1901 Automobile Club Show
Held at the Agricultural Hall, Islington.
ELECTRICITY AT THE AUTOMOBILE CLUB EXHIBITION. [4]
A very important departure on the commercial side, confined to electrical cars, is that of the City and Suburban Electric Car Co, of Denman Street, Piccadilly, who are laying themselves out to maintain the cars in a thoroughly convenient manner to the owners, where the cars are purchased from them. They propose to house, clean, insure, and look after the cars generally, so that they can be taken out at any time of the day or night, and to provide an unlimited supply of charging current for a fixed annual or quarterly rental.
The cars will be run round to the house of the owner immediately on receipt of a telephone message, and will be run back to the station when the owner alights, fresh accumulators put in, or fresh charge, as may be necessary. In the case of the theatre, the cars will not wait outside the theatre; the station will have notice when the piece is nearly over, and the car will be run round, or it can be had by telephone at any time. The charge is uniform for all sizes of vehicles and for all classes of users. The company propose to open depots wherever trade allows.
There was very little new in the matter of electrical ignition. Messrs. Peto and Radford exhibited the celluloid accumulator which was illustrated in The Autocar three weeks since. Its special features are, the plates rest in sort of celluloid comb which keeps them apart, but allows the inside to be seen between the plates. There is also a vent of a special form, which prevents the liquid from splashing out.
The Meyra Co exhibited their battery running a small incandescent lamp, which is about as severe a test as a battery of that kind could have — much more severe than the actual work it will be called upon to do on the car.
The Doe Battery Co showed their battery running a coil giving a 0.25in. spark, fairly fat, which is also a severe test for continuous work, so far as the battery is concerned.
Messrs. Peto and Radford exhibited a very compact case of large salammoniac cells for charging accumulators, which will be very handy where there is no convenient supply, or if there is any trouble in applying it.
Mr. H. W. van Raden, of Coventry, exhibited samples of his patent woven glass accumulators, the special feature of which is the employment of woven or spun glass in their manufacture. Readers of The Autocar will be familiar with the fact that glass can be drawn into a very beautiful silk-like thread, which can be, and is, used for a variety of purposes, principally for ornamentation. Mr. van Raden uses it for the double purpose of keeping the active material (the oxides of lead) in its place, and for separating the plates, preventing the oxides from making short circuits between the plates if any fall out. These two points are the most difficult to deal with in accumulator work. All sorts of devices are employed for the purpose of preventing the oxides, principally the oxide on the positive plate, from falling out or scaling off its plate, being shed, as the Americans expressively term it, and various other devices are employed to keep the plates sufficiently apart, so that if a piece of oxide does fall out it cannot make connection between the plates, and to prevent the plates themselves from coming into contact by buckling. In the process of charging and discharging, the active material undergoes large changes of volume, sometimes carrying the supporting plates with it; hence the precautions necessary.
In Mr. van Raden's cell the oxides are woven in with the glass thread, the woven mass forming the finished plate, and in addition a sort of pad of the glass thread or fluff is wrapped round each plate to keep them apart. It will be understood that the woven glass, even when in the form of a cloth, is very porous, just as any cloth is, so that the electrolyte has full opportunity to pass through the pores. Mr. van Raden claims that in consequence of the method he adopts of using the glass thread or woven glass he obtains a lighter cell and one with smaller resistance with a given size.
Mr. van Raden also makes small dynamos giving fifteen volts and twenty volts, for charging small accumulators, and he showed some very neat arrangements for adjusting the resistance in circuit with the cells when charging (what electricians call rheostats) with measuring instruments and switches mounted together on one hoard.
Mr. van Raden claims that he can charge his cells in three hours with perfect safety, and even in one hour if a low efficiency — a low return of the energy put into the battery — can be allowed. He prefers six to seven hours.
Mr. van Raden doubtless fully believes that his spun silk offers a lower resistance than other methods of separation, but it is at least open to doubt whether he is correct. With the ordinary method of separation of the plates, the liquid itself is the only substance between them, and consequently the resistance of the liquid is measured simply by the distance between the plates, divided by the dimensions of the plates. With Mr. van Raden's arrangement only a smaller portion of liquid is interposed between the plates, only that in the pores of the spun glass taking part in the electrical action, so that the interposition of the porous division is equivalent to increasing the resistance, unless the plates are brought nearer together to an equivalent amount, and there is then the possibility of the active material forcing its way through the meshes of the spun glass. The case is one for measurement and practical experience, but is of far less importance than reliability and durability, both of which points are undoubtedly secured.