admium
readings to be obtained. The charging rate should be high enough to
give cell voltages of 2.5-2.7 when testing negatives. Otherwise it may
not be possible to get satisfactory negative-Cadmium reading.
Separators which have been allowed to become partly dry at any time
will also make it difficult to obtain satisfactory negative-Cadmium
readings.

HIGH RATE DISCHARGE TESTERS

(See page 265 for directions for making tests.)

Figure 128 shows a high rate discharge cell tester. It consists of a
handle carrying two heavy prongs which are bridged by a length of
heavy nichrome wire. When the ends of the prongs are pressed down on
the terminals of a cell, a current of 150 to 200 amperes is drawn from
the cell. A voltage reading of the cell, taken while this discharge
current is flowing is a means of determining the condition of the
cell, since the heavy discharge current duplicates the heavy current
drawn by the starting motor. Each prong carries a binding post, a low
reading voltmeter being connected to these posts while the test is
made. This form of discharge tester is riot suitable for making
starting ability discharge tests, which are described on page 267.

Other forms of high rate discharge testers are made, but for the shop
the type shown in Figure 128 is most convenient, since it is light and
portable and has no moving parts, and because the test is made very
quickly without making any connections to the battery. Furthermore,
each cell is tested separately and thus six or twelve volt batteries
may be tested without making any change in the tester.

For making starting ability discharge tests at high rates, a carbon
plate or similar rheostat is most suitable, and such rheostats are on
the market.

[Fig. 128 High rate discharge tester]

[Fig. 129 Paraffine dip pot]

PARAFFINE DIP POT

Paper tags are not acid proof, and if acid is spilled on tags tied to
batteries which are being repaired, the writing on the tags is often
obliterated so that it is practically impossible to identify the
batteries. An excellent plan to overcome this trouble is to dip the
tags in hot paraffine after they have been properly filled out. The
writing on the tags can be read easily and since paraffine is acid
proof, any acid which may be spilled on the paraffine coated tags will
not damage the tags in any way.

Figure 129 shows a paraffine dip pot. A small earthenware jar is best
for this purpose. Melt the paraffine