("National" batteries). The batteries are made up of several cells,
usually two or three, each cell representing approximately 2 volts when
battery is on "open circuit" (neither charging nor discharging). It
is sometimes advisable to take individual readings of the cells, both
to determine on charge if all the cells be evenly charged, and also
on discharge to be sure that the cells are evenly discharged. To do
this, a low-reading voltmeter must be used with prods attached to the
voltmeter leads that can be forced into the terminals so as to insure
good contacts. To test the positive end cell, put the positive prod on
the positive terminal of the battery and the negative prod into small
hole back of positive terminal in hard rubber cover. Middle cell (in
6 volt, type "Y" batteries) is tested by inserting the positive prod
in the small hole back of the positive terminal, and the negative prod
in small hole back of negative terminal. In the 120 ampere hour, Auto
type of battery, the middle cell is tested by inserting the positive
prod in the small hole back of the positive terminal and the negative
prod on the middle terminal. The negative end cell is tested by putting
the negative prod on the negative terminal and the positive in the
small hole in rubber cover back of the negative terminal. A charging
cell at end of charge should read about 2.55 volts. A fully charged
cell on open circuit should read about 2.1 volts. Since open circuit
readings vary under different conditions, as to age, acid, etc., little
significance should be attached to them. A discharged cell voltage will
vary considerably with the many different coils, engines, etc., but in
the majority of cases should read between 1.8 to 1.9 volts, while motor
is in operation.]
For rapid charging, when a battery has to be charged in four hours, the
current should vary about as follows:
40 per cent. of total 1st hour
25 " " " " 2nd "
20 " " " " 3rd "
15 " " " " 4th "
For quick charging in three hours the rates should be: 50 per
cent. 1st hour; 33⅓ per cent. 2nd hour; 16⅔ per cent. 3rd
hour.
=Mercury Arc Rectifier.=—This is a device for obtaining direct current
from alternating current for use in charging storage batteries. The
transformation is obtained at a low cost, because the regulation is
obtained from the alternating side of the rectifier, while the current
comes from the direct current side.
[Illustration: FIGS. 1,132 to 1,134.—Mercury arc rectifier outfit,
or charging set. The cuts show front, rear, and side views of the
rectifier, illustrating the arrangement on a panel, of the rectifier
tube with its connection and operating devices.]
The theory is as follows: In an exhaust tube having one or more mercury
electrodes, ionized vapor is supplied by the negative electrode or
cathode, when the latter is in a state of "excitation." This condition
of excitation can be kept up only as long as there is current flowing
toward the negative electrode.
If the direction of the voltage be reversed, so that the formerly
negative electrode is now positive, the current ceases to flow, since
in order to flow in the opposite direction it would require the
formation of a new negative electrode, which can be accomplished only
by special means. Therefore, the current is always flowing toward one
electrode—the cathode, which is kept excited by the current itself.
Such a tube would cease to operate on alternating current voltage
after half a cycle if some means were not provided to maintain a flow
of current continuously towards the negative electrode.
[Illustration: FIG. 1,135.—Elementary diagram of mercury arc rectifier
connections. A, A´, graphite anodes; B, mercury cathode; C, small
starting electrode; D, battery connection; E, and F reactance coils; G
and H, transformer terminals; J, battery.]
=Ques. Describe the construction and operation of a mercury arc
rectifier.=
Ans. Fig. 1,135 is an elementary diagram of connections. The rectifier
tube in an exhausted glass vessel in which are two graphite anodes
A, A´, and one mercury cathode B. The small starting electrode C is
connected to one side of the alternating circuit, through resistance;
and by rocking the tube a slight arc is formed, which starts the
operation of the rectifier tube. At the instant the terminal H of
the supply transformer is positive, the anode A is then positive, and
the arc is free to flow between A and B. Following the direction of
the arrow still further, the current passes through the battery J,
through one-half of the main reactance coil E, and back to the negative
terminal G of the transformer. When the impressed voltage falls below
a value sufficient to maintain the arc against the reverse voltage of
the arc and load, the reactance E, which heretofore has been charging,
now discharges, the discharge current being in the same direction as
formerly. This serves to maintain the arc in the rectifier tube until
the voltage of the supply has passed through zero, reversed, and
built up such a value as to cause the anode A to have a sufficiently
positive value to start the arc between it and the cathode B. The
discharge circuit of the reactance coil E is now through the arc A'B
instead of through its former circuit. Consequently the arc A'B is now
supplied with current, partly from the transformer, and partly from the
reactance coil E. The new circuit from the transformer is indicated by
the arrows enclosed in circles.
=Ques. How is a mercury arc rectifier started?=
Ans. A rectifier outfit with its starting devices, etc., is shown in
figs. 1,132 to 1,134. To start the rectifier, close in order named
line switch and circuit breaker; hold the starting switch in opposite
position from normal; rock the tube gently by rectifier shaker. When
the tube starts, as shown by greenish blue light, release starting
switch and see that it goes back to normal position. Adjust the
charging current by means of fine regulation switch on the left; or, if
not sufficient, by one button of coarse regulation switch on the right.
The regulating switch may have to be adjusted occasionally during
charge, if it be desired to maintain the charging current approximately
constant.
=Capacity.=—The unit of capacity of a storage cell is the _ampere
hour_, that is, the ability to discharge one ampere continuously
for one hour. For instance, a 100 ampere hour battery will give a
continuous discharge of 12½ amperes for eight hours. It should
theoretically give a discharge of 25 amperes continuously for four
hours, or 50 amperes for two hours, but in reality, the ampere hour
capacity decreases with an increase of discharge rate.
It requires, theoretically .135 ounces of metallic lead on either
element reduced to sponge lead or to lead peroxide to produce one
ampere hour; in practice, from four to six times this amount is
required.
The reason for this is because it is impossible to reduce all
the active material, to bring every particle in contact with
the electrolyte, or to cause every part to be penetrated by the
current.
Experiments show that from .5 to .8 ounces of sponge lead, and from .53
to .86 ounces of metallic lead converted into peroxide, are required on
their respective elements to produce a discharge of one ampere hour at
ordinary commercial rates.
The capacity increases with the temperature, being about one per cent.
for each degree Fahr. increase in temperature.
Battery capacity depends on the size and number of plates; the quantity
of active material present, and the quantity of electrolyte.
For an eight hour rate of discharge and 60 degrees temperature, the
capacity of American batteries varies from 40 to 60 ampere hours per
square foot of positive plate surface ( = 2 × number of positive plates
in parallel × length × breadth).
The following table gives the variation of capacity for different rates
of discharge:
Capacity Variation for Different Discharge Rates
+——————————-+——————————————————————+
| Discharge | Per cent of capacity |
| rate | at 8 hour rate |
+——————————-+——————————————————————+
| | =Plante= | =Faure= |
| 8 hour | 100% | 100% |
| 6 hour | 96% | 96% |
| 4 hour | 80% | 88% |
| 2 hour | 61% | 70% |
| 1 hour | 56% | 48% |
+——————————-+——————————+——————————-+
[Illustration: FIG. 1,136.—"Exide" connector puller for removing
connectors.]
