Opel 1900 1973, Service Manual, Page: 28 / 625

BATTERY AND CABLES ALL MODELS 7
421 Test
1. Visual Inspection The step in testing the
Energizer Battery should be a visual in-
spection very often will save time, labor and
expense in determining the condition.
(a) Check broken or cracked case or cover.
Check loose terminal posts.
defective or mutilated sealing
(d) Check for other visible signs of physical damage.
Obvious as a result of conditions described
above the need for Energizer or battery
2. The “421” Test is a programmed test procedure
consisting bf a series of timed discharge and charge
events,
approximately 2 to 3 minutes, that
will determine the condition of the Energizer or bat-
tery with a high degree of accuracy when used in
with this entire test procedure. “421”
Testers produced by a number of different manu-
facturers their directions for tester operation
should be carefully followed. General comments on
overall “42 1” Tester operation follow:
(a) or batteries
should be charged
prior
to this test.
Defects within the unit can
be hidden by the charging and erroneous test results
will be
(b) Erratic, or extremely low, initial meter readings
may indicate poor connections at the tester termi-
nals.
and tight connections
forming the Test.
(c) All meter readings should be made
immediately
after the meter indicator light comes on even if the
meter needle is still moving.
(d) If additional discharges are required after the
initial
set meter indicator following the
discharge cycle.
Batteries designated as “bad” by the tester should
be replaced.
Batteries designated as “good” with no owner’s
complaint or indication of poor performance, should
be left in
Posts, cable clamps, and top should
be cleaned, water should be added and recharging
should be if required. For dependable
and reliable battery service, the battery should be in
at least a
per cent state-of-charge.
Batteries designated as “good” that are suspected
of being questionable because of owner complaint, or
age of the battery, should be further tested by the
Hydrometer Test.
HYDROMETER TEST OF BATTERY
The 421 Battery Test as described in the previous
paragraph is the fastest and most accurate means of
determining the serviceability of a one-piece cover
battery. However,
421 Battery Tester is not avail-
able, a hydrometer test may be used on a battery that
has failed to give proper service.
Hydrometer Test
1. Fully charge battery.
2. Measure specific gravity of each cell as described
in sub-paragraph below.
Decide battery serviceability as follows:
(a) If all cells read between 1.230 and 1.310, the
battery
is okay. All it needed was a full charge.
(b) After fully charging battery, if any cell reads less
than 1.230, the battery is defective and should be
replaced.
Use of Hydrometer
The Hydrometer measures the percentage of
ric acid in the battery electrolyte in terms of specific
gravity. As a battery drops from a charged to a dis-
charged
condition, the acid leaves the solution and
enters the plates, causing a decrease in specific
gravity of electrolyte. With a hydrometer, an indica-
tion of the concentration of the electrolyte is ob-
tained.
The specific gravity of the electrolyte varies not only
with the percentage of acid in the liquid, it also varies
with temperature. As temperature increases, the
electrolyte expands so that the specific gravity is re-
duced. As temperature drops, the electrolyte con-
tracts so that the
specific gravity
increases.
Unless
these variations in specific gravity are taken into
account, the specific gravity obtained by the hy-
drometer may not give a true indication of the con-
centration of acid in the electrolyte.
Correction can be made for temperature
by adding
usually referred to as 4 “points of gravity”, to
the hydrometer reading for every 10 degrees F. that
the electrolyte is above 80 degrees F. or subtracting
for every 10 degrees F. that electrolyte is below
80 degrees F. Figure IA-4 shows the exact correction
to use for any temperature above or below 80
degrees F., the three steps used in obtaining the cor-
rected or true specific gravity, and two examples
showing how it is figured.