Fig. 91.-Sectional View of Geiszler Storage Battery for Ignition Ser

vice.

container jar of hard vulcanized rubber so they form a three cell combination that will deliver a current of about 6 volts and 60 amperes. A battery of this form is capable of being recharged when exhausted, as previously described.

Q. Name the principal parts of a typical storage battery. A. The various units of which the storage battery is composed are clearly outlined at Fig. 92. The main container is separated into three compartments by partitions moulded integral with the jar and which divide the main container into three distinct parts. The plate assembly is composed of either four or five plates made of lead alloy grids filled with various lead oxides. The plates are separated from each other by thin sheets of hard rubber, perforated with many holes for the passage of the electrolyte and a ribbed wooden separator is interposed between each pair of plates. When a five plate assembly is used, three of these are positive or collecting members, and two are negative or generating members. A five plate assembly has greater capacity than a four plate form, because both sides of the negative elements are exposed to the corresponding faces of positive plates.

The plate assembly becomes a unit because the various members are joined together by a bus bar of lead burned to the lugs projecting from the plates by means of the hydrogen flame. The top of the individual compartments are then closed with hard rubber cell covers in which vents to permit of the escape of the gases without danger of losing the liquid electrolyte from splashing are screwed. The three cells are then covered by one large cover which has a soft rubber gasket interposed between the jar and cover as a packing. Other forms of storage batteries have a compound of pitch, rosin, and other elements directly over the cell covers to effectively seal the elements in their respective compartments. The disadvantage of this method is that it is difficult to remove the plate assembly for repairs or cleaning, whereas the separate cover, which is held in place by numerous small screws, can be readily removed when it is necessary to gain access to the interior of the battery.

Q. What determines the capacity of a storage battery?

A. The capacity of a storage battery depends upon the size and nature of the plates used in each cell and their number as well as the number of cells joined together to form a battery. Batteries ordinarily used for ignition purposes are either of the 6 volt, 60 ampere, or 6 volt, 80 ampere type. Those used for lighting service

Fig. 92. Parts of Typical Storage Battery Used for Ignition Purposes. have larger plates and are more substantial in construction and are usually rated at 6 volts, 100 amperes and 6 volts, 120 amperes.

Q. What is meant by "discharge rate"?

A. A storage battery is designed so that it will deliver a certain amount of amperes over a given period of time. For instance, if the plates are light, the discharge of from 3 to 5 amperes should never be exceeded. This means that a 6 volt 60 ampere hour capacity battery would be able to discharge 3 amperes for 20 hours or 5 amperes for 12 hours before it would need recharging. The lighting batteries have much heavier plates and are constructed to stand larger discharge rates. In using a storage battery, it is imperative not to exceed the safe discharge rate given by the manufacturer.

Q. What would be the effect if the safe discharge rate was greatly exceeded?

A. If current was drawn from a battery faster than its discharge rate the battery plates will be injured. and will buckle and this results in loosening the active material from the grids and causes accumulations of sediment or "mud" in the bottom of the cell jars which might short circuit the battery.

Fig. 93.-Diagram Outlining Method of
Charging Storage Battery From Direct
Current, Using Lamp Resistance.

Q. How are storage batteries treated when exhausted?

A.

When storage batteries are exhausted they can only be restored to deliver more current by passing electrical energy through them from some external source.

Q. How are storage batteries charged from direct current?

A There are two methods of charging storage batteries from direct lighting circuits, one of which is outlined at Fig. 93, the other at Fig. 93-A. A storage battery should not be charged too fast because if attempt is made to rush the reforming of the plates by

passing large quantities of current through the cells, this will prove fully as disastrous as discharging the battery too rapidly. The manufacturers of various batteries recommend a certain normal charging rate, as well as a discharge rate.

A battery must a ways be charged longer than its rated capacity would indicate. For instance, if a charging rate of 5 amperes was recommended and a battery of 60 ampere hour capacity was to be restored to activity, it would take about 15 or 16 hours to charge it instead of the 12 hours one might think necessary if the total

capacity was divided by the charging rate. Storage batteries can be charged directly from 110 volt or 220 volt direct current lighting circuits by simply using a bank of lamps in series with the battery as indicated at Fig. 93 or a rheostat as shown at Fig. 93-A to regulate the number of amperes flowing into the battery. Then a bank of lamps is employed, either 16, 32 or 64 candle power bulbs may be utilized. A 16 candle power carbon filament lamp consumes about .5 of an ampere when used on 110 volt circuit. If it is desired to pass 3 amperes of current through the battery one can use six 16 candle power lamps in multiple or three 32 candle power; or one 64