Thus, to connect the positive pole of the charging generator with the negative pole of the storage battery would reverse the current and quickly destroy the plates.
Time Required, and Current.—It requires time to charge a battery, usually from twenty to thirty hours. The usual charging rate is about fifty amperes for a cell with a capacity of forty ampere hours, and the voltage should be somewhat higher than the normal voltage output designed for the battery when it is in action.
Troubles in Use.—The most frequent trouble in the use of batteries comes from short circuiting. This arises from two causes. The grids of the batteries are made of lead, cast in the form of flat plates, having small interstices, or openings, which are filled with various preparations, principally peroxide of lead.
Other types use iron and nickel, and many are composed of lead and zinc, but in any case the object of the grid is to receive and hold the active material, and present as large a surface of the minum as possible to the action of the electrolyte.
When in use the lead particles begin to disintegrate, more or less, and fall out of the cavities of the grid, dropping to the bottom of the cell. In time the material thus deposited will form a path between the two adjoining plates, producing what is called a short-circuit, and if the accumulation is not removed, the plates will be seriously injured.
Overcharging.—Sometimes the plates are overcharged, and the result is they will buckle, so that they touch each other, and a short circuit results. These hints are usually sufficient to indicate where the trouble will be found if the current measuring instruments indicate an excessive flow of current. In such cases the first direction to which the examiner turns is the battery.
The Circuiting.—It has been found necessary, in providing for the operations of an electric vehicle, that the motor should have a means whereby the speed and power of its output can be regulated.
This may seem a very simple matter, at first glance, because, without stopping to examine the problem, and all the elements involved, it would be easy to settle it by simply giving the motor more or less current. To do so would turn the motor faster or slower.
In the gasoline car provision is made whereby, through the change speed gears, the engine gets the benefit of the leverage, by reducing the speed of the axle, relative to the engine shaft, at first speed, and this enables the motor to pull the car up steep grades, or over difficult roads, which it would not be able to do if the relative rotations were the same as at high speed.
Economy in Use of Current.—The same thing is necessary in the operation of the electric motor. The current must be so arranged that at certain periods it will be more effective than at others, and this effectiveness is generally wanted at times when the axles turn very slow, just the same as with the gasoline car.