EDISON'S STORAGE BATTERY.

Taranaki Daily News, Volume LIII, Issue 104, 10 August 1910, Page 3

EDISON'S STORAGE BATTERY.

To the Editor. Sir,—ln *h« issue of Thursday, July 28, you pu&lisbed some letters with reference to Mr- Edison's battery, and what it can db. The purpose of this letter ia to relate what it is. A storage cell or accumulator is a reversible galvanic couple —ii«. T a cell in wihich the electrical energy absorbed during 'the "charge" by chemical changes is partly returned on "di'sa&arge" by the reversal of these chemical changes. The only satisfactory cells- consist of electrodes, which are insoluble in the electrolyte, and the chemical compounds formed during the working of the cells must also he insoluble or practically insoluble, in the electrolyte, whether the electroyte takes an active part in the reaction or not. The field is accordingly narrowed down to the "lead" cell, the electrodes of which in the "charged" state are peroxide of lead at the "positive" pale and spongy or reduced led at the "negative" pole, the electrolyte beiiug dilute sulphuric acid, and to another type the development of which is but recent, namely the nickel-potash-iron cell, with which are associated the names of Jungner and Edison. A great deal of pains have heen devoted to developing the storage battery, with a view to reducing the weight which has hitherto been the great drawback to their use for electrictraction purposes. Mr. Edison act himself the task of finding a cell which should possess the following advantages: Absence of deterioration by work; large storage capacity per unity of mass; capability of berng Tapidly changed and discharged, inexpensiveness, and capable to withstand careless treatment. Some ten years ago Mr. Edison announced his invention of the nickel-iron- storage cell, and after severe tests was proved to withstand rough usage such as would be fatal to a lead eel!. However, it was not on the market long and was only heard of at intervals. But it has appeared again in an improved pattern and and under the auspices of the Edison Storage Battery Co., of Orange, .N.J. The present nickel-iron cell resembles its former, 'but for the positive plate, which has been modified. The battery is made in two sizes—type A 4 and type AB. The positive material in the positive plate consist of nickel oxide, and iron oxide is used in the negative electrode. The electrolyte consist of potassium hydrate to which is added a small amount of lithium hydrate. Graphite was used in the former cell, but in the new cell a substitute of pure nickel flakes electrochemically prepared are interspersed in the oxide to increase the conductivity of the active mass, because nickel oxide in itself is a poor conductor. The colls are made of electro-plated steel welded at the seems by the autogenous profeS9 —that is, by the application of the oxvacetylene Wow-pipe. The walls of the cells are corrugated, so as to obtain the greatest amount of strength with minimum weight. In an assembled battery each individual cell is held securely in place aind from contact with adjacent cells by means of small ebonite buttons fitting into indentations in the ' sides and bottom of the cell. In charging the cell the current ia sent into the positive pole and its attached negative, nickel . plate, through the electrolyte,, and into the positive plate of the iron compound which carries, the negative pole. The current deoxidises or reduces the compound to spongy metallic iron,, and carries the oxygen through the film of electrolyte to the nickel compound, oxidising it to the hyperoxide of nickel (N. 1.0.2), a higher oxide tihan the peroxide. On discharge, the current passes from the positive pole through the external circuit to the negative pole, and its attached iron or positive plate, and then through the solution to the negative or superoxide plate. In so doing, the oxygen moves back against the current, and partially reduces the nickel superoxide (.NW2) while oxidising spongy iron. The eir*rgy of burning of the iron and oxygen, which would be developed as heat mi the ordinary chemical process, is now liberated in the circuit as electrical ewiKV. The charging pulls the oxygen away' from the iron and delivers it tcmponiiily to the nickel. The condition is then stable until the circuit of-the cell i,« completed. Discharge then allows the oxygen to fall back from the pickel to the irdiTwith the natural affinity of iron and oxygen. On January 20th a tram car „|'» special type designed by Mr. R. W. Bench, and equipped with Edison batteries, was tested at West Orange, 'N.J., I ■with gratifying results. The body of 1 the ear is .IKft long, with -lit vestibule platforms-; the width is 7ft 3in., and has ii seating capacity for 2G. Light steel wheels are mounted on -2>/ 2 in diameter

steel axles, cue* of which is divided in the centre and provided with a steel ( sleeve, to iK'.rmit the free rotation of i each wheel independently of its mate. | Tli(! trunk is of the. standard crage, fourwheel fvpo, with Ofin fiin wheel hase. Tin; hod'y of the car weighs 35001b. the ■ truck and electrical equipment 35001b, mid the battery 30001b, giving a complete enr of 10,00011).' The car is driven by I two 5-h.p. motors and connected to the | wheels .by a .silent chain drive. During the test'it was found that the motors <r., vo the car a maximum speed of 15 miles per hour, and with 14 stops per mile, enabled a schedule of 8 miles per hour to he maintained. Much could bo said as to tho suitableness of this form of electric, traction for New Plymouth, but «s there is an expert at present at work to report on the tramway scheme, [ shall content myself to await his report before offering any comments.—l ),"„, oU-'., ' ELFXTIiTC POWER.