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The Automobile Storage Battery - Its Care And Repair
by O. A. Witte
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Sharpen the carbon to a pencil point, and adjust its position so that it projects from the holder about one inch. Occasionally plunge the holder and hot carbon in a pail of water to prevent carbon from overheating. After a short time, a scale will form on the surface of the carbon, and this should be scraped off with a knife or file.

In burning in a connector, first melt the lead of the post and connector before adding the burning lead. Keep the carbon point moving over all parts to be joined, in order to insure a perfectly welded joint.

9. Illuminating Gas and Compressed Air. This is the slowest method of any. Pump equipment is required, and this method should not be used unless none of the other methods is available.

The selection of the burning apparatus will depend upon individual conditions as well as prices, and the apparatus selected should be one as near the beginning of the foregoing list as possible. Directions for the manipulation of the apparatus are given by the manufacturers.

The most convenient arrangement for the lead burning outfit is to run pipes from one end of the work bench to the other, just below the center shelf. Then set the gas tanks at one end of the bench and connect them to the pipes. At convenient intervals have outlets for attaching the hoses leading to the torch.

EQUIPMENT FOR HANDLING SEALING COMPOUND

(a) Stove. Where city gas is available, a two or three burner gas stove or hot-plate should be used. Where there is no gas supply, the most satisfactory is perhaps an oil stove. It is now possible to get an odorless oil stove which gives a hot smokeless flame which is very satisfactory. In the winter, if a coal stove is used to heat the shop, the stove may also be used for heating the sealing compound, but it will be more difficult to keep the temperature low enough to prevent burning the compound.

(b) Pot or Kettle. An iron kettle is suitable for use in heating compound. Special kettles, some of which are non-metallic, are on the market, and may be obtained from the jobbers.

(c) An iron ladle should be obtained for dipping up compound, and for pouring compound when sealing a battery. Figure 81 shows a convenient form of ladle which has a pouring hole in the bottom. A taper pin, which is raised by the extra handle allows a very fine stream of compound to be poured.

The exact size of the ladle is not important, but one which is too heavy to be held in one hand should not be used.

(d) Several old coffee pots are convenient, and save much time in sealing batteries.

Sealing compound is a combination of heavy residues produced by the fractional distillation of petroleum. It is not all alike-that accepted for factory use and distribution to Service Stations must usually conform to rigid specifications laid down by the testing laboratories governing exact degrees of brittleness, elongation, strength and melting point. For these qualities it is dependent upon certain volatile oils which may be driven off from the compound if the temperature of the molten mass is raised above the comparatively low points where some of these oils begin to volatilize off as gaseous vapor or smoke.

Compound from which certain of these valuable constituent oils have been driven off or "burned out" through overheating is recognized through too great BRITTLENESS and SHRINKAGE on cooling, causing "CRACKED COMPOUND" with all of its attending difficulties.

[Fig. 81 Pouring ladle]

Do not put too much cold compound in the kettle to begin with. It is not advisable to carry much more molten compound in the kettle at any time than can easily be dipped out-cold compound may be added during the day as needed. When there is considerable cold compound in the kettle, and the heating flame is applied, the lower bottom part of the mass next to the surface of the iron is brought to a melting point first-heat must be conveyed from this already hot part of the compound upward throughout the whole mass-so that before the top part of it is brought to a molten condition the lower inside layers are very hot indeed. If there is too much in the kettle these lower layers are necessarily raised in temperature beyond the point where they lose some of their volatile oils-they are "burned" before the whole mass of compound can be brought to a molten state.

Do not use too large a heating flame under the kettle for the same reasons. A flame turned on "full blast" will certainly "burn" the bottom layers before the succeeding layers above are brought to the fusion point. USE A SLOW FLAME and TAKE TIME IN MELTING UP THE COMPOUND. It PAYS in the resulting jobs.

The more compound is heated, the thinner it becomes—it should never be allowed to become so hot that it flows too freely—it should never exceed the viscosity of medium molasses. It should flow freely enough to run in all narrow spaces but NOT freely enough to flow THROUGH them before it cools.

Stir the kettle frequently during the day. It is advisable about once a week to work as much compound out of the kettle as possible, empty that still remaining, clean the kettle out, and start with fresh compound.

NEVER USE OLD COMPOUND OVER AGAIN—that is, do not throw compound that has been dug out of used batteries into the kettle with the new compound. The old compound is no doubt acid soaked, and this acid will work through the whole molten mass, making a satisfactory job a very doubtful matter indeed.