=Ques. How may the capacity of a battery be increased?=
Ans. By mixing organic materials with the lead oxide, _but any such
mixture is always accompanied by a rapid deterioration of the plates_.
=Discharging.=—In discharging a battery its voltage should never be
allowed to fall below 1.8 volts, under load, thus leaving about 30 per
cent. of the total capacity unused. The normal discharging current
may be equal to the normal charging current, but a discharge equal to
3 or 4 times the normal may be given without injury to the plates.
Some types may be discharged at even six or seven times the normal
rate. In such cases, however, the capacity will be reduced in the same
proportion, as before explained in the paragraph dealing with battery
capacities.
[Illustration: FIGS. 1,137 to 1,151.—Parts of the Witherbee battery.
1, jar; 2, inside cover; 3, cover; 4, handle; 5, vent cap; 6, cover,
screws, nuts and washers; 7, handle eyes, nuts and washers; 8, rubber
covered nut; 9, spannernut; 10, plate strap for positive plates;
11, plate strap for negative plates; 12, rubber separator; 13, wood
separator; 14, positive group of plates; 15, negative group of plates;
16, positive plate; 17, negative plate; 18, cell connector. An element
consists of a complete set of plates bound together on strap, with wood
and rubber separators for a single cell. Positive plates are brown,
negative plates, gray.]
=Ques. What is the effect of discharging too rapidly?=
Ans. It tends to break the plates, and in the case of pasted plates, a
very sudden discharge will dislodge the paste.
=Ques. How is the discharge capacity of a storage battery stated?=
Ans. In ampere hours. This, unless otherwise specified, refers to
its output of current at the eight hour rate. Most manufacturers of
automobile batteries specify only the amperage of the discharge at
three and four hours. Thus, at the eight hour rate, a cell which will
discharge at ten amperes for eight hours is said to have a capacity
of eighty ampere hours. It does not follow that eighty amperes would
be secured if the cell were discharged in one hour. It is safe to say
that not more than forty amperes would be the result with this rapid
discharge.
As a general rule, the one hour discharge rate is four times
that of the normal, or eight hour discharge, and considerations
of economy and prudence suggest that it should never be
exceeded, if, indeed, it ever be employed. The three hour
discharge, which is normally twice that of the eight hour,
is usually the highest that is prudent, while the four hour
discharge is the one most often employed in vehicles for the
average high speed riding.
=Ques. What should be the maximum rate of discharge?=
Ans. The one-hour rate; this when used, should not extend over fifteen
or twenty minutes. In the case of regulating batteries a forty-five
minute rate of discharge may be allowed for one or two minutes during
great fluctuations of load.
=Ques. How does the capacity decrease?=
Ans. It decreases with the increase in current output.
An 80 ampere hour cell, capable of delivering 10 amperes for 8
hours, would, when discharged at 14 amperes, have a capacity of
70 ampere hours; when discharged at 20, its capacity would be
60; and when discharged at 40, its capacity will have decreased
from 80 to 40 ampere hours.
[Illustration: FIG. 1,152.—The Edison alternating current rectifier.
It consists of an electro-mechanically operated valve which allows
current waves of only one polarity to pass through it from the
alternating current circuit to the battery which is to be charged. An
indicating snap switch of the usual form controls the starting and
stopping of the charging current. The rectifier gives any desired
charging rate within its capacity. The illustration shows the rectifier
connected up and charging an ignition battery of five Edison cells.
The connections consist of the usual connecting cord and plug and a
charging lead running from the plus side of the charging terminals
on the rectifier to the plus pole of the battery, and another lead
connecting the negative terminals as shown. In turning the snap switch
to the "on" position, the proper charging current will flow into the
battery. When charging is completed, the switch is turned to the "off"
position and the battery leads disconnected.]
=Ques. What, in general, are the indications of the quantity of
electricity remaining within a cell?=
Ans. The voltage, and the density of the electrolyte.
=Ques. What should be done after discharging?=
Ans. Whenever possible the battery should be immediately charged.
=The Battery Room.=—Precautions should be taken to prevent any direct
sunlight falling on the battery cells in glass jars, as the breakage
of such jars due to unequal expansion of the different portions of the
glass, is a source of constant trouble and danger.
[Illustration: FIG. 1,153.—Permanent connections for Edison rectifier.
As shown, the rectifier is connected to a small switch and cutout.]
The exclusion of direct sunlight also tends to keep the evaporation of
the electrolyte at a minimum.
[Illustration: FIG. 1,154.—Edison Alternating Current rectifier; view
with cover open showing parts. B, primary circuit cord; C, condenser;
E, primary relay; F, secondary switch; S, alternating circuit switch;
T, transformer.]
[Illustration: FIG. 1,155.—Vibrating unit of Edison alternating
current rectifier. M, permanent magnet; N, carbon vibrating contact; O,
comb radiator; P, primary circuit coil; Q, vibrator adjustment screw.]
Operation of Edison Rectifier
The operation of the Edison rectifier may be explained as
follows with the aid of figs. 1,154 to 1,156 (the parts being
uniformly lettered in the figures): The primary circuit taken
from the alternating current mains by the cord B, embraces the
primary winding of the transformer T, a condenser C, and the
coils P, of the vibrating units, fig. 1,155.
The secondary circuit from the transformer embraces the
massive carbon and copper contacts (N and O, fig. 1,156) which
pass only the positive waves of the alternating current, for
charging batteries or other duty.
An ammeter and rheostat may be placed in this charging circuit
if the current is to be varied, or a fixed connection may be
substituted on the base of the rectifier if it is to be used
for the maximum duty of 8 or 16 amperes.
The vibrating unit (fig. 1,155), which operates in a manner
similar to the well known action of a polarized relay, includes
a permanent magnet M; the coil in the primary circuit P; the
vibrating armature of steel with removable carbon contact N;
the stationary copper contact with comb top for heat radiation
O, and the screw Q for adjusting the amplitude of the armature
vibration.
The vibrating armature of each unit is divided into two parts,
which gives flexibility, affords increased current capacity
and minimizes sparking, the two leads shown being connected
together in one circuit.
A primary relay and a secondary switch (E and F, figs. 1,154
and 1,156), close their contacts when current is flowing.
Upon failure of the main alternating current line they operate
to open the charging circuit. A storage battery is thus
prevented discharging through the rectifier.
Upon resumption of the main alternating current, the rectifier
starts automatically.
[Illustration: FIG. 1,156.—Elementary diagram of connections.]
Every battery room should be provided with a water tap and sink. The
floor should be paved with vitrified brick, preferably blue or yellow
in color, of diamond pattern and sloping in all directions toward
suitable drains. A floor of this type can be easily washed by flooding
with water, and its patterns tend to keep it dry under foot at all
times. Wooden floors are rotted very quickly by acid spillings and by
the spray.
The room should be kept absolutely clear of everything, which may be
injured, by the sulphuric acid fumes and it should be well ventilated
to insure the safety and good health of the attendants.
