Such an arrangement is not only more compact than one having the elements composing each cell mounted upon separate strips, but will be found very convenient when an electrolyte composed of bichromate of potash and acid is used, because all the elements may then be raised out of the solutions at the same time.
It is possible to place the jars in a frame and arrange a windlass fitted with a crank so that the elements may be easily raised or lowered from and to the solution. Such an arrangement is called a "plunge battery."
Connecting Cells.
Cells may be connected either in *series*, in *multiple*, or in *series-multiple*, depending upon the number of cells to be used and the amperage and voltage desired.
[Illustration: FIG. 33.—Showing how Cells are arranged when they are connected in Series. The Voltage of Six Dry Cells connected in series as above would be approximately 6 x 1.5 or 9 Volts.]
Cells are in series when they are connected with a wire leading from the negative pole of one of the positive pole of another, so that the current flows through each one in turn. Figure 33 shows six cells connected in series. Cells are placed in series when voltage is the most important factor. The total voltage of the battery is then equal to the sum of the voltages of the cells. For example, the voltage of the ordinary dry cell is about 1.5 and therefore if four dry cells are connected in series the total voltage of the battery will be six. If six dry cells are connected in series the voltage at the terminals will be about nine.
When a heavy amperage is desired, cells are connected in multiple. Figure 34 shows six cells connected in multiple. It will be noticed that all the negative poles are connected together to form one terminal, while all the positive poles form another. The amperage of the average dry cell is about 20. The amperage of a battery of cells connected in multiple is equal to the sum of the amperages of the separate cells. The amperage of four cells connected in multiple will be about 80 and about 120 in the case of six cells.
[Illustration: FIG. 34.—Showing Six Dry Cells connected in Multiple. The
Voltage of such an arrangement would only be 1.5, but the Amperage
available would be six times that possible from Cells connected as in
Figure 33.]
The life of the average dry cell is about twenty ampere hours under normal conditions. If however the cell is discharged at a high rate, say for instance, five amperes, it will be found that the life is less than twenty ampere hours. On the other hand, if the discharge rate is very low, as for example, one-quarter of an ampere, the capacity of the cell will be greater. In order to get the most economical service from a battery it is therefore advisable to lighten the load as far as possible, and cells are consequently often connected in *series-multiple* with that result in view. In a case, for illustration, where it might be desirable to secure a current 4 1/2 volts and five amperes from dry cells, the series-multiple arrangement could be recommended. Three dry cells connected in series will furnish 4 1/2 volts and five amperes, but by using two sets as in Figure 35, the load is divided between them and each set will only have to furnish amperes to the circuit. *Two sets of cells used in series-multiple will therefore last more than twice as long as either set would alone.*
The series-multiple arrangement is recommended where cells are to be used for operating toy trains, induction coils, motors, etc., as being the most economical.