Cold weather hardens sealing compound, of course, and renders it somewhat brittle and liable to crack. This tendency could be overcome by using a softer compound, but, on the other hand, compound so soft that it would have no tendency to crack in cold weather would be so soft in warm weather that it would fail to hold the assembly with the necessary firmness and security. It is far better policy to run the risk of developing a few cracks in the winter than a loose assembly in summer. Surface cracks developed in cold weather may be easily remedied by stripping off the compound around the crack with a heated tool, flashing with the torch and quickly re-sealing according to the above directions.

It is not practical to work any oil agent, such as paraffin or castor oil, into the compound in an effort to soften it for use in cold weather.

SHELVING AND RACKS

The essential things about shelving in a battery shop are, that it must be covered with acid-proof paint, and must be made of heavy lumber if it is to carry complete batteries. Figure 82 shows the heavy shelving required in a stock-room, while Figure 83 shows the lighter shelving which may be used for parts, such as jars, cases, extra plates, and so on.

[Fig. 82]

Fig. 82. Typical Stockroom, Showing Heavy Shelving Necessary for Storing Batteries.

Figures 84 and 85 show two receiving racks for batteries which come in for repairs. In many shops batteries are set on the floor while waiting for repairs. If there is plenty of floor space, this practice is not objectionable. In any case, however, it improves the looks of the shop, and makes a better impression on the customer to have racks to receive such batteries. Note that the shelves are arranged so as to permit acid to drain off. Batteries often come in with wet, leaky cases, and this shelf construction is suitable for such batteries.

The racks shown in Figures 86 and 87 are for repaired batteries, new batteries, rental batteries, batteries in dry storage, and for any batteries which do not have wet leaky cases.

Figures 88 and 89 show racks suitable for new batteries which have been shipped filled with electrolyte, batteries in "wet" or "live" storage, rental batteries, and so on. Note that these racks are provided with charging circuits so that the batteries may be given a low charge without removing them from the racks. Note also that the shelves are spaced two feet apart so as to be able to take hydrometer readings, voltage readings, add water, and so on, without removing the batteries from the racks.

BINS

Figure 90 gives the dimensions for equipment bins suitable for covers, terminals, inter-cell connectors, jars, cases, and various other parts. These bins can be made with any desired number of sections, and additional sections built as they are needed.

[Fig. 83]

Fig. 83. Corner of Workshop, Showing Lead Burning Outfit, Workbench and Vises.

[Fig. 84 Working drawing of a 6-foot receiving rack]

[Fig. 85 Working drawing of a 12-foot receiving rack]

[Fig. 86 Working drawing of an 8-foot rack for repaired batteries, new batteries, rental batteries, batteries in dry storage, etc.]

[Fig. 87 Working drawing of a 16-foot rack for repaired batteries, new batteries, rental batteries, batteries in dry storage, etc.]



[Fig. 88 Working drawing of a 16-foot rack suitable for new batteries (shipped filled and fully charged), batteries in "wet" storage, rental batteries, etc.]

[Fig. 88b End view of rack in Fig. 88]

[Fig. 89 Working drawing of a 12-foot rack suitable for new batteries (shipped filled and fully charged), batteries in "wet" storage, rental batteries, etc.]

[Fig. 89b End view of rack in Fig. 89]

[Fig. 90 Working drawing of bins suitable for battery parts]

BATTERY STEAMER

Steaming is the most satisfactory method of softening sealing compound, making covers and jars limp and pliable. An open flame should never be used for this work, as the temperature of the flame is too high and there is danger of burning jars and covers and making them worthless. With steam, it is impossible to damage sealing compound or rubber parts.

A soft flame from a lead burning torch is used to dry out the channels in the covers before sealing, and is run over the compound quickly to make the compound flow evenly and unite with the jars and covers. But in such work the flame is used for only a few seconds and is not applied long enough to do any damage.

With a steaming outfit, it is also possible to distill water for use in mixing electrolyte and replacing evaporation in the cells. The only additional equipment needed is a condenser to condense the steam into water.

[Fig. 91]

Fig. 91. Battery Steamer, with Steam Hose for Each Cell

[Fig. 92 Condenser for use with battery steamer]

Figure 91 shows a steaming outfit mounted on a wall, and shows the rubber tube connections between the several parts. The boiler is set on the stove, water being supplied from the water supply tank which is hung above the boiler to obtain gravity feed. The water supply tank is open at the top, and is filled every morning with faucet water. This tank is suitable for any shop, even though a city water supply is available. A water pipe from the city lines may be run to a point immediately above the tank and a faucet or valve attached. Where there is no city water supply, the tank may, of course, be filled with a pail or pitcher.

