Watts.—This brings in another element that should be understood. If the current is multiplied by the amperes a factor is obtained, called Watts. Thus, as each cell has 11/2 volts and 25 amperes, their product is 371/2 watts.
To show that the same energy is present in each form of connection let us compare the watts derived from each:
Series connection: 9 volts × 25 amperes, equal 225 watts.
Parallel connection: 11/2 volts × 150 amperes, equal 225 watts.
Series Multiple connection: 41/2 volts × 50 amperes, equal 225 watts.
From the foregoing, it will be seen that the changes in the wiring did not affect the output, but it enables the user of the current to effect such changes that he may, for instance, in case a battery should be weak, or have but little voltage, so change connections as to temporarily increase it, although in doing so it is at the expense of the amperage, which is correspondingly decreased.
It would be well to study the foregoing comparative analysis of the three forms of connections, so far as the energy is concerned, because there is an impression that increasing the voltage, is adding to the power of a current. It does nothing but increase the pressure. There is not one particle of increase in the energy by so doing.
Testing a Cell.—The cells should be frequently tested, to show what loss there is in the amperage. This is done by putting an ammeter in the circuit. If a meter of this kind is not handy, a good plan is to take off one of the wire connections, and snap the wire on the terminal, and the character of the spark will show what energy there is in the cell.