to make a tight joint between the cover and the post have a hard rubber bus.h.i.+ng shrunk over the post. This construction is used in Gould batteries, as shown in Fig. 10, and in the old Willard double cover batteries. The rubber bus.h.i.+ng is grooved horizontally to increase the length of the sealing surface.

[Fig. 11 U.S.L. cover]

Other batteries that use sealing compound around the posts have grooves or ”petticoats” cut directly in the post and have a well around the post into which the sealing compound is poured. This is the construction used in the old Philadelphia Diamond Grid battery, as shown in Fig. 254.

Using Lead Bus.h.i.+ngs. U. S. L. batteries have a f.l.a.n.g.ed lead bus.h.i.+ng which is moulded directly into the cover, as shown in Fig. 11. In a.s.sembling the battery, the cover is placed over the post, and the cell connector is burned to both post and bus.h.i.+ng.

[Fig. 12 Lead bus.h.i.+ng screwed into cover]

In older type U. S. L. batteries a bus.h.i.+ng was screwed up through the cover, and then burned to the post and cell connector.

An old type Prest-O-Lite battery used a lead bus.h.i.+ng which screwed up through the cover similarly to the U. S. L. batteries. Fig. 12 ill.u.s.trates this construction. The SJWN and SJRN Willard Batteries used a lead insert. See page 424.

The modern Vesta batteries use a soft rubber gasket under the cover, and force a lead collar over the post, which pushes the cover down on the gasket. The lead collar and post ”freeze” together and make an acid proof joint. See page 413. The Westinghouse battery uses a three part seal consisting of a lead washer which is placed around the post, a U shaped, soft gum washer which is placed between the post and cover, and a tapered lead sleeve, which presses the washer against the post and the cover. See page 417.

[Fig. 13 Cross section of old type Willard battery]

The Prest-O-Lite Peened Post Seal. All Prest-O-Lite batteries designated as types WHN, RHN, BHN and JFN, have a single moulded cover which is locked directly on to the posts. This is done by forcing a solid ring of lead from a portion of the post down into a chamfer in the top of the cover. This construction is ill.u.s.trated in Fig. 247.

Batteries Using Sealing Nuts. The Exide batteries have threaded posts.

A rubber gasket is placed under the cover on a shoulder on the post.