The boiler is equipped with a float operated valve which maintains a one to one and one-half inch depth of water. As the water boils away, the float lowers slightly and allows water to enter the boiler. In this way, the water is maintained at the proper level at all times. A manifold is fitted to the boiler and has six openings to which lengths of rubber tubing are attached. These tubes are inserted in the vent holes of the battery which is to be steamed. Any number of the steam outlets may be opened by drawing out the manifold plunger valve to the proper point. When distilling water, a tube is attached to one of the steam outlets as shown, and connected to the condenser as shown. A bottle is placed under the distilled water outlet to collect the distilled water.

Cooling water enters the condenser through the tubing shown attached to the condenser at the lower right-hand edge. The other end of this tube is attached to the water faucet, or other cooling water supply. The cooling water outlet is shown at the lower left hand edge of the condenser. The cooling water inlet and outlet are shown in Figure 92.

If there is no city water supply, a ten or twenty gallon tank may be mounted above the condenser and attached by means of a rubber tube to the cooling water inlet shown at the lower right hand edge of the condenser in Figure 92. A similar tank is placed under the cooling water outlet. The upper tank is then filled with water. When the water has run out of the upper tank through the condenser and into the lower tank, it is poured back into the upper tank. In this way a steady supply of cooling water is obtained.

[Fig. 93 Steaming box in which entire battery is set]

Another type of steamer uses a steaming box, Figure 93. The battery is placed in the box and steam is sent in through the cover. The boiler has only one steam outlet, and this is connected to the box by means of a hose.

[Fig. 94 Special bench for battery steamer]

If desired, a special bench may be made for the steaming outfit, as shown in Figure 94.

The other tools needed for opening batteries, as given in the list on page 97 are standard articles, and may be obtained at any hardware store, except the terminal tongs, which should be purchased from a battery supply house.

[Fig. 95 Battery terminal tongs]

Figure 95 illustrates the use of terminal tongs. Battery terminals usually stick so tight that they must be forced out with pliers or other tools. Here is shown a pair of tongs that makes easy work of the job. One end has a fork and the other is shaped to come between the fork. It is placed on the battery terminal, as shown, and when the handles are brought together the terminal attached to the battery lead is forced out without marring any of the parts.

EQUIPMENT FOR LEAD BURNING (WELDING)

Plate Burning Rack

The plates which compose a "group" are joined to the plate connecting strap to which the post is attached. The plates are "burned" to the strap, and this must be done in such a manner that the plates are absolutely parallel, that the distance between plates is correct, and that the top surface of the strap is at right angles to the surface of the plates. These conditions are necessary in order that the positive and negative groups may mesh properly, that the complete element, consisting of the plates and separators may fit in the jar properly, and that the cell covers may fit over the posts easily.

[Fig. 96]

Fig. 96. Universal Plate Burning Rack. Will Hold Three Groups of Plates at One Time. Designed for Standard and Special Plates

In order to secure these conditions, plates that are to be burned to the strap are set in a "burning rack," shown in Figs. 96 and 97, which consists mainly of a base upon which the plate rest, and a slotted bar into which the lugs on the plates fit. The distance between successive slots is equal to the correct distance between the plates of the group. An improved form of burning rack has a wooden base which has slots along the side. The plates are set into these slots and are thus held in the correct position at both top and bottom.

[Fig. 97 Plate burning rack for standard 1/8 inch, and thin plates]

Fig. 97 shows a rack for use with 1/8 inch and 7-64 inch plates. Fig. 96 shows a "Universal" rack which may be used with both the 1/8 and 7-64 inch plates, and also many special plates.

The guide-bar, or "comb," E, has slots along two sides, the base having corresponding slots, as shown. To accommodate different sized plates, the comb may be raised or lowered, and the uprights may be moved back and forth in two slots, one of which is shown at F. In using this rack, the plates are set in position, with their lower edges in the slots of the base, and their lugs in the slots in the comb. The plates are in this way held at opposite corners, and are absolutely straight and parallel.

Special fittings are provided to simplify the work of burning. A bar, D, fits along the edge of the comb, and holds the lugs of the plates firmly in the slots. This bar is movable to any part of the comb, being held by two spring clips, C. Two bars, A and B, which are adjustable, make a form around the plate lugs which will prevent the hot lead from running off while burning in the plates.

Instructions for burning on plates are given on page 217.