A battery, even at rest, gives off hydrogen which when diluted with air
forms a mixture which is very liable to explode if brought in contact
with any kind of flame. Unless proper ventilation be provided, the
breaking of the connection when a current is flowing, or the lighting
of a bare flame lamp in the battery room would be dangerous.
=Battery Attendants and Workmen.=—Those employed in setting up
batteries are liable to suffer from soreness of hands and the
destruction of clothing unless proper precautions be taken to prevent
the same. In order to avoid these troubles, the boots should be painted
with paraffine mixed with an equal quantity of beeswax.
The clothing should be of woolen material, which, unlike cotton, is
practically unaffected by the acid. If cotton shirts be worn, they
should be dipped in a strong solution of washing soda and then rough
dried.
An apron of sacking, backed with flannel should be worn over all the
other clothes. A bottle of strong ammonia should be kept in the
battery room at all times, and in case of an accidental splash of acid
on the clothes, the immediate application of a small quantity of the
ammonia, by means of the stopper, will at once neutralize the acid and
prevent it burning a hole in the material. A pail containing water made
strongly alkaline with washing soda should also be kept conveniently
at hand during all operations in the battery room. The hands should be
dipped occasionally in this water in order to prevent the skin smarting
and becoming sore under the action of the acid.
[Illustration: FIG. 1,157.—Interior of storage battery room showing
arrangement of cells. A, are the cell insulators; B, wooden stringers;
C, supporting pieces.]
If a splash of acid should happen to enter the eye, it should
be washed at once with clean water, warm water preferably, and
then put one or two drops of olive oil into the eye. If olive
oil be not immediately available, any kind of engine oil is
better than none at all.
=Points on Care and Management.=—In setting up storage cells, they
should be placed in as few tiers as possible, and in such a manner that
the direct rays of the sun are not allowed to fall upon the cells. The
rays of the sun are likely to crack the glass. This is probably due to
the unequal expansion of the glass, for it has been found that jars
which are carefully annealed never crack in this manner. Of course, the
latter precaution does not apply to large batteries, where lead lined
wooden tanks or solid lead boxes are used.
In installing plants where expert attendance is not to be had, it is
well to place in the circuit two magnetic cut outs, one set for maximum
current, and the other for minimum voltage, so that the battery cannot
be discharged too low.
=Ques. How should the cells be placed?=
Ans. They should be placed as shown in fig. 1,151, on insulators A,
resting on wooden stringers B, and supporting pieces C placed on the
floor. The insulators are usually of glass or porcelain, which in
certain patterns may be filled with oil, to insure better insulation as
shown in figs. 1,165 and 1,166.
In setting up a battery, it should be remembered that plates
deteriorate on standing exposed to the air. They should,
therefore, be unpacked and set up immediately on arrival. When
they are entirely connected up, they are ready for the addition
of the electrolyte, and for the forming charge, which they
should receive immediately.
=Ques. How should the wooden stringers, shelves, cell boards, and trays
be treated?=
Ans. They should be thoroughly varnished to insure cleanliness as well
as good insulation.
Outside of each cell and close to the mouth, melted paraffine
should be applied by means of a brush, so as to form a
band about an inch wide, for the purpose of preventing the
electrolyte creeping over the top of the jar, wetting the
outside, and thereby impairing the insulation.
=Ques. What should be done to avoid waste of current by leakage?=
Ans. Each cell of the battery must be thoroughly insulated.
=Ques. What is the effect of verdigris which forms on the terminals?=
Ans. It is a poor conductor and should therefore be removed and the
terminals kept bright and clean to insure the proper flow of the
current.
[Illustration: FIG. 1,158.—Charging "Champion" battery with charging
plug. Where direct lighting current is available, recharging may be
done by means of the charging plug. First insert the plug in a regular
socket. Then screw a 50 c.p. lamp into the plug and turn on. To tell
the positive from the negative, lay both wires on a small piece of red
litmus or test paper moistened. The negative wire makes a mark on the
paper. This wire must go to the negative post of battery. This will
fully charge the "6-25-G" battery in 15 to 20 hours.]
=Ques. What precautions should be taken in unpacking cells?=
Ans. The plates should be handled carefully. When they are sent out
from the factory already built into sections, they should be unpacked
without disturbing a single plate. In all cases, every particle of
packing, straw, hay and any chips and bits of parts should be carefully
removed, and all the dust should be blown out of the spaces between the
plates by means of a bellows or other similar device.
NOTE.—_Champion directions for repairs._ To replace broken
jars in a battery remove the lid and lift out elements bodily.
Empty the good jars with a syringe or by tilting the battery
over. Never put the acid in any vessel except glass, stone
or lead. Put new jars in place same as others and run melted
paraffine around the edges. The wax must be broken off the
elements that are to go into new jars and be poured on again.
Fill the jars with acid to ¾" from tops. Melt the broken wax
in a tin ladle and pour over the acid about ½" thick. Do not
fill with wax to tops of jars. When the wax gets cold it will
be found to have shrunk away from the edges of the jars. Fill
up the opening with a little melted paraffine wax by means of a
squirt can. Cut a small hole in the middle of the wax seal for
a vent. Smear the brass posts and terminals and inside of case
with vaseline to prevent creeping of the acid. The "6-25-G"
requires one-half gallon of acid and the "6-50-G" one gallon.
Although such particles are good non-conductors, the action of
the sulphuric acid electrolyte carbonizes them, giving them
conducting properties which tend to produce leakage.
[Illustration: FIGS. 1,159 to 1,161.—"Champion" electric light
equipment designed especially for use on launches, yachts, and
country residences. The outfit consists of three essential parts: 1,
a dynamo run by belt from main engine; 2, a storage battery, and 3, a
switchboard to regulate, measure and control the current.]
=Ques. How should the cells be assembled?=
Ans. In placing the plates or plate sections in the containing jars
or tanks, care should be taken to see that the supporting frame of
paraffined wood bears evenly on the bottom of the jar. If they do not,
wedges of paraffined wood should be placed under the frame, so as to
distribute the weight of the section equally. Each section should be
lowered gently into the jar until it rests fairly upon the frame, and
care should be taken to see that none of the plates have shifted, and
that the section is situated centrally in the jar, with a small clear
space all around.
=Ques. How should the cells be arranged?=
Ans. They should be so placed that the battery attendant can see the
edges of the plates and consequently the spaces between them at the
same time.
=Ques. Describe the method of connecting the cells.=
Ans. This is accomplished by means of solder, bolts and nuts, or
clamps, according to circumstances. The use of solder is not essential
if there be a good surface of the lead strip of one cell in contact
with that of the next, and provided these contact surfaces have been
well cleaned. Usually, the ends of the lead strips are turned up so
that the junction of two cells takes the form of an inverted T as shown
in fig. 1,162.
[Illustration: FIG. 1,162.—Two storage cells; view showing the
inverted T form of connection.]
