comes in
covered with dirt, set it on the wash rack or in the sink and clean it
thoroughly before putting it on charge. In setting the batteries on
the charging bench, place all of them so that the positive terminal is
toward the right as you face the bench. The positive terminal may be
found to be painted red, or may be stamped "+", "P", or "POS". If the
markings on one of the terminals has been scratched or worn off,
examine the other terminal. The negative terminal may be found to be
painted black, or be stamped "-", "N" or "NEG".

If neither terminal is marked, the polarity may be determined with a
voltmeter, or by a cadmium test. To make the voltmeter test, hold the
meter wires on the battery terminals, or the terminals of either end
cell. When the voltmeter pointer moves to the right of the "0" line on
the scale, the wire attached to the "+" terminal of the meter is
touching the positive battery terminal, and the wire attached to the
"-" terminal of the meter is touching the negative battery terminal.
If this test is made with a meter having the "0" line at the center of
the scale, be sure that you know whether the pointer should move to
the left or right of the "0" line when the wire attached to the "+"
meter terminal is touching the positive battery terminal.

Another method of determining which is the positive terminal of the
battery is to use the cadmium test. When a reading of about two volts
is obtained, the prod held on one of the cell terminals is touching
the positive terminal. When a reading of almost zero is obtained, that
is, when the needle of the meter just barely moves from the "0" line,
or when it does not move at all, the prod held on one of the cell
terminals is touching the negative terminal. This test, made while the
battery is on open-circuit, is not a regular cadmium test, but is made
merely to determine the polarity of the battery.

The polarity of the charging line will always be known if the bench is
wired permanently. The positive charging wire should always be to the
right. If a separate switch is used for each battery (Figures 43 and
65), the wire attached to the right side of the switch is positive. If
the batteries are connected together by means of jumpers (Figures 44
and 47), the positive charging wire should be at the right hand end of
the bench as seen when facing the bench. If a constant-potential
charging circuit is used as shown in Figure 48, the positive bus-bar
should be