The triangular scraper, steel wire brush, coarse files and smoked or blue glasses are all standard articles and may be obtained from any supply house. The burning collars are made of iron, and are set over the end of inter-cell connectors when burning these to the posts, see Figure 98. Experienced repairmen generally do not use them, but those who have trouble with the whole end of the connector melting and the lead running off should use collars to hold in the lead.

[Fig. 98 Burning collars]

The Burning Lead Mould

In every shop there is an accumulation of scrap lead from post drillings, old connecting straps, old plate straps, etc. These should be kept in a special box provided for that purpose, and when a sufficient amount has accumulated, the lead should be melted and run off into moulds for making burning-lead.

The Burning Lead Mould is designed to be used for this purpose. As shown in Fig. 99, the mould consists of a sheet iron form which has been pressed into six troughs or grooves into which the melted lead is poured. This sheet iron form is conveniently mounted on a block of wood which has a handle at one end, making it possible to hold the mould while hot without danger of being burned. A sheet of asbestos separates the iron form from the wood, thus protecting the wood from the heat of the melted lead. A hole is drilled in the end of the handle to permit the mould being hung on a nail when not in use. The grooves in the iron form will produce bars of burning lead 15 inches long, 5-16 inch thick, 3/8 inch wide at the top, and 1/4 inch wide at the bottom.

[Fig. 99]

Fig. 99. Burning-Lead Moulds, and Burning Sticks Cast in Them

The advantage of this type of Burning Lead Mould over a cast iron mould is obvious. The form, being made of sheet iron, heats up very quickly, and absorbs only a very small amount of heat from the melted lead. The cast-iron mould, on the other hand, takes so much heat from the melted lead that the latter cools very quickly, and is hard to handle.

An iron pot that will hold at least ten pounds of molten lead should be used in melting up lead scraps for burning sticks.

When the metal has become soft enough to stir with a clean pine stick skim off the dross. Continue heating metal until slightly yellow on top.

With a paddle or ladle drop in a cleaning compound of equal parts of powdered rosin, borax and flower of sulphur. Use a teaspoonful for a ten-pound melting and make sure the compound is perfectly dry.

Stir a little and if metal is at proper heat there will be a flare, flash or a little burning. A sort of tinfoil popcorn effect will be noticed floating on top of the metal. Stir until this melts down. Have your ladle hot and skim off soft particles. Dust the mould with mould compound, a powder which makes the lead fill the entire grooves, and not become cool before it does.

When everything is ready, fill the ladle and pour the lead into one of the grooves. Hold the ladle above one end of the groove while pouring, and do not move it along the groove. Fill the other grooves in a similar manner.

Post Builders. These are moulds which are set over the stumps of posts which have been drilled short in removing the inter-cell connectors. Lead is then melted in with a burning flame to build the post up to the proper height. Figure 100 shows a set of post-builders, and Figure 101 illustrates their use.

[Fig. 100 Set of post builders]

[Fig. 101 Illustrating use of post builders]

EQUIPMENT FOR GENERAL WORK ON CONNECTORS AND TERMINALS

Moulds for Casting Inter-Cell Connectors, Terminals, Terminal Screws, Taper Lugs, Plate Straps, Etc.

Figure 102 shows a plate strap mould with which three straps and posts may be cast in one minute. It has a sliding movable tooth rack for casting an odd or even number of teeth on the strap.

[Fig. 102 Plate strap mould]

Figure 103 shows a Link Combination Mould which casts five inter-cell connectors for use on standard 7, 9, 11, 13 and 15 plate batteries, four end connectors (two Dodge tapers, and standard tapers, negative and positive), one end connector with 3/8 inch cable used on 12 volt Maxwell battery and on all other cars a wire cable, and one small wire to connect with end post on batteries requiring direct connection. It also casts two post support rings to fit standard size rubber covers and to fit posts cast with plate strap mould, and two washers which are often needed when installing needed when installing new or rental batteries.

[Fig. 103 and Fig. 104: Link combination mould, and castings made in it]

Figure 104 shows the parts which may be made with this mould.

[Fig. 105 Cell connector mould]

[Fig. 106 Production type strap mould]

Figure 105 shows a cell connector mould which casts practically all the cell connectors used on standard 7, 9, 11, 13 and 15 plate batteries. This mould is similar to the Link Combination Mould shown in Figure 103.

[Fig. 107 Indexing device for strap mould]

[Fig. 108 Castings made in strap mould]

Figure 106 shows a production type strap mould which is designed to be used by large battery shops. Forty-two styles of straps are, cast by this mould. This mould has an indexing device as shown in Figure 107, which is adjusted by means of a screw for moulding the straps for any number of plates from seven to nineteen. Figure 109 shows some of the castings which are made with this mould.