=Ques. What precaution should be taken in joining the terminals of the
cells?=
Ans. The contact at the junctions should be very thorough, otherwise
they will become heated when a current is flowing, and it is desirable
that the connections should include as little lead strip in the circuit
as possible, thereby reducing the amount of useless resistance.
Brass or gun metal clamps may be kept clean by brushing them
over with melted paraffin after they have been screwed up
tightly. When thus treated they serve to indicate points of bad
contact by heat, generated at such points, when the current is
flowing, softening the paraffin and changing its normal color.
Vaseline and different kinds of anti-sulphuric acid varnishes,
or preparations that are not attacked by the electrolyte, may
also be used for this purpose. It is a good plan to color the
varnish with vermillion or lamp black and paint the positive
connections red and the negative connections black, and
also other parts of the installation for distinguishing the
polarities.
=Cell Connections.=—The cells may be connected together either
in series or parallel, or in parallel-series or series-parallel
combinations, according to the requirements, but in all cases it is
best to use the simplest arrangement practicable.
For instance: if the cells employed in an installation
requiring 110 volts, have only half the capacity required, and
55 cells give the desired voltage, then the number of cells
must be increased to 110, and theoretically the required number
of amperes hours at 110 volts may be obtained in one of two
ways: 1, by connecting the cells in pairs in parallel and then
coupling the pairs together in series, and 2, by arranging the
110 cells in two complete batteries of 55 cells each connected
in series, then coupling the two batteries in parallel.
The first method is quite impracticable, however, as the
slightest difference between the voltages of the two cells of
any pair will result in the one having the greater pressure
discharging into the other, thereby causing the entire battery
to quickly deteriorate.
NOTE.—_To determine the positive wire._ Without a voltmeter,
the positive terminal of the charging circuit can be determined
by attaching a piece of clean lead to each wire which is to be
connected to the battery, and immersing them, without touching
each other, in a glass or other insulating vessel containing
water to which is added a drop or two of sulphuric acid. After
the current has passed through the circuit for a short time,
the positive lead will commence to discolor, and, if left
long enough, will turn brown. Bubbles will arise from the two
terminals immersed, the larger and more frequent ones being
from the negative, the smaller ones from the positive.
NOTE.—_Method of disconnecting "National" cells._ There
are two methods of disconnecting the cells employing link
connectors. First a ⅝ inch bit or twist drill may be used,
boring down into the top of the posts about ¼ inch. The link
will then be loosened and can be removed. This leaves the link,
as well as the post, in good condition for reburning. Second
the link may be cut in the center. A flame should be played on
the top of the post, at the same time grasping the end of the
half link firmly with pliers. When the connection has become
warmed (care being taken not to melt the lead) the half link
can be twisted loose from the port. New links may be used if
desired in re-assembling the cells. It is not necessary to
remove the covers from the element, the links may be cut in the
center and the plates removed from the jars without removing
the links from the ports. The links can be afterwards reburned
together in the center. When the cells are equipped with "T" or
"L" straps, they should be cut apart with hack saw or chisel
midway between the cells, and in re-assembling, burned together
at this point.
=Battery Troubles.=—To successfully cope with faults in storage
batteries, there are two requisites: 1, a thorough knowledge of the
construction and principle of operation of the battery, and 2, a well
ordered procedure in looking for the source of trouble. The faults
which are usually encountered by those who operate storage batteries
are here given.
[Illustration: FIG. 1,163.—Arrangement of battery cells and stand.
A, cable lugs; B, bus bars; C, glass tanks; D, plate; E, glass
insulators; Q, vitrified brick; O, lead washers. Battery cells are
set up on stands; the one shown being built for a 100 ampere battery.
Larger sizes would, of course, require heavier stands, and if space be
limited, the cells may be set in rows, one above the other. However,
it is evidently much better to place the cells in single rows, where
they will be convenient for inspection and repairs or any work that has
to be done on them. There are several other ways of setting a battery,
one of which is to place the stringers on the floor, on vitrified
brick or some other insulator, and then place trays filled with sand
on the stringers, setting the cells in the trays on glass insulators.
The battery room should be dry, clean, well ventilated and free from
metal work, also neither too hot nor too cold. Too high a temperature
in the battery will shorten the life of the plates, and although there
is no danger of the battery freezing, a low temperature, while it is
maintained, reduces the capacity; otherwise cold has no ill effect on
the battery. A good temperature for the battery room is about 60° F.
A damp, dirty room is conductive to grounds and surface leakage, and
there is danger of impurities getting into the cells. If the room be
very damp the electrolyte may absorb enough moisture to cause the cells
to overflow. Strong floors are necessary to support a battery, as one
of a 100 ampere, 125 volt capacity weighs from 12 to 13 tons. A wood
floor may be used, but a cement floor is better, and a glazed vitrified
brick floor is better still. Wooden floors will rot quickly from the
acid, which is sure to get onto it more or less; a cement floor will be
disintegrated if too much acid get onto it. This kind of floor forms
a first class ground if there be any chance for one; the glazed brick
floor is not affected by the acid and is an insulator.]
=Short Circuiting.=—A form of derangement that may occasionally affect
storage batteries is short circuiting. It may be caused by some of the
active material—if the cell be of the pasted variety—scaling off and
dropping between the plates, or by an over collection of sediment in
the bottom of the cell.
Should the operator suspect trouble with his battery he may
discover a short circuited cell by the marked difference
in color of the plates or of the specific gravity of the
electrolyte, as compared with the other cells. No particular
damage will be caused, if the trouble be discovered and removed
before these symptoms become too marked.
If a foreign substance has become lodged between the plates, it
may be removed by a wood or glass instrument.
If some of the active material has scaled off, it may be forced
down to the bottom of the jar. If excessive sediment be found,
the jar and plates should be washed carefully, and reassembled.
A cell that has been short circuited may be disconnected from the
battery and charged and discharged several times separately which may
remedy the trouble.
=Ques. How are internal short circuits indicated?=
Ans. Short circuits in a cell are indicated by short capacity, low
voltage and low specific gravity, excessive heating and evaporation of
the electrolyte.
=Ques. How are internal short circuits located?=
Ans. If the trouble cannot be located by the eye, the battery should be
connected in series and discharged at the normal rate through suitable
resistance. If a suitable rheostat be not available, a water resistance
may be used.
This consists of a receptacle (which must not be of metal)
filled with very weak acid solution, or with salt water in
which are suspended two metal plates, which are connected by
wires through an ammeter. The current may be regulated by
altering the distance between the plates, or by varying the
strength of the solution. As the discharge progresses the
voltage will gradually decrease, and it should be frequently
read at the battery terminals; as soon as it shows a sudden
drop, the voltage of each cell should be read with a low
reading voltmeter.
While the readings are being taken, the discharge rate should
be kept constant and the discharge continued until the majority
of the cells read 1.70 volts; those reading less should be
noted. The discharge should be followed by a charge until the
cells which read 1.70 volts are up, then the low cells should
be cut out, examined, and the trouble remedied.
=Overdischarge: Buckling.=—On account of unequal expansion of the two
sides of a plate, or certain portions thereof, the strains thus set up
may distort it and cause it to assume a buckled shape, that is, bent so
one side is concave.
