Dry, 4.5 Volt, Eveready No.703, 3 cells,
BA–9.—This battery is made up of three small cells in series, arranged side by side, and contained in a flat waterproof cardboard box sealed on top with a sealing compound. The terminals are two strips of brass, one soldered to the zinc can of one end cell, and the other to the brass cap of the carbon of the other end cell. The polarity is not marked but the shorter strip is positive, and the longer one is negative. This can be checked by noting that the shorter strip comes out of the sealing compound at a considerable distance from the edge of the battery, thus suggesting a connection to the inner or carbon (positive) terminal; whereas the longer strip comes out at the very edge of the compound, thus suggesting a connection to the outer or zinc can (negative) terminal. Each cell is about 2-1/4 inches long and three-fourths inch in diameter. The over-all dimensions of the battery are 2-7/16 inches by 2-11/16 inches by 7/8 inch thick. The weight is about one-half ounce or 0.03 pound. The battery has an open-circuit voltage of 4.3 volts, an internal resistance of 4 ohms, a shelf life of 3 to 6 months, and a service life of between 8 and 30 hours. A single cell has therefore an open circuit voltage of 1.43 volts, an internal resistance of 1.3 ohms, and a short-circuit current of 1.1 amperes. This same type of battery is in use in commercial flashlights, from which it was adopted by the Signal Corps for intermittent work in a commercial telephone set. The short life is due to the small size of the cells. In handling the battery care must be taken not to allow the terminal strips to be short-circuited by pieces of metal, etc. As ordinarily supplied, these strips are not long enough to touch each other when they are bent over on top of the cells, but if they should be long enough, the longer one must be cut off, to avoid the danger of a short circuit. The strips should not be bent back and forth, as they may be broken off so close to the sealing compound that it will be impossible to get a contact. At the present time BA–9 is used only in the portable telephone Type EE–5.
- Training Pamphlet no.7 Primary Batteries Jun., 1922 W.D.D. NO. 1112