[Fig. 109 Terminal mould and castings made in it]

Figure 109 shows a Terminal Mould which casts five reversible end terminal connectors, a cable connector, such as is used on the Maxwell battery, and two washers often needed in making a tight connection.

[Fig. 110 Screw mould]

Figure 110 shows a Screw Mould which casts standard square lead leads on four screws in one operation, two 5/8 inch and two 3/8 inch. This mould has a screw adjustment in the base which makes each cavity adaptable to any length screw.

EQUIPMENT FOR WORK ON CASES

The acid proof asphaltum paint, paint brushes, wood chisels, wood plane, and earthenware jars are all standard articles.

[Fig. 111 Battery turntable]

Figure 111 shows a battery turntable which is very convenient when painting cases, lead burning, etc.

TOOLS FOR GENERAL WORK

Most of the articles in this list require no explanation. Some of them, however, are of special construction.

Separator Cutter. Some battery supply houses sell special separator cutters, but a large size photograph trimmer is entirely satisfactory.

[Fig. 112]

Fig. 112. Plate Press for Pressing Swollen, Bulged Negatives (After Plates Have Been Fully Charged)

[Fig. 113]

Fig. 113. Inserting Plate Press Boards Between Negatives Preparatory to Pressing

Plate Press. Figure 112 shows a special plate press in which the plates are pressed between wooden jaws. No iron can come into contact with the plates. This is a very important feature, since iron in solution causes a battery to lose its charge very quickly. This press is made of heavy hardwood timbers, and may be set on a bench or mounted on the wall. A set of lead coated troughs carry away the acid which is squeezed from the plates.

[Fig. 114 Showing how negatives should be placed in the plate press]

This press is designed for pressing negative plates, the active material of which has become bulged or swollen. A plate in this condition has a low capacity and cannot give good service. Swollen negatives often make it impossible to replace the plates in a jar. When negatives are found to be bulged or swollen, the battery must be fully charged, and the negatives then pressed. To do this, plate press boards, which are of acid proof material, and of the proper thickness are inserted between the negatives, as shown in Figure 113, and the plates are then set in the press is shown in Figure 114.

[Fig. 115 Negative group before and after pressing]

Figure 115 shows a group before and after pressing. Note that pressing has forced the active material back into the grid where it must be if the plates are to give good service. Never send out a battery with swollen or bulged negatives.

Slightly buckled negatives may also be straightened out in the Plate Press. Positives do not swell or bulge as they discharge, but shed the active material. They are therefore not pressed Positives buckle, of course, but should never be pressed to straighten them. The lead peroxide of the positive plates is not elastic like the spongy the negatives, and if positives are pressed to straighten them the paste will crack and break from the grid. Slightly buckled positives may be used, but if they are so badly buckled that it is impossible to reassemble the element or put the element back into the jars, they should be discarded.

[Fig. 116 Battery carrier]

[Fig. 117 Battery truck]

Battery Carrier. Figure 116 shows a very convenient battery carrier, having a wooden handle with two swinging steel hooks for attaching to the battery to be carried. With this type of carrier no strain is put on the handle, as is the case if a strap is used.

Battery Truck. When a battery must be moved any considerable distance, a truck, such as that shown in Figure 117 should be used. This truck may easily be made in the shop, or may be made at a reasonable cost in a carpenter shop. The rollers should be four inches or more in diameter and should preferably be of the ball-bearing type. Rubber tires on the rollers are a great advantage, since the rubber protects the rollers from acid and also eliminates the very disagreeable noise which iron wheels make, especially in going over a concrete floor or sidewalk. The repairman need not make his truck exactly like that shown in Figure 117, which is merely shown to give a general idea of how such a truck should be constructed.

The truck shown in Figure 117 was made from a heavy wooden box. With this construction lifting batteries is largely eliminated, which is most desirable, since a battery is not the lightest thing in the world. The battery is carried in a horizontal position and the truck is small enough to be wheeled between cars in the shop.

[Fig. 118 Another battery truck]

Another form of battery truck is shown in Figure 118, although this, is not as good as that shown in Figure 117.

CADMIUM TEST SET AND HOW TO MAKE THE TEST

As the cell voltage falls while the battery is on discharge, the voltage of the positive plates, and also the voltage of the negative plates falls. When the battery is charged again the voltages of both positive and negative plates rise. If a battery gives its rated ampere-hour capacity on discharge, we do not care particularly how the voltages of the individual positive and negative groups change. If, however, the battery fails to give its rated capacity, the fault may be due to defective positives or defective negatives.

