Part 66 (1/2)

(a) Measure specific gravity of each cell. If any cell is badly discharged it is probably short-circuited, or contains impurities and had better be opened for inspection.

(b) Turn on all the lamps and measure the voltage of each cell. If any cell shows a voltage much less than 1.8 it is short-circuited or contains impurities, and should be opened for inspection.

(c) Examine the connections between cells for looseness or corrosion; and examine the connections between the battery and the generator, going over cables, switches, rheostats, etc. Make sure that you have a complete and closed charging circuit between the generator and the battery.

(d) If cutout is used on the switchboard, see that its contact points are smooth and clean, and that they work freely.

(e) Run the generator to see if it builds up a voltage which is sufficient to charge the battery, about 42 volts for a 16 cell battery.

If the generator is not working properly, examine it according to directions on page 451. Check up the field circuit of the generator to be sure that it is closed. A circuit-tester made of a buzzer and several dry cells, or a low voltage lamp and dry cells, or a hand magneto is convenient for use in testing circuits. Test armature windings and field coils for grounds.

By the foregoing methods you should be able to determine what is to be done. The following rules should also help:

Cleaning and renewal of electrolyte is necessary when:

(a) Sediment has risen to within one-half inch of the bottom of the plates.

(b) Much foreign material is floating in the electrolyte, or electrolyte is of a deep brown color.

Replacement of parts is necessary when

(a) Separators are cracked or warped. See page 346 for Separator troubles.

(b) Plates are defective. See rules on pages 339 to 346.

PREST-O-LITE FARM LIGHTING BATTERIES

[Fig. 300 Element from Prest-O-Light farm light cell]

The Prest-O-Lite battery which is designed for use in connection with farm lighting plants is known as the FPL type. Cells of 7, 9, 11, 13 and 15 plates are made, the number of plates being indicated by putting the figure in front of the type letters. A seven plate cell is thus designated as a 7 FPL cell, which has an 80 ampere hour capacity at the 8 hour continuous discharge rate.

The FPL cell, the construction of which is shown in Figs. 295, 300, 301, 302 and 303, has a sealed gla.s.s jar with a lead antimony cover.

The cover construction is shown in detail in Figs. 301 and 302.

Insulation between the posts and cover is provided by a hard rubber bus.h.i.+ng, a hard rubber washer, and a soft rubber washer. The bus.h.i.+ng is shaped like a ”T” with a hole drilled in the stem. The stem of the bus.h.i.+ng fits down into the post hole in the cover, the f.l.a.n.g.e at the top testing on the raised portion of the cover around the post hole.

The post has a shoulder a little less than halfway up from its lower end. Upon this shoulder is placed the hard rubber washer, and upon the hard rubber washer is placed the soft rubber washer. This a.s.sembly is fastened to the cover by the ”peening” process used in Prest-O-Lite automobile batteries as described on page 386. This forces the soft rubber washer tightly against the cover so as to make a leak proof joint-between the bus.h.i.+ng and cover. The ring of lead formed around the posts by the peening process supports the posts, plates, and separators, which therefore are suspended from the cell cover. The plate straps extend horizontally across the tops of the plates, and thus also act as ”hold-downs” for the separators. The separators are held up by two rectangular rubber bridges which fit Mito slotted extension lugs cast into the lower corners of the outside negative plates. An outside negative having these extension lugs is shown in Figure 303.

[Fig. 301 Cover of Prest-O-Light farm lighting cell]

[Fig. 302 Parts of Prest-O-Light farm lighting cell: nut, stud, terminal, hard rubber bus.h.i.+ng]

[Fig. 303a Parts of Prest-O-Light farming light cell: gla.s.s jar, rubber jar, rubber cell connector, gla.s.s cell connector]

[Fig. 303b Parts of Prest-O-Light farm lighting cell: positive plate and outside negative plate]

[Fig. 303c Parts of Prest-O-Light farm lighting cell: long lead jumper, jumper, separator, short lead jumper]

Specific Gravity of Electrolyte. The values of the specific gravity of Prest-O-Lite farm lighting batteries are as follows:

Battery fully charged reads 1.250 Battery three-fourths charged reads 1.230 Battery one-half charged reads 1.215 Battery one-fourth charged reads 1.200 Battery discharged completely reads 1.180