Edison pioneered the invention and development of the nickel-iron battery in the early years of the 20th century.
Electric Lighting (Crocker, 1904)
The book Electric Lighting written by Francis Crocker in 1904 contains a detailed description of the Edison battery as it had developed to that time.
The standard cells of this type are 13 inches high, 5.1 inches wide, and vary in length according to their rating, the various capacities being obtained by simply increasing the number of plates. The positive and negative plates are alike in appearance, and consist of rectangular grids, of nickel-plated iron, each about 9 1/2 by 5 by .025 inch, punched with three rows of rectangular holes, eight holes to the row (Fig. 168); each hole being filled by a shallow perforated box of nickel-plated steel, the perforations being very fine, about 2,500 per square inch. The difference between the positive and negative plates is entirely in the contents of the perforated receptacles; those for the positive plate containing a mixture of oxide of nickel and pulverized carbon, the latter being employed to increase the conductivity of the active material. The receptacles for the negative plates contain a finely divided oxide of iron and pulverized carbon. When filled these receptacles are secured to the grid by placing them in the openings of the same, and subjecting the assembled plate to a pressure of about 100 tons, which expands the pockets and fixes them firmly in the grid, the assembled plates being shown in Fig. 169. The liquid employed consists of a 20 per cent solution of caustic potash, which undergoes no chemical change during the process of charge or discharge, acting simply as a conveyor of oxygen between the plates. The charging current, entering at the positive plates, oxidizes the nickel compound to the peroxide state, and reduces the iron compound in the negative plates to a spongy iron mass. The containing vessel consists of nickel-plated steel, and the plates are strong individually and close together, being separated by thin strips of vulcanized rubber, thus forming a compact mass. The terminals of the plate pass through the cover of the cell, from which they are insulated by vulcanized rubber bushings. The electrical features of the Edison cell are as follows:— Average voltage of charge at normal rate, 1.68. Average voltage of discharge at normal rate, 1.24. A set of charge and discharge curves of a 180-ampere-hour cell is shown in Fig. 170. This battery is rated at 30 amperes for a period of six hours. The various cells have a weight efficiency of 11.5 to 13.2 watt-hours per pound, depending upon the size. The watt efficiency under normal working conditions is about 60 per cent. The charging and discharging rates are alike and cover wide ranges. A cell may be charged at a high rate in one hour, without apparent detriment except lowering the efficiency slightly. It is not appreciably influenced by temperature changes, and may be fully discharged to the zero-point of E.M.F., or even charged in the reverse direction, and then recharged to normal conditions without suffering loss in storage capacity or other injury. The best results are obtained when twice as many positive as negative plates are employed, and the standard cells are made up on this basis. This type is intended especially for electric automobile service, by virtue of its high weight efficiency, and ability to endure rough mechanical as well as electrical treatment. The same qualities would also adapt it to portable electric-lighting purposes.
Alkaline Battery 1906 (827279)
The patent drawing for Edison's 1906 Alkaline Battery (827279).
Storage Battery Electrode Plate 1906 (831269)
The patent drawings for Edison's 1906 storage battery electrode plates (831269).
Self-Heated Insulated Battery Box 1918 (1266780)
The following is describes normal maintenance of the Edison battery when used to power an electric vehicle.
In charging, however, the battery compartment must be left wide open. The small amount of electrolyte and the liability of heating on charge at the high charging rates which are permissible, give rise to an other sensitive point in the handling of this type of cell, namely, "low electrolyte," i . e., exposing the tops of the cells, and causing loss of storage capacity. In active service it is necessary to "fill up for evaporation" every few days, using distilled water only (ordinary water, which is more or less impure or which has been aerated by absorption of carbonic acid from exposure to the air, being injurious to the cell) , and putting in the water just before giving a charge, to avoid the false level due to gas bubbles in the electrolyte. Since the closed and sealed top of the cell prevents a view of its contents, a special filler is provided by means of which water may be added to the same height in a large number of cells in rapid succession. This filler is connected by a flexible rubber tube to an overhead covered tank of distilled water, and is also wired to an electric bell and dry battery. The filler spout is inserted in the aperture of the cell, and a thumb-valve on the filler is operated to allow the water to flow into the can. The stream of distilled water presents a high resistance in the bell circuit, but when the level of the electrolyte has risen into contact with the end of the spout, the bell rings. It is important to avoid filling the cans too full, for this leaves no room for the gas to escape during charge and the electrolyte is liable to be forced out in bubbles-a cause of low electrolyte.
The potash solution becomes contaminated in time, from impurities that have accidentally gotten into the cell either directly or by way of the filler spout (which may be laid down carelessly on a dirty bench) , or by absorption of gases in the garage. It thefore needs to be replaced by fresh electrolyte about once in eight months for a commercial-vehicle battery or once a year for a pleasure vehicle battery. Scientific American 1911
- Marketing cut-away of an Edison battery
- Edison's Patent for Reversible Galvanic Battery - 1901 (678722)
- Edison's Patent for Alkaline Battery - 1906 (827297)
- Edison's Patent for Storage-Battery Electrode-Plate - 1906 (831269)
- Edison's Patent for Insulated Battery Box - 1918 (1266780)
- The Edison Alkaline Storage Battery (1916)
- The Storage Battery: A practical treatise on the construction, theory, and use of secondary batteries (Treadwell, 1898)
- Comprehensive listing of Edison's more than 140 battery-related patents