Chapter XLIV: Storage Batteries (2)

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.

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.

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.

=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.

=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.

=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.

=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.

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.

=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.

=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 |
+————————+——————————+——————————+——————————+——————————+

=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.

=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).

=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.

=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.