[Illustration: FIG. 1,164.—Method of straightening a buckled plate.
Buckling is caused by the unequal expansion of the plates which is due
to the sulphate lodging on the plates, thus preventing action taking
place at that point; and by excessive charging. If the plates be not
badly buckled, they can be placed between 2 boards and with a little
pressure, can be straightened out.]
Buckling is due always to over discharge on either the whole,
or some portion of the plate. Occasional buckling may occur
with too rapid charge and discharge.
=Sulphation of Plates.=—During discharge a storage cell deteriorates
on account of the formation of lead sulphate over the surface of the
plates. This lead sulphate is the product of the chemical combination
of active material with the electrolyte. It is a non-conductor, white
in color and of greater volume, in proportion than the active material.
When the discharge is over prolonged, sulphation is evidenced by the
electrodes becoming lighter in color, because of the sulphate which
lessens the active surface.
[Illustration: FIGS. 1,165 and 1,166.—Oil Insulator; fig. 1,165,
general view; fig. 1,166, sectional view. Whenever a number of open
cells are in use, unless precautions be taken, electrical leakage
between the cells invariably occurs. This leakage is due chiefly to the
semi-conducting nature of the thin layer of moisture which frequently
covers not only the glass containing cells, but the unimmersed parts of
the elements, and even the shelves on which the cells rest. To prevent
this waste of energy, the outside of the cells should occasionally be
well cleaned and thoroughly dried. A little vaseline or tallow may
then be rubbed over them to advantage. The shelves or supports for
the cells, should either be well varnished or coated with paraffin
wax. Electrical leakage is greatly reduced if each cell be mounted
on a glass or earthenware insulator, as shown in the illustrations.
The insulator here shown is in two parts and of a mushroom shape. The
lower cup contains a small quantity of some non-evaporating oil, and
as the conducted moisture cannot bridge across this, a nearly perfect
insulating medium is obtained. These insulators are made in various
sizes and may be obtained in earthenware or glass. Those made of glass
are found to give the best results.]
=Ques. Name some causes of sulphation.=
Ans. It is sometimes caused by a too weak or too strong acid solution,
but more generally by continued over discharging, or too rapid
discharging of the batteries, or by allowing them to remain uncharged
for long periods of time.
=Ques. What is the effect of sulphation?=
Ans. It tends to cause shedding of the active material, buckling
of plates, loss of capacity, increase of resistance and consequent
reduction of efficiency, and increase of temperature with flow of
current. A sufficient amount of lead peroxide and sponge lead must
be retained on the plates to reduce this resistance, otherwise the
charging current cannot flow through the active material and regenerate
the battery.
[Illustration: FIG. 1,167.—Illustrating method of placing plates in
glass jars.]
=Ques. What should be done in case of sulphation?=
Ans. Charge the battery below the maximum rate, necessarily prolonging
the charge, until the plates assume the proper color. This is a tedious
task, but it must not be hastened, as rapid charging will cause serious
buckling.
* * * * *
NOTE.—_How to destroy acid vapor in storage battery rooms_:
The best remedy is a good system of thorough and rapid
ventilation; failing this the evil effect of the acid may be
minimized by the fumes of a powerful alkali such as ammonia,
which will readily combine with the sulphuric acid to form
sulphate of ammonia, an inert and harmless salt. If the use
of liquid ammonia be objectionable, the granulated carbonate
of ammonia will do equally well. The ammonia fumes are best
obtained by placing dilute ammonia in shallow dishes, so that
an extensive evaporating surface is obtained. In the same way
the corroding dew which is so frequently deposited on the lugs
and connectors of storage battery elements may readily be
neutralized by the application of a solution of ammonia, or
even common washing soda. A good method of protecting metal
work in battery rooms is to smear it over evenly with vaseline.
The charging should be done at low rates. Discharge should not
be carried below 1.8 volts per cell, and the charging current
should be stopped when each cell shows 2.4 volts.
If the plates be in a very bad condition, a little of the white
sulphate deposit on each of the positive plates may be removed
with a stick, thus exposing a part of the good surface to the
action of the electrolyte.
If the positive plates cannot be restored to their proper color
as directed, it is cheaper to replace them by a new set, rather
than to attempt their recovery by means of reversals.
Electrical Data on "National" Cells
(Size of plate 4⅞" × 8⅝")
======================================+=======+=======+========+========
Number of Plates per cell | 5 | 7 | 9 | 11
——————————————————————————————————————+——————-+——————-+————————+————————
{for 4 hours |12 |18 | 24 | 30
Discharge in amperes {for 5 hours |10¼ |15¼ | 20½ | 25½
{for 6 hours | 9¼ |13¾ | 18½ | 23
| | | |
{at 4 hour rate|48 |72 | 96 |120
Ampere hour capacity {at 5 hour rate|51 |76 |102 |127
{at 6 hour rate|55 |83 |110 |138
| | | |
Outside measurements of rubber {Length| 1⅞ | 2⅝ | 3⅜ | 4-3/16
jar, in inches {Width | 5-5/16| 5-5/16| 5-5/16| 5-5/16
{Height|11¾ |11¾ | 11¾ | 11¾
| | | |
Weight of cell complete, in lbs |14¼ |19¼ | 24¼ | 29¾
| | | |
Weight of electrolyte, in lbs | 1 | 2 | 3½ | 5
——————————————————————————————————————+——————-+——————-+————————+————————
=Lack of Capacity.=—This is usually due to the clogging of the pores
in the plate with sulphate which is invisible because the surface of
the plate is maintained in proper condition but the interior portions
of the active material have not been thoroughly reduced. To correct
this condition, the battery should be given a prolonged overcharge at
low current rates, say about one fourth the normal 8 hour charging rate.
NOTE.—_Oxide of lead_, _litharge_, or _plumbic oxide_ is
sometimes found native as lead ochre, and may be artificially
made by heating the carbonate or nitrate. It is usually
prepared on a larger scale by heating the lead in air. When
the metal is only moderately heated, the oxide forms a yellow
powder which is known as massicot, but at a higher temperature
the oxide melts, and on cooling, it forms a brownish scaly
mass, which is called flake litharge. The scaly pieces are
afterwards ground between stones under water, forming buff
or levegated litharge. The litharge of commerce often has a
reddish yellow color, due to the presence of some of the red
oxide of lead, and frequently from one to three per cent. of
finely divided metallic lead is found mixed with it. When
heated to dull redness litharge assumes a dark brown color, and
becomes yellow again on cooling. At a bright red heat it fuses
and readily attacks clay crucibles, forming silicate of lead.
Litharge is a most powerful base, and has a strong tendency to
form basic salts. Hot solution of alkalies, as potash or soda,
readily dissolve it, and on cooling, it crystalizes out in the
form of beautiful pink crystals.
Falling off in the capacity may be caused by a dry cell, due
to a leaking jar; some or all of the cells may be in a state
of incomplete charge, due to the battery having been run too
low and not sufficiently charged; or the plates may be short
circuited, either by the sediment (deposit in the bottom of the
jar) getting up to the bottom of the plates or by something
that has fallen into the cell.
