Battery construction.

When starting and lighting systems were adopted in 1912, storage batteries had been used for many

years in electric power stations. These were however large and heavy and many difficult problems of

design had to be solved in order to produce a battery capable of performing the work of cranking a car

engine. It must be able to do its work quickly at all times, in all sorts of weather, with temperatures

ranging from below 0° to 100° Fahrenheit, or even higher. Thus, the starting and lighting battery has

been designed to withstand severe operating conditions. Bars of lead connects the posts of one cell to

those of the next. At the centre of each cell is a removable rubber plug covering an opening through

which communication is established with the inside of the cell for the purpose of pouring in water,

removing some of the electrolyte to determine the condition of the battery, or to allow gases formed

within the cell to escape.

Insert fig 3

If the lead bars should be removed, connecting one cell to another, we should find that the posts

which project out of the cells are attached to the plates which are broad and flat, and separated by thin

pieces of wood or rubber. If we lift out the plates we will find that they are connected alternatively to

the two lead posts, and that the two outside have a grey colour. Pouring out the electrolyte we find

several ridges which hold the plates off the bottom of the jar. The pockets formed by these ridges may

contain some soft, muddy substance, thus we have exposed all the elements of a cell; posts, plates,

‘separators’ and electrolyte. The grey coloured plates are attached to the ‘negative’ battery post, the

chocolate- brown to the ‘positive’ battery post.

Plates.

A starting and lighting battery consists of the following principal parts:

1. Plates 4. Jars

2. Separators 5. Covers

3. Electrolyte. 6. Cell connectors and terminals. 7. Case.

Casting the Grid.

‘Pasted’ plates is the universal plate of automobiles, the grid is the skeleton of the plate. It performs

the double function of supporting the mechanically weak active material of conducting the current. It

is made of lead antimony alloy which is melted and poured into a mould. Pure lead is too soft and too

easily attached by the electrolyte, and antimony is added to give stiffness and resistance to the action

of the electrolyte in the cell. The amount of antimony used varies in different makes but probably

averages 8 to 10%. The casting process requires considerable skill, the proper composition of the metal

and the temperature of both metal and moulds being of great importance in securing perfect grids

which are free from blowholes, and which have a uniform structure and composition. Some

manufacturers cast two grids simultaneously in each mould, the two plates being joined to each other

along the bottom edge.

Trimming the grids.

When the castings have cooled they are removed from the moulds and passed to a press or trimming

machine which off the casting gate and rough edges. The grids are given a rigind inspection, those

having shrunken or missing ribs or other defects being rejected. The grids are now ready for pasting.

(note; insert Fig 4. here)

Fig 4. shows a grid ready for pasting. The heavy lug at one upper corner is the conducting lug, for

carrying the current to the strap into which the lugs are burned when the battery is assembled. The

vertical ribs of the grids extend through the plate, providing mechanical strength and conductivity

while the small horizontal ribs are at the surface and in staggered relation on opposite faces. Both the

outside frames and the vertical ribs are reinforced near the lug, where the greater amount of current

must be carried.

The rectangular arrangement of ribs, as shown in Fig. 4. is most generally used, although there are

other arrangements such as the Philadelphia ‘Diamond’ grid, in which the ribs form acute angles,

giving diamond shaped openings.