Part 66 (2/2)

These readings are to be taken with the electrolyte at a temperature of 80 Fahrenheit. Readings taken at other temperatures should be converted to 80. To convert readings at a lower temperature to the values they would have at 80, subtract one point for every two and one-half degrees temperature difference. For example, suppose a cell reads 1.225 gravity at 60. To find what the gravity would be if the temperature of the electrolyte were 80 divide the difference between 80 and 60 by 2-1/2, or 80 minus 60 divided by 21/2 equals 8. The gravity at 80 would therefore be 1.225 minus .008, or 1.217, which is the value of specific gravity to use. If the specific gravity is read at a higher temperature than 80, divide the difference between 80 and the temperature at which the gravity reading was taken by 21/2, and add the result to the actual gravity reading obtained. If, for example, the gravity were 1.225 at 100, the gravity at 80 would be 1.225 plus .008, or 1.233.

Charging Rates. The normal charging rate to be used in giving Prest-O-Lite batteries a regular charge or overcharge are as follows:

Battery Charging Rate ------- ---- 5 F.P.L. 5.0 amps.

7 F.P.L. 7.5 amps.

9 F.P.L. 10.0 amps.

11 F.P.L. 12.5 amps.

13 F.P.L. 15.0 amps.

15 F.P.L. 17.5 amps.

Rebuilding Prest-O-Lite Farm Lighting Batteries

Opening the Cell.

1. Make sure that the cell is as fully charged as possible. Since it is not very convenient to charge a single cell, a good time to open a cell for cleaning and repairing is immediately after the battery has been given an overcharge. See page 455.

2. Disconnect the cell from the adjoining ones.

3. Heat a thin bladed putty knife and insert it under the edge of the lead-antimony cover to melt the sealing compound. Run the knife all round the cover, heating it again if it should become too cool to cut the compound readily.

4. Grasp the lead posts above the cover and lift up gradually. This will bring up the cover, plates, and separators.

5. Place the plates on a clean board for examination. Use the instructions given on pages 339 to 346. Do not keep the plates out of the electrolyte long enough to let them dry, and the negatives heat up. If you cannot examine the plates as soon as you have removed them immerse them in 1.250 acid contained in a lead or non-metallic vessel until you can examine them.

6. In renewing the electrolyte, pour in as much new 1.250 acid as there was old electrolyte in the jar. (It is a.s.sumed that the electrolyte was up to the lower ridge of the gla.s.s jar before the cell was opened.) The new electrolyte must not have a temperature above 100 degrees when it is poured into the jar.

7. The separators can be pulled out easily when the plates are laid on their sides. All that is necessary is to remove the small rubber bridge at the bottom corners of the plates. The separators can then be pulled out. If the old separators are to be used again brush off any material that may be adhering to them, and keep them wet with 1.250 acid until they are replaced between the plates. Any separators that show cracks or holes, or that split while being replaced between the plates should be thrown away and new ones used.

8. It is not necessary to remove the sediment from the bottom of the jar unless it is within one half inch of the bottom of the plates. If the sediment is to be removed, carefully pour off the clear electrolyte into a lead, hard rubber, or earthenware jar, if the electrolyte is to be used again.

9. If one or two of the plates in either positive or negative groups need to be replaced it is best to burn a new plate to the strap without removing the peened cover. This is done by blocking under the row of plate lugs with metal blocks after cutting off old plate and cleaning the surface of strap. Insert new plate, the lug of which has been cut about 1/4 inch short, to allow for new metal. Choosing small oblong iron blocks of suitable size, build a form about the plate lug which fits same well. Now with a torch and burning lead fuse the new plate onto the old strap. When cool remove and test joint by pulling and slightly twisting the plate at the same time.

Sometimes one group of a starting and lighting battery may be in sufficiently good condition to pay to combine it with a new group, but this condition will very rarely, if ever, be met in farm lighting cell service. We advise the replacement of the complete cell element if either group is worn out, for the cost of repairs and of new group will probably not be warranted by the short additional life which the remaining old group will give.

10. Putting Repaired Cell Back into Service. After having finished all necessary cleaning, replacement, or repairs, remove all old sealing material, return the element with attached lead cover to the cell jar.

It is not necessary to reseal the cover to the jars this sealing is essential only for insurance against breakage or leakage in s.h.i.+pment.

Add through the vent plug opening sufficient cool acid of 1.250 Sp.

Gr. to reestablish the proper electrolyte level, which means that the electrolyte is brought up to the lower moulded gla.s.s ridge near the top of jar.

Connect the cell with any other repaired cells and charge at normal rate already indicated under ”charging rates” until dell voltage reads 2.5 or above, at 80. The positive to cadmium voltage should be at least 0.10 volts less than cell voltage itself. When this condition is obtained cell may be replaced in operating circuit with others and should give satisfactory service.

EXIDE FARM LIGHTING BATTERIES.

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