Electrical Data on "American" Cells
+————————+——————————————————————————————————————————-+
| Normal | Number of 30 volt Tungsten lamps that can |
|Capacity| be run with 16 cells in series for |
| | 2, 4, 6 or 8 hours |
+————————+——————————+——————————+——————————+——————————+
| Ampere | | | | |
| hours | 2 hours | 4 hours | 6 hours | 8 hours |
| 40 | 14 | 9 | 8 | 7 |
| 60 | 17 | 14 | 12 | 10 |
| 80 | 28 | 18 | 15 | 14 |
| 120 | 42 | 27 | 24 | 21 |
| 160 | 57 | 37 | 31 | 28 |
| 200 | 71 | 45 | 40 | 35 |
| 250 | 88 | 56 | 50 | 44 |
| 300 | 106 | 70 | 60 | 52 |
| 350 | 124 | 81 | 71 | 62 |
| 400 | 142 | 91 | 81 | 71 |
+————————+——————————+——————————+——————————+——————————+
[Illustration: FIG. 1,168.—"American" cell.]
=Ques. What action takes place when a battery stands idle for some
time?=
Ans. It loses part of its charge, due to local losses in the cells.
=Ques. How should batteries be treated, when used but occasionally?=
Ans. If a battery is not to be used for several days, it should first
be fully charged before standing; if it continue idle, a freshening
charge should be given every two weeks, continuing the charge when the
cells begin to gas freely.
=Ques. What should be done in case of lack of capacity?=
Ans. If the current consumption be normal, there may be poor
connections or trouble in the battery; there may be a dry cell, due to
a leaking jar; some or all of the cells may be in a state of incomplete
charge, due to the battery having been run too low and not sufficiently
charged, or the plates may be short circuited, either by the sediment
(deposit in the bottom of the jar) getting up to the bottom of the
plates or by something that has fallen into the cell.
Electrical Data on "Autex" Cells
(Standard plates; size, 5¾" x 8⅝")
+————————————————————————————————+————————+————————+————————+————————+
|Number of Plates | 7 | 9 | 11 | 13 |
+————————————————————————————————+————————+————————+————————+————————+
|Discharge in Amperes for 4 hours| 21 | 28 | 35 | 42 |
+————————————————————————————————+————————+————————+————————+————————+
| {Length | 2¾ | 3½ | 4¼ | 5 |
|Outside Measurements { +————+————+————+————+
| {Width | 6⅛ | 6⅛ | 6⅛ | 6⅛ |
|Rubber Jars in inches. { +————+————+————+————+
| {Height | 12⅜ | 12⅜ | 12⅜ | 12⅜ |
+————————————————————————————————+————————+————————+————————+————————+
| {Element | 15¾ | 20¼ | 24¼ | 29¾ |
| { +————————+————————+————————+————————+
|Weight in Pounds {Electrolyte | 4½ | 5 | 5¾ | 6¼ |
| { +————————+————————+————————+————————+
| {Complete Cell | 22 | 28 | 34¼ | 40½ |
+————————————————————————————————+————————+————————+————————+————————+
Electrical Data on "Autex" Cells(continued)
(Standard plates; size, 5¾" x 8⅝")
+————————————————————————————————+————————+————————+————————+————————+
|Number of Plates | 15 | 17 | 19 | 21 |
+————————————————————————————————+————————+————————+————————+————————+
|Discharge in Amperes for 4 hours| 49 | 56 | 63 | 70 |
+————————————————————————————————+————————+————————+————————+————————+
| {Length | 5¾ | 6½ | 7¼ | 8 |
|Outside Measurements { +————————+————————+————————+————————+
| {Width | 6⅛ | 6⅛ | 6⅛ | 6⅛ |
|Rubber Jars in inches. { +————————+————————+————————+————————+
| {Height | 12⅜ | 12⅜ | 12⅜ | 12⅜ |
+————————————————————————————————+————————+————————+————————+————————+
| {Element | 34 | 38½ | 43 | 47½ |
| { +————————+————————+————————+————————+
|Weight in Pounds {Electrolyte | 7 | 7¾ | 8½ | 9¾ |
| { +————————+————————+————————+————————+
| {Complete Cell | 47 | 53¼ | 59½ | 66 |
+————————————————————————————————+————————+————————+————————+————————+
NOTE.—_Peroxide of lead, pure oxide or plumbic dioxide_ is the
true active material in all forms of lead storage cell. This
lead salt is found native as the mineral plattnerite. It is
a heavy lead ore, forming black, lustrous, six sided prisms.
It may be prepared from the red oxide by boiling it in fine
powder, with nitric acid diluted with five parts of water, or
by treating the carbonate when suspended in water with a stream
of chlorine gas, and then thoroughly washing and drying it. It
is reduced to a lower oxide on heating or by exposure to bright
sunlight. This salt readily imparts oxygen to other substances;
it becomes heated to redness when thrown into sulphuric
dioxide, and takes fire when triturated with sulphur—hence
this oxide is a common ingredient in lucifer match composition.
When used in primary or secondary batteries it readily imparts
its oxygen to nascent hydrogen, forming water, and thus it
acts as a powerful depolarizer. When robbed of its oxygen,
it readily becomes reoxidized, if subjected to the action of
nascent oxygen liberated by the electrolytic decomposition of
water.
If the trouble cannot be located by the eye, connect the
battery in series, and discharge it at the normal rate, through
suitable resistance. If a suitable rheostat be not available, a
water resistance may be used.
This consists of a receptacle (which must not be of metal)
filled with very weak acid solution or salt water in which
are suspended two metal plates, which are connected, by wires
through an ammeter.
Electrical Data on "Autex" Cells
(Light weight plates; size, 5¾" × 8⅝")
——————————————————————————+——————————+————————-+——————————+————————+————————-+
Number of Plates | 7 | 9 | 11 | 13 | 15 |
——————————————————————————+——————————+————————-+——————————+————————+————————-+
Discharge in Amperes for | | | | | |
5 hours | 15¾ | 21 | 26¼ | 31½ | 36¾ |
——————————————————————————+——————————+————————-+——————————+————————+————————-+
Outside {Length | 1-29/32 | 2-7/16 | 3-31/32 | 3½ | 4-⅟32 |
Measurements { +——————————+————————-+——————————+————————+————————-+
{Width | 6⅛ | 6⅛ | 6⅛ | 6⅛ | 6⅛ |
Rubber { +——————————+————————-+——————————+————————+————————-+
Jars in in. {Height | 12⅜ | 12⅜ | 12⅜ | 12⅜ | 12⅜ |
——————————————————————————+——————————+————————-+——————————+————————+————————-+
Weight {Element | 11½ | 14¾ | 18 | 21¼ | 24½ |
in { +——————————+————————-+——————————+————————+————————-+
Pounds {Electrolyte | 2¼ | 2½ | 3 | 3¾ | 4¼ |
{ +——————————+————————-+——————————+————————+————————-+
{Comp. Cell | 15¾ | 20 | 24¼ | 28½ | 33¼ |
——————————————————————————+——————————+————————-+——————————+————————+————————-+
——————————————————————————+——————————+————————-+——————————+————————+————————-+
Number of Plates | 17 | 19 | 21 | 23 | 25 |
——————————————————————————+——————————+————————-+——————————+————————+————————-+
Discharge in Amperes for | | | | | |
5 hours | 42 | 47¼ | 52½ | 57¾ | 63 |
——————————————————————————+——————————+————————-+——————————+————————+————————-+
Outside {Length | 4-9/16 | 5-3/32 | 5⅜ | 6-5/32| 6-11/16 |
Measurements { +——————————+————————-+——————————+————————+————————-+
{Width | 6⅛ | 6⅛ | 6⅛ | 6⅛ | 6⅛ |
Rubber { +——————————+————————-+——————————+————————+————————-+
Jars in in.|{Height | 12⅜ | 12⅜ | 12⅜ | 12⅜ |12⅜ |
——————————————————————————+——————————+————————-+——————————+————————+————————-+
Weight {Element | 27¾ | 31 | 34¼ | 37¼ | 40½ |
in { +——————————+————————-+——————————+————————+————————-+
Pounds {Electrolyte | 4¼ | 5½ | 6 | 6¾ | 7¼ |
{ +——————————+————————-+——————————+————————+————————-+
{Comp. Cell | 38 | 42 | 46¼ | 51½ | 56 |
——————————————————————————+——————————+————————-+——————————+————————+————————-+
The current may be regulated by altering the distance between
the plates or by varying the strength of the solution. As the
discharge progresses, the voltage will gradually decrease and
it should be frequently read at the battery terminals. When it
shows a sudden drop, the voltage of each cell should be read
with a low reading voltmeter.
While the readings are being taken, the discharge rate should
be kept constant and the discharge continued until the majority
of the cells read 1.70 volts; those reading less should be
noted. The discharge should be followed by a charge until the
cells which read 1.70 volts are up; then the low cells should
be cut out, examined and the trouble remedied.
NOTE.—_How to prevent lead poisoning._ Workmen employed in
the manufacture of lead or lead salts are always liable to
lead poisoning, both by inhaling the dust and by contact of
the materials with the hands. Various preventives for this
have been employed, and of these, the most simple seems to be
a careful washing of the hands in petroleum. It is said that
three washings a day are sufficient to prevent all serious
danger of poisoning. The benzole in the petroleum appears
to scour the skin and remove the loose lead dust, and the
fatty substance in the oil fills up the pores of the skin
and prevents the absorption of the deleterious salts. The
employment of petroleum has given such good results that it has
been proposed to use this material as a guard against poisoning
in other industries where the salts of copper or mercury are
employed.
=Ques. What causes low specific gravity when there are no short
circuits?=
Ans. 1, sloppage or a leaky jar (the loss having been replaced with
water alone), 2, insufficient charge, 3, over discharge, or 4, a
combination of these abuses. Any of these mean that there is acid in
combination with the plates.
In this case the acid should be brought out into the
electrolyte by a long charge at a quarter of the normal
discharge rate.
[Illustration: FIGS. 1,169 and 1,170.—The "National" storage battery;
views showing methods of assembling cells. Fig 1,169, end assembling;
fig 1,170, side assembling.]
=Ques. How should weak cells be treated?=
Ans. They should be grouped by themselves and charged as a separate
battery, care being taken that the positive strap of one cell, is
connected to the negative strap of the adjoining cell and that the
charging connections are properly made. If there be not sufficient
resistance in the charging rheostat to reduce the current to the proper
point, a water resistance should be used.
NOTE.—_Pole testing paper._ Make a thin solution of white
starch and soak strips of thin white blotting paper in it,
and set aside in a clean, dry place to dry. Dissolve ½ oz.
of potassium iodide in one pint of water. Immerse the strips
in the solution for a few seconds and again dry. This paper,
when moistened and used in the usual way, turns violet at the
positive pole.
While a cell is being treated, when possible, the cover should
be removed (if sealed, the compound can be loosened by using a
hot putty knife).
[Illustration: FIGS. 1,171 to 1,177.—"National" battery bolt connector
and parts. The connector is equipped with grease cups and antimonious
lead washers.]
=Disconnecting Cells.=—The best method of disconnecting cells
assembled with pillar straps, for the purpose of replacing broken jars,
cleaning or taking out of commission, is to use a five-eighth inch
twist drill, in a carpenter's brace, boring down into the top of the
pillar about one-quarter inch; then pull off the connector sleeve from
the pillar. By following this method, all parts may be used again.
When cells are equipped with top straps, the straps should be
cut with a sharp knife or chisel midway between the cells.
=Taking Batteries out of Commission.=—Where a battery is to be out of
service for several months, and it is not convenient to give it the
freshening charge every two weeks, it should be taken out of commission.
COMPARISON OF THE BAUMÉ AND SPECIFIC GRAVITY
SCALES AT 60° FAHRENHEIT
+————————-+——————————+————————-+——————————+————————-+——————————+————————-+——————————+
|_Degrees_|_Specific_|_Degrees_|_Specific_|_Degrees_|_Specific_|_Degrees_|_Specific_|
| _Baume_ |_Gravity_ | _Baume_ |_Gravity_ | _Baume_ |_Gravity_ | _Baume_ |_Gravity_ |
+————————-+——————————+————————-+——————————+————————-+——————————+————————-+——————————+
| 0 | 1.000 | 17 | 1.133 | 34 | 1.306 | 51 | 1.542 |
| 1 | 1.007 | 18 | 1.142 | 35 | 1.318 | 52 | 1.559 |
| 2 | 1.014 | 19 | 1.151 | 36 | 1.330 | 53 | 1.576 |
| 3 | 1.021 | 20 | 1.160 | 37 | 1.342 | 54 | 1.593 |
| 4 | 1.028 | 21 | 1.169 | 38 | 1.355 | 55 | 1.611 |
| 5 | 1.036 | 22 | 1.179 | 39 | 1.368 | 56 | 1.629 |
| 6 | 1.043 | 23 | 1.188 | 40 | 1.381 | 57 | 1.648 |
| 7 | 1.051 | 24 | 1.198 | 41 | 1.394 | 58 | 1.666 |
| 8 | 1.058 | 25 | 1.208 | 42 | 1.408 | 59 | 1.686 |
| 9 | 1.066 | 26 | 1.218 | 43 | 1.421 | 60 | 1.707 |
| 10 | 1.074 | 27 | 1.229 | 44 | 1.436 | 61 | 1.726 |
| 11 | 1.082 | 28 | 1.239 | 45 | 1.450 | 62 | 1.747 |
| 12 | 1.090 | 29 | 1.250 | 46 | 1.465 | 63 | 1.768 |
| 13 | 1.098 | 30 | 1.261 | 47 | 1.479 | 64 | 1.790 |
| 14 | 1.107 | 31 | 1.272 | 48 | 1.495 | 65 | 1.812 |
| 15 | 1.115 | 32 | 1.283 | 49 | 1.510 | 66 | 1.835 |
| 16 | 1.124 | 33 | 1.295 | 50 | 1.526 | | |
+————————-+——————————+————————-+——————————+————————-+——————————+————————-+——————————+
NOTE.—The characteristic properties of concentrated sulphuric
acid are very marked. Its freedom from odor, oily appearance,
and its great weight, distinguish it from other liquids. The
pure concentrated commercial acid has a density which usually
reaches 1.842, and its boiling point is about 640° F. The
absolutely pure acid is perfectly colorless, but usually even
that used in laboratories has a peculiar grayish color, due to
slight traces of organic matter. Sulphuric acid is exceedingly
hydroscopic, and when exposed to the air it rapidly increases
in bulk, owing to absorption of atmospheric moisture.
