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Page 296

| Construction |

| The essential parts of a storage battery are the positive and negative plates, the separators, the electrolyte, and the container. In all types of batteries, the plates are made in the form of grids, which have two functions: (1) they serve as a support for the active materials since these are usually not self-supporting; and (2) they serve as a conductor to transmit current between the plate terminal and all parts of the active material. For both purposes, the form and dimensions of the plates should not change materially during the life of the battery. |

| Lead Battery |

| Plates. Since plates made of pure lead have little mechanical strength, they are alloyed with a small amount of antimony or calcium (Fig. 15-5). The alloy is formed into a grid whose slots may have rectangular, circular or diamond shapes. Lead peroxide is placed in the slots for plates and sponge lead for negative plates. |

| In the so-called iron-clad plate construction (Fig. 15-6), the positive plates consist of vertical parallel spines or shafts. Made of an antimony-lead alloy, these spines or shafts are attached to the horizontal top and bottom sides of the lead alloy frame. Cylinders of the active material are placed around them and held together by hard rubber tubes. The tubes are horizontally slotted to give the electrolyte access to the active material. The negative plates are essentially the same as other imbedded or pasted plates. |

| Figure 15-5 Lead cell. |

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