If the voltage of a battery fails to come up when the battery is put on charge, the trouble may be due to either the positives or negatives. Positives and negatives may not charge at the same rate, and one group may become fully charged before the other group. This may be the case in a cell which has had a new positive group put in with the old negatives. Cadmium tests made while the battery is on charge will tell how fully the individual groups are charged.

Since the voltages of the positives and negatives both fall as a battery is discharged, and rise as the battery is charged, if we measure the voltages of the positives and negatives separately, we can tell how far each group is charged or discharged. If the voltage of each cell of a battery drops to 1.7 before the battery has given its rated capacity, we can tell which set of plates has become discharged by measuring the voltages of positives and negatives separately. If the voltage of the positives show that they are discharged, then the Positives are not up to capacity. Similarly, negatives are not up to capacity if their voltage indicates that they are discharged before the battery has given its rated capacity.

Cadmium readings alone do not give any indication of the capacity of a battery, and the repairman must be careful in drawing conclusions from Cadmium tests.

In general it is not always safe to depend upon Cadmium tests on a battery which has not been opened, unless the battery is almost new. Plates having very little active material, due to shedding, or due to the active material being loosened from the grid, will often give good Cadmium readings, and yet a battery with such plates will have very little capacity. Such a condition would be disclosed by an actual examination of the plates, or by a capacity discharge test.

How Cadmium Tests Are Made

To measure the voltages of the positives and negatives separately, Cadmium is used. The Cadmium is dipped in the electrolyte, and a voltage reading is taken between the Cadmium and the plates which are to be tested. Thus, if we wish to test the negatives, we take a voltage reading between the Cadmium and the negatives, as shown in Fig. 119. Similarly, if we wish to test the positives, we take a voltage reading between the Cadmium and the positives, as shown in Fig 120.

[Fig. 119 Making cadmium test on negative plates]

[Fig. 120 Making cadmium test on positive plates]

In dipping the Cadmium into the electrolyte, we make two cells out of the battery cell. One of these consists of the Cadmium and the positives, while the other consists of the Cadmium and the negatives. If the battery is charged, the Cadmium forms the negative element in the Cadmium-Positives cell, and is the positive element in the Cadmium-Negatives cell. The voltage of the Cadmium does not change, and variations in the voltage readings obtained in making Cadmium tests are due to changes in the state of charge of the negative and positive plates which are being tested.

What Cadmium Is: Cadmium is a metal, just like iron, copper, or lead. It is one of the chemical elements; that is, it is a separate and distinct substance. It is not made by mixing two or more substances, as for instance, solder is made by mixing tin and lead, but is obtained by separating the cadmium from the compounds in which it is found in nature, just as iron is obtained by treatment of iron ore in the steel mill.

When Cadmium Readings Should Be Made

1. When the battery voltage drops to 1.7 per cell on discharge before the battery has delivered its rated ampere-hour capacity, at the 5-hour rate when a discharge test is made.

2. When a battery on charge will not "come up," that is, if its voltage will not come up to 2.5-2.7 per cell on charge, and its specific gravity will not come up to 1.280-1.300.

3. Whenever you charge a battery, at the end of the charge, when the voltage and specific gravity no longer rise, make Cadmium tests to be sure that both positives and negatives are fully charged.

4. When you put in a new group, charge the battery fully and make Cadmium tests to be sure that both the new and old groups are fully charged.

5. When a 20-minute high rate discharge test is made. See page 267.

That Cadmium Readings should be taken only while a battery is in action; that is, while it is on discharge, or while it is on charge.

Cadmium Readings taken on a battery which is on open circuit are not reliable.

When you are not using the Cadmium, it should be put in a vessel of water and kept there. Never let the Cadmium become dry, as it will then give unreliable readings.

Open Circuit Voltage Readings Worthless

Voltage readings of a battery taken while the battery is on open circuit; that is, when no current is passing through the battery, are not reliable. The voltage of a normal, fully charged cell on open circuit is slightly over 2 volts. If this cell is given a full normal discharge, so that the specific gravity of its electrolyte drops to 1.150, and is allowed to stand for several hours after the end of the discharge, the open circuit voltage will still be 2 volts. Open circuit voltage readings are therefore of little or no value, except when a cell is "dead," as a dead cell will give an open circuit voltage very much less than 2, and it may even give no voltage at all.

