Q. Describe the casemate battery. (See Fig. 103.)
A. This is a storage-battery of the standard chloride accumulator type. It is composed of 40 cells, type D-5 (D = size of plate 5, the number of plates). D-5 has two positive and three negative plates, each 6" × 6". Positive plates are of a brownish color, negative grayish. These plates are contained in a glass jar nearly filled with electrolyte (one part sulphuric acid to five parts distilled water by volume makes electrolyte of 1·210 specific gravity. The acid must be poured into the water.)
These glass jars are placed in trays of sand and the trays rest on glass insulators. The normal charge and discharge rate of this battery is 5 amperes, although in starting the motor generator a much higher current is drawn from the battery. The voltage is about 80.
Q. What precautions are necessary to keep it in order?
A.
1o Do not overcharge, overdischarge, or allow to stand completely discharged. (Battery should be charged when discharge is 1.8 volts per cell.)
2o Keep plates covered with electrolyte about ¾ inch above top of plates. If not at proper height add distilled water.
3o Keep cells free from sediment.
4o A record of each cell (voltage and specific gravity) should be kept each time the battery is charged, and this should be done about once a week.
5o The indications of a complete charge are: when positive plates have a deep chocolate color, negative light slate, cells gas freely, each cell reads about 2·5 volts, and 1.210 specific gravity, and when no perceptible rise in voltage occurs for a lapse of 10 to 15 minutes.
6o If any low cells develop, bring them back into condition immediately.
(a) If voltage is very low, look for sediment or foreign matter, then charge separately.
