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| Inspection |

| Periodic inspection should be made of storage batteries, including visual checks for cracked or broken covers, jars, or plates; for loose or corroded connectors; and for sediment in touch with plates. |

| A check of overall battery voltages should be made and recorded. Voltages on each cell should be read. Voltages should also be checked from both the positive terminal to ground and the negative terminal to ground. Grounds found in the batteries should be traced and removed. |

| If water is needed in any cell, only distilled water should be used. The electrolyte level should never fall below the low-water mark, and the water added should never raise the electrolyte level above the high-water mark. Care must be taken not to allow impurities to enter the batteries; any equipment that has come into contact with the electrolyte of one type of battery must never be used with the electrolyte of another type. |

| To determine the liquid level in alkaline batteries making use of metallic containers, a glass tube is required. The tube is inserted in the cell until it touches the plates. By placing a finger over the end of the tube and then withdrawing the tube, the electrolyte level above the plates becomes apparent. |

| Specific Gravity |

| The specific gravity of each cell of a lead battery should be read by a hydrometer and these readings corrected for temperature as needed. It is not necessary to read specific gravity on alkaline batteries unless there is some indication of a low electrolyte level or other abnormal condition. Hydrometer readings should always be taken before adding water to batteries. A hydrometer used in lead cells should never be used in alkaline cells. |

| As a guide to acceptable values for battery characteristics, the following table may be used: |

Lead Types

Alkaline Types

Specific gravity | 1.2101.224 | 1.1901.230
Water level above plates | 0.50.75 inch | 0.751.5 inch
Cell voltage | 2.152.20 | 1.431.47

| For overall acceptable battery voltage limits, multiply the cell voltage listed above by the number of cells in the battery. |

| Battery Charging |

| Charger. The output current charging rate should not exceed the maximum dc rating specified on the nameplate. From time to time, the charging rate may decrease as the rectifier stack ages. It can be maintained by advancing the switch shown in Fig. 15-12 by one position. |

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