What the Cadmium Test Set Consists of

The Cadmium Tester consists of a voltmeter, Fig. 121, and two pointed brass prods which are fastened in wooden handles, as shown in Fig. 122. A length of flexible wire having a terminal at one end is soldered to each prod for attachment to the voltmeter. Fastened at right angles to one of the brass prods is a rod of pure cadmium.

[Fig. 121 Special cadmium test voltmeter, & Fig. 122 Cadmium test leads]

Cadmium tests may be made with any accurate voltmeter which gives readings up to 2.5 volts in divisions of .05 volt.

The instructions given below apply especially to the special AMBU voltmeter but these instructions may also be used in making cadmium tests with any voltmeter that will give the correct reading.

The AMBU Cadmium Voltmeter

Fig. 121 is a view of the special AMBU Voltmeter, which is designed to be used specially in making Cadmium tests. Fig. 122 shows the Cadmium leads. The four red lines marked "Neg. Charged," "Neg. Discharged," "Pos. Charged," and "Pos. Discharged," indicate the readings that should be obtained. Thus, in testing the positives of a battery on charge, the pointer will move to the line which is marked "Pos. Charged," if the positive plates are fully charged. In testing the negatives, the pointer will move to the line marked "Neg. Charged," which is to the left of the "0" line, if the negatives are fully charged, and so on. Figs. 123, 124, 125 and 126 show the pointer in the four positions on the scale which it takes when testing fully charged or discharged plates. In each figure the pointer is over one of the red lines on the scale. These figures also show the readings, in volts, obtained in making the cadmium tests on fully charged or completely discharged plates.

[Fig. 123 Voltmeter showing reading obtained when testing charged negative; & Fig. 124 Showing reading obtained when testing charged positives]

[Fig. 125 Voltmeter showing reading obtained when testing discharged negatives; and Fig. 126 Showing reading obtained when testing discharged positives]

If Pointer Is Not Over the "0" Line: It sometimes happens, in shipping the instrument, and also in the use of it, that the pointer does not stand over the "0" line, but is a short distance away. Should you find this to be the case, take a small screwdriver and turn the screw which projects through the case, and which is marked "Correct Zero," so as to bring the pointer exactly over the "0" line on the scale while the meter has no wires connected to its binding posts.

Connections of Cadmium Leads: In making Cadmium Tests, connect the prod which has the cadmium fastened to it to the negative voltmeter binding post. Connect the plain brass prod to the positive voltmeter binding post. The connections to the AMBU Cadmium Voltmeter are shown in Fig. 127.

Testing a Battery on Discharge

The battery should be discharging continuously, at a constant, fixed rate, see page 265.

[Fig. 127 AMBU Cadmium Voltmeter]

Generally, on a starting ability test (see page 267), the positive Cadmium readings will start at about 2.05 volts for a hard or very new set of positives, and at 2.12 volts or even higher for a set of soft or somewhat developed positives, and will drop during the test, ending at 1.95 volts or less. The negative Cadmium readings will start at 0.23 volt or higher, up to 0.30, and will rise gradually, more suddenly toward the end if the plates are old, ending anywhere above 0.35 and up to 0.6 to 0.7 for poor negatives.

Short Circuited Cells: In cases of short circuited cells, the voltage of the cell will be almost down to zero. The Cadmium readings would therefore be nearly zero also for both positives and negatives. Such a battery should be opened for inspection and repairs.

Testing a Battery on Charge

The Battery should be charging at the finishing rate. (This i's usually stamped on the battery box.) Dip the cadmium in the electrolyte as before, and test the negatives by holding the plain prod on the negative post of the cell. See Fig. 119. Test the positives in a similar manner. See Fig. 120. The cell voltage should also be measured. If the positives are fully charged, the positive cadmium reading will be such that the pointer will move to the red line marked "Pos. Charged." See Fig. 125. If you are using an ordinary voltmeter, the meter will give a reading of from 2.35 to 2.42 volts. The negatives are then tested in a similar manner. The negative-cadmium reading on an ordinary voltmeter will be from .175 to .2 to the left of the "0" line; that is, the reading is a reversed one. If you are using the special ABM voltmeter, the pointer will move to the red line marked "Neg. Charged." See Fig. 123. The cell voltage should be the sum of the positive-cadmium and the negative cadmium readings.

If the voltage of each cell will not come up to 2.5 to 2.7 volts on charge, or if the specific gravity will not rise to 1.280 or over, make the cadmium tests to determine whether both sets of plates, or one of them, give readings indicating that they are fully charged. If the positives will not give a reading of at least 2.35 volts, or if the negatives will not give a reversed reading of at least 0.1 volt, these plates lack capacity.

