e 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 glass 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
bushing, a hard rubber washer, and