NOTE.—Clamps not made of metal similar to that of the
connecting strips, frequently give trouble from the galvanic
action due to the contact of dissimilar metals in the presence
of moisture which causes the destruction of either the
connecting strip or the clamp. Such troubles can be avoided
by placing a thin strip of sheet zinc between the lead strip
and the clamp. Under these circumstances the zinc will crumble
away, and can be replaced without much inconvenience and very
little expense, while the clamps and connecting strips will
remain uninjured.
Strength of Dilute Sulphuric Acid
of
Different Densities at 59° Fahr.
+————————————————+——————————+————————————————+——————————+
| Per cent. | Specific | Per cent. | Specific |
| of | | of | |
| Sulphuric Acid | Gravity | Sulphuric Acid | Gravity |
+————————————————+——————————+————————————————+——————————+
| 100 | 1.842 | 23 | 1.167 |
| 40 | 1.306 | 22 | 1.159 |
| 31 | 1.231 | 21 | 1.151 |
| 30 | 1.223 | 20 | 1.144 |
| 29 | 1.215 | 19 | 1.136 |
| 28 | 1.206 | 18 | 1.129 |
| 27 | 1.198 | 17 | 1.121 |
| 26 | 1.190 | 16 | 1.116 |
| 25 | 1.172 | 15 | 1.106 |
| 24 | 1.174 | 14 | 1.098 |
+————————————————+——————————+————————————————+——————————+
=Ques. Describe the method of taking a battery out of commission.=
Ans. The battery is charged in the usual manner, until the specific
gravity of the electrolyte of every cell has stopped rising over a
period of one hour (if there be any low cells, due to short circuits
or other cause, they should be put in condition before the charge is
started, so that they will receive the full benefit of it). The cells
may now be disconnected and covers and elements removed from the jars,
(if sealed, the compound is loosened with a hot putty knife). The
elements are placed on their sides with the plates slightly spread
apart at the bottom, the separators withdrawn, and the positive and
negative groups pulled apart. The electrolyte is washed off with a
gentle stream of water and the plates allowed to drain and dry.[7] The
positive plates are ready to be put away. When dry, the negatives are
completely immersed in electrolyte (of about 1.275 specific gravity),
and allowed to soak for three or four hours. The jars may be used for
this purpose. After rinsing and drying, they are ready to be put away;
wash also the rubber separators.
[7] NOTE.—If the active material in the negative plates extend beyond
the ribs of the grid (the supporting frame), it should be at once
pressed back into place, care being taken to prevent the plates drying
before this is done. The most suitable and convenient method for
pressing, is to place between the plates smooth boards of a thickness
equal to the distance between the plates and then put the groups under
pressure.
Wood separators, after having been in service, will not stand
much handling and had better be thrown away. If it be thought
worth while to keep them, they must be immersed in water or
weak electrolyte, and in re-assembling, the electrolyte must be
put into the cells immediately, as wet wood separators must not
stand exposed to the air.
[Illustration: FIG. 1,178.—The "Witham" charging board, for charging
from any electric outlet on a direct current system. The instrument
shows the direction of the current, and the candle power of the lamps
used as resistance indicates approximately the strength of the current
passing. Operation: From any convenient electric light fitting remove
one of the lamps, replacing it by the plug attached to the flexible
cord. Screw the lamp into one of the sockets on the charging board.
Connect a wire to each binding post, and before joining up to the
battery, hold the ends of the two wires together. The lamp will then
light up and the indicator needle will point to that binding post which
must be connected to the positive (+) terminal of the battery. The
other binding post must, of course, be connected to the negative (-) of
the battery. The charging current can be increased by inserting another
lamp into the second socket on the charging board and by using lamps of
higher candle power. If, when the lamp lights up, the indicator needle
do not point to one of the binding posts, but retain its position
midway, then the current is an alternating one and will not charge the
battery.]
=Ques. What precaution should be taken with the jars?=
Ans. They should be thoroughly cleaned with fresh water, no sediment
being allowed to remain.
=Putting Batteries into Commission.=—When re-assembling a battery, it
should be treated in the same manner as if it were new and the regular
instructions for assembling and putting a new battery into commission
followed.
=Cleaning Jars.=—The jars should be thoroughly cleaned with fresh
water, no sediment being allowed to remain.
Table of Voltage Change as Affected by Discharge Rate[8]
[8] NOTE.—The voltage increase or decrease with change in current is
practically constant in a given type of cell for any size of cell when
the current is referred to a given time rate of charge or discharge;
that is, the drop in a large cell or in a small cell, when each is
discharged at its four, six or eight hour rate, will be the same. The
drop varies somewhat for the condition of the battery charge. For
batteries which are one-third discharged, the temperature 60° Fahr.,
and plates in good condition, the changes in pressure which may be
expected between open circuit voltage and the voltage on charge or
discharge are given in the above table.
8 hour rate .05 volt
6 " " .065 "
4 " " .09 "
3 " " .11 "
2 " " .14 "
1½ " " .18 "
1 " " .21 "
=Condensed Rules for the Proper Care of Batteries.=—The following
general instructions should be followed in the care and maintenance of
batteries:
1. A battery must always be charged with "direct" current and
in the right direction.
2. Be careful to charge at the proper rates and to give the
right amount of charge; do not undercharge or overcharge to an
excessive degree.
3. _Do not bring a naked flame near the battery while charging
or immediately afterwards._
4. Do not overdischarge.
5. Do not allow the battery to stand completely discharged.
6. Voltage readings should be taken only when the battery is
charging or discharging; if taken when the battery is standing
idle they are of little or no value.
7. Do not allow the battery temperature to exceed 110° Fahr.
8. Keep the electrolyte at the proper height above the top
of the plates and at the proper specific gravity. Use only
pure water to replace loss by evaporation. In preparing the
electrolyte _never pour water into the acid_.
9. Keep the cells free from dirt and all foreign substances,
both solid and liquid.
10. Keep the battery and all connections clean; keep all bolted
connections tight.
11. If there be lack of capacity in a battery, due to low
cells, do not delay in locating and bringing them back to
condition.
12. Do not allow sediment to get up to the plates.