Disconnecting Cells.—The best method of disconnecting cells assembled with pillar straps, for the purpose of replacing broken jars, cleaning or taking out of commission, is to use a five-eighth inch twist drill, in a carpenter's brace, boring down into the top of the pillar about one-quarter inch; then pull off the connector sleeve from the pillar. By following this method, all parts may be used again.
When cells are equipped with top straps, the straps should be cut with a sharp knife or chisel midway between the cells.
Taking Batteries out of Commission.—Where a battery is to be out of service for several months, and it is not convenient to give it the freshening charge every two weeks, it should be taken out of commission.
| Degrees Baume | Specific Gravity | Degrees Baume | Specific Gravity | Degrees Baume | Specific Gravity | Degrees Baume | Specific Gravity |
|---|---|---|---|---|---|---|---|
| 0 | 1.000 | 17 | 1.133 | 34 | 1.306 | 51 | 1.542 |
| 1 | 1.007 | 18 | 1.142 | 35 | 1.318 | 52 | 1.559 |
| 2 | 1.014 | 19 | 1.151 | 36 | 1.330 | 53 | 1.576 |
| 3 | 1.021 | 20 | 1.160 | 37 | 1.342 | 54 | 1.593 |
| 4 | 1.028 | 21 | 1.169 | 38 | 1.355 | 55 | 1.611 |
| 5 | 1.036 | 22 | 1.179 | 39 | 1.368 | 56 | 1.629 |
| 6 | 1.043 | 23 | 1.188 | 40 | 1.381 | 57 | 1.648 |
| 7 | 1.051 | 24 | 1.198 | 41 | 1.394 | 58 | 1.666 |
| 8 | 1.058 | 25 | 1.208 | 42 | 1.408 | 59 | 1.686 |
| 9 | 1.066 | 26 | 1.218 | 43 | 1.421 | 60 | 1.707 |
| 10 | 1.074 | 27 | 1.229 | 44 | 1.436 | 61 | 1.726 |
| 11 | 1.082 | 28 | 1.239 | 45 | 1.450 | 62 | 1.747 |
| 12 | 1.090 | 29 | 1.250 | 46 | 1.465 | 63 | 1.768 |
| 13 | 1.098 | 30 | 1.261 | 47 | 1.479 | 64 | 1.790 |
| 14 | 1.107 | 31 | 1.272 | 48 | 1.495 | 65 | 1.812 |
| 15 | 1.115 | 32 | 1.283 | 49 | 1.510 | 66 | 1.835 |
| 16 | 1.124 | 33 | 1.295 | 50 | 1.526 |
NOTE.—The characteristic properties of concentrated sulphuric acid are very marked. Its freedom from odor, oily appearance, and its great weight, distinguish it from other liquids. The pure concentrated commercial acid has a density which usually reaches 1.842, and its boiling point is about 640° F. The absolutely pure acid is perfectly colorless, but usually even that used in laboratories has a peculiar grayish color, due to slight traces of organic matter. Sulphuric acid is exceedingly hydroscopic, and when exposed to the air it rapidly increases in bulk, owing to absorption of atmospheric moisture.
NOTE.—Clamps not made of metal similar to that of the connecting strips, frequently give trouble from the galvanic action due to the contact of dissimilar metals in the presence of moisture which causes the destruction of either the connecting strip or the clamp. Such troubles can be avoided by placing a thin strip of sheet zinc between the lead strip and the clamp. Under these circumstances the zinc will crumble away, and can be replaced without much inconvenience and very little expense, while the clamps and connecting strips will remain uninjured.
| Per cent. of Sulphuric Acid | Specific Gravity | Per cent. of Sulphuric Acid | Specific Gravity |
|---|---|---|---|
| 100 | 1.842 | 23 | 1.167 |
| 40 | 1.306 | 22 | 1.159 |
| 31 | 1.231 | 21 | 1.151 |
| 30 | 1.223 | 20 | 1.144 |
| 29 | 1.215 | 19 | 1.136 |
| 28 | 1.206 | 18 | 1.129 |
| 27 | 1.198 | 17 | 1.121 |
| 26 | 1.190 | 16 | 1.116 |
| 25 | 1.172 | 15 | 1.106 |
| 24 | 1.174 | 14 | 1.098 |
Ques. Describe the method of taking a battery out of commission.
Ans. The battery is charged in the usual manner, until the specific gravity of the electrolyte of every cell has stopped rising over a period of one hour (if there be any low cells, due to short circuits or other cause, they should be put in condition before the charge is started, so that they will receive the full benefit of it). The cells may now be disconnected and covers and elements removed from the jars, (if sealed, the compound is loosened with a hot putty knife). The elements are placed on their sides with the plates slightly spread apart at the bottom, the separators withdrawn, and the positive and negative groups pulled apart. The electrolyte is washed off with a gentle stream of water and the plates allowed to drain and dry.[7] The positive plates are ready to be put away. When dry, the negatives are completely immersed in electrolyte (of about 1.275 specific gravity), and allowed to soak for three or four hours. The jars may be used for this purpose. After rinsing and drying, they are ready to be put away; wash also the rubber separators.
Wood separators, after having been in service, will not stand much handling and had better be thrown away. If it be thought worth while to keep them, they must be immersed in water or weak electrolyte, and in re-assembling, the electrolyte must be put into the cells immediately, as wet wood separators must not stand exposed to the air.