TM 10-6140-200-14
CHAPTER 3
FIELD SERVICING AND REPAIR
Section I. TROUBLESHOOTING
specific gravity shows no change during a 3 hour period
3-1. General
while taking hourly readings. With automatic charging
a. In addition to the required routine maintenance de-
equipment, the battery may have to be placed on
equalizing charge two or three times. If a battery is badly
scribed in Chapter 2, Section III, storage batteries may, at
some time during their service life, require more extensive
sulfated, the specific gravity may rise only 30 to 40
or unusual care. Such care should be given as soon as it
points (.030 to .040) during the first charge.
has been determined that a problem exists or that trouble
may be developing. As a result, this section deals with the
(4) Place the battery into service and discharge it to a
means of identifying existing or impending problems and
fully discharged condition.
offers possible solutions.
(5) Charge the battery again until the specific gravity
shows no change during a 3 hour period.
most common problems which could occur during a
(6) Repeat the cycling process until the specific gravity
battery's lifetime. If the suggested operational remedies
are ineffective, it may be assumed that there is an internal
rises to within 30 points of a normal fully charged
battery, then place the battery back in routine service.
problem and it will be necessary to disassemble the cell or
Even though specific gravities may be lower than normal
cells to inspect the elements and sediment well. If the
they should not vary much from cell to cell. If they do,
cause of the problem can only be corrected by com-
problems other than sulfation may be present. If the
pletely rebuilding cells or the battery, this should be
spread between the highest and the lowest gravity reading
reported to the designated person in authority.
is 50 points or more, refer to the Troubleshooting Chart,
3-2. Restoring a Sulfated Battery
battery still has not responded to treatment, it should be
replaced.
a. Undercharging a battery, even to a small degree, if
continued, leads to excessive "sulfation." The same is true
3-3. Correcting Excessive Self-Discharge
of batteries which have been left standing in an uncharged
state for an extended period. High temperatures rapidly
a. While a storage battery is in a charged state, a local
accelerate sulfation when batteries are left standing in a
electrochemical reaction takes place within the cells which
partially charged condition. The cells of a sulfated battery
causes very gradual discharging. This is known as self-
will give low specific gravity and voltage readings. The
discharge. A small amount is quite normal in motive
battery will not become fully charged after a single
power batteries where grids are made from antimonial
normal charging when sulfation has taken place over a
prolonged period.
lead. The rate of self-discharge is temperature related,
however, and increases significantly as temperatures rise.
b. If the sulfation has not progressed too far, it may be
possible to restore the battery to a serviceable condition
loss of specific gravity. The normal rate at 77 degrees F.
by using the following special procedures:
to 80 degrees F. causes a loss in specific gravity of about
one point (.001) per day. This becomes of concern only
(1) Thoroughly clean the battery (See Paragraph 2-14).
when a wet battery is to be stored for weeks at a time. It
can be ignored as a factor in normal battery operation.
(2) Bring the electrolyte level up to a point which is
just visible over the separator protector by adding
b. It is possible, however, particularly during the latter
approved water.
stages of a battery's life, for the rate of discharge to
become much greater and even limit the battery's duty
(3) Put the battery on charge at the prescribed finishing
cycle. Excessive selfdischarge may be caused by defective
rate until the rated ampere-hour capacity has been
separators or plates which have become shorted at the
returned to the battery. Record the voltage and specific
edges. Edge shorting is usually caused by loss of positive
gravity readings. Correct the specific gravity readings for
active material which can fill the sediment well or build
temperature by using Table 2-1. If the temperature at any
up on the top or sides of the plates and eventually bridge
time during these procedures exceeds 110 degrees F., stop
the space between the positives and negatives. If a shorted
the charge and allow the battery to cool to 90 degrees F.
condition seems likely, the element should be pulled for
or below before continuing. Charge the battery until the
examination and the defective separator replaced, shorts
3-1
