READINGS WHEN CHARGED
A small amount of water might do more harm
AND DISCHARGED
than good in spreading the acid burn. Afterwards,
apply a salve such as petrolatum, boric acid, or
At the conclusion of a 10-hour discharge test
zinc ointment. If none of these salves are
on a battery, the closed-circuit voltmeter reading
available, clean lubricating oil will suffice. You
will be about 1.75 volts per cell. The specific
can neutralize acid spilled on clothing with diluted
gravity of the electrolyte will be about 1.060. At
ammonia or a solution of baking soda and water.
the completion of a charge, the closed-circuit
voltmeter reading at the finishing rate will be
about 2.4 to 2.6 volts per cell. The specific gravity
CAPACITY
of the electrolyte corrected to 80F will then be
between 1.210 and 1.220.
The capacity of a battery is measured in
ampere-hours (amp-hr). The amp-hr capacity is
TYPES OF CHARGES
equal to the product of the current in amperes and
the time in hours during which the battery is
The following types of charges may be given
supplying this current. The amp-hr capacity varies
to a storage battery, depending on the condition
inversely with the discharge current. The size of
of the battery:
a cell is determined generally by its amp-hr
capacity. The capacity of a cell depends on many
Initial charge
factors. The most important of these are as
follows:
Normal charge
1. The area of the plates in contact with the
Equalizing charge
electrolyte
2. The quantity and specific gravity of the
Floating charge
electrolyte
3. The type of separators
Emergency charge
4. The general condition of the battery (degree
of sulfating, plates buckled, separators
Initial Charge
warped, sediment in bottom of cells, and
so forth)
Initial charge is a long, low-rate, forming
charge that is given to place a new battery in
5. The final limiting voltage
service. When a battery is shipped dry, the battery
may be in the uncharged or dry-charged condi-
tion. After the electrolyte has been added, the un-
RATING
charged battery must be given an initial charge.
The addition of electrolyte to the dry-charged
Storage batteries are rated according to their
battery is sufficient for an initial charge. To
rate of discharge and amp-hr capacity. Most
charge the battery, follow the manufacturer's
batteries are rated according to a 10-hour rate of
instructions. These are shipped with each battery.
discharge. That is, if a fully charged battery is
If the manufacturer's instructions are not
completely discharged during a 10-hour period,
available, refer to the instructions in current
it is discharged at the 10-hour rate. Thus, if a
directives.
battery can deliver 20 amperes for 10 hours, the
battery has a rating of 20 10, or 200 amp-hr.
Normal Charge
The 10-hour rating is equal to the average
current that a battery can supply without
A normal charge is a routine charge. You
interruption for 10 hours.
should give it following the nameplate data during
the ordinary cycle of operation. It restores the
All standard batteries deliver 100 percent of
battery to its charged condition. Observe the
their available capacity if they are discharged in
following steps:
10 hours or more. But they will deliver less than
their available capacity if they are discharged at
1. Determine the starting and finishing rate
a faster rate. The faster they discharge, the less
from the nameplate data.
amp-hr capacity they have.
10-14