In case of a battery on charge, if the negatives do not give a minus Cadmium reading, they may be lacking in capacity, but, on the other hand, a minus negative Cadmium reading does not prove that the negatives are up to hill capacity. A starting ability discharge test (page 267) is the only means of telling whether a battery is up to capacity.

Improperly treated separators will cause poor negative-Cadmium readings to be obtained. The charging rate should be high enough to give cell voltages of 2.5-2.7 when testing negatives. Otherwise it may not be possible to get satisfactory negative-Cadmium reading. Separators which have been allowed to become partly dry at any time will also make it difficult to obtain satisfactory negative-Cadmium readings.

HIGH RATE DISCHARGE TESTERS

(See page 265 for directions for making tests.)

Figure 128 shows a high rate discharge cell tester. It consists of a handle carrying two heavy prongs which are bridged by a length of heavy nichrome wire. When the ends of the prongs are pressed down on the terminals of a cell, a current of 150 to 200 amperes is drawn from the cell. A voltage reading of the cell, taken while this discharge current is flowing is a means of determining the condition of the cell, since the heavy discharge current duplicates the heavy current drawn by the starting motor. Each prong carries a binding post, a low reading voltmeter being connected to these posts while the test is made. This form of discharge tester is riot suitable for making starting ability discharge tests, which are described on page 267.

Other forms of high rate discharge testers are made, but for the shop the type shown in Figure 128 is most convenient, since it is light and portable and has no moving parts, and because the test is made very quickly without making any connections to the battery. Furthermore, each cell is tested separately and thus six or twelve volt batteries may be tested without making any change in the tester.

For making starting ability discharge tests at high rates, a carbon plate or similar rheostat is most suitable, and such rheostats are on the market.

[Fig. 128 High rate discharge tester]

[Fig. 129 Paraffine dip pot]

PARAFFINE DIP POT

Paper tags are not acid proof, and if acid is spilled on tags tied to batteries which are being repaired, the writing on the tags is often obliterated so that it is practically impossible to identify the batteries. An excellent plan to overcome this trouble is to dip the tags in hot paraffine after they have been properly filled out. The writing on the tags can be read easily and since paraffine is acid proof, any acid which may be spilled on the paraffine coated tags will not damage the tags in any way.

Figure 129 shows a paraffine dip pot. A small earthenware jar is best for this purpose. Melt the paraffine slowly on a stove, pour it into the pot, and partly immerse a 60-watt carbon lamp in the paraffine as shown. The lamp will give enough heat to keep the paraffine melted, without causing it to smoke to any extent. After filling out a Battery Card, dip it into the Paraffine, and hold the card above the pot to let the excess paraffine run off. Let the paraffine dry before attaching the tag to the battery, otherwise the paraffine may be scratched off.

WOODEN BOXES FOR BATTERY PARTS

[Fig. 130]

Fig. 130. Boxes for Holding Parts of Batteries Being Prepared

Figure 130 shows a number of wooden boxes, about 12 inches long, 8 inches wide, and 4 inches deep. These boxes are very useful for holding the terminals inter-cell connectors, covers, plugs, etc., of batteries which are dismantled for repairs. Write the name of the owner with chalk on the end of the box, and rub the name off after the battery has been put together again. The boxes shown in Figure 130 had been used for plug tobacco, and served the purpose very well. The larger box shown in Figure 130 may be used for collecting old terminals, inter-cell connectors, lead drillings, etc.

EARTHENWARE JARS

The twenty gallon size is very convenient for waste acid, old separators, and any junk parts which are wet with acid. The jars are acid proof and will help keep the shop floor dry and anything which will help in this is most desirable.

ACID CARBOYS

Acid is shipped in large glass bottles around each of which a wooden box is built to prevent breakage, the combination being called a "carboy." Since the acid is heavy, some means of drawing it out of the bottle is necessary. One method is illustrated in Figure 131, wooden rockers being screwed to the box in which the bottle is placed.

[Fig. 131 A simple method of drawing acid from a carboy]

A very good addition to the rockers shown in Figure 131 is the inner tube shown in Figure 132. In this illustration the rockers are not shown, but should be used. The combination of the rockers with the inner tube gives a very convenient method of pouring acid from a carboy, since the heavy bottle need not be lifted, and since it helps keep the floor and the top of the box dry.

[Fig. 132 Use of inner tube to protect box when pouring acid]

The rubber tube shown in Figure 132 is a piece of 4 inch inner tube which is slit down one side to make it lie flat. Near one end is cut a hