(c) If only one cell requires a considerable amount of water to bring up the level of its electrolyte, and the bottom of the wooden battery ease shows no sign of being rotted, that cell is probably "dead," due to in internal short-circuit. To test for "dead" cells, turn on the lamps and measure the voltage of each cell. A dead cell will not give any voltage on test, may give a reversed voltage reading, or at the most will give a very low voltage. A battery with a dead cell should be opened for inspection.
(d) If the bottom part of the wooden battery case is rotted, and a considerable amount of water had to be added to any or all cells to bring up the level of the electrolyte, the battery has leaky jars and must be opened to have the leaky jars replaced by good ones.
If there is any doubt in your mind as to whether any or all jars are leaking, fill the cells with distilled water and let the battery stand for twelve to twenty-four hours. If at or before the end of that time the electrolyte has, fallen below the tops of the plates in any or all cells, these cells have leaky Jars and the battery must be opened and the leaky jars replaced with good ones. The electrolyte which leaks out will wet the bench or on which the battery is placed and this is another indication of a leaky jar.
General Inspection
In addition to the tests which have been described, a general inspection as outlined below will often be a great help in deciding what must be done.
1. Is battery loose? A battery which is not held down firmly may have broken jars, cracked sealing compound around posts or between posts and separators, and active material shaken out of the grids. There may also be corrosion at the terminals.
2. Are cables loose? This will cause battery to be in a run down condition and cause failure to crank engine.
3. Is there corrosion at the terminals? This will cause battery to be in a run-down condition and cause failure to start engine. Corrosion is caused by electrolyte attacking terminals. A coating of vaseline on the terminals prevents corrosion.
4. Is top of battery wet? This may be due to addition of too much water, overheating of battery, cracks around posts and between posts and cover, electrolyte thrown out of vents because of battery being loose, or electrolyte or water spilled on battery. Such a condition causes battery to run down.
5. Is top of case acid soaked? This is caused by leaks around posts or between covers and jars, flooding of electrolyte due to overheating or due to addition of too much water, or by electrolyte spilled on covers.