This economizes, and prevents the waste of current. It is accomplished by connecting up the cells in such a manner that they may give a large voltage and small amperage, or a low voltage and great amperage, and in doing so will not detract from the efficiency of the battery.
Series and Parallel.—The device resorted to, whereby this may be accomplished, is in the manner that the cells are connected up with each other. In a general way, it may be said that the voltage has reference to the force, or pressure of the current, whereas amperage is the quantity which flows over the wire.
Each cell has a voltage of, approximately, one and a half volts, and it matters not how large the cell may be, the voltage is no more. The amperage, however, depends on the surface area of the plates comprising the active agents in the cell, so that each cell has, say one and a half volts, and ten, or twenty, or more amperes.
If a number of such cells are connected up in one way the output may be represented in high amperage, or in high voltage. If we have a certain number of cells, which, when combined, give ten volts and hundred amperes, the result would be 10 × 100, equal to 1000 Watts.
But they may also be so connected together that they will have an output of 100 amperes and 10 volts, the total of which is also 1000 Watts. Such a current would be put through the motor under ordinary running conditions, as a high driving power is not necessary.
But suppose it is desired to have a high or strong driving power; then the force of all the volts is required, so that one hundred volts are used, and only ten amperes.
The Connections.—This is brought about by connecting up the cells in series, or, in multiple or in parallel. The series connection is where the cells are placed in a row, for instance, and are connected together so that the carbon plate of one cell is joined by a wire with the zinc plate of the other cell; or the positive plate of one is connected with the negative plate of the other, and so on.
In that case all the current generated in all the cells join and flow along in one stream, from one end of the battery to the other. But now, all the positive plates may be connected together with one wire, and all the negative plates may be connected together with another wire, so that these two wires will thus be parallel with each other, and the lead wires which go to the motor are attached to these two parallel wires, and would represent the parallel type of connection.
But it is the most common practice to divide the cell into two sets, each of which is called a unit. Each unit, having a certain number of cells, can also have them connected up in series, or in parallel, and the different parallel units may be connected up together, so as to form a connection which is in multiple or in series multiple.
Suppose there are eight units, each of ten volts, the motor would receive eighty volts. But now, if the cells are in parallel, or in multiple, as the case may be, then the pressure at the motor is equal to that of a single unit, but the current flow is eight times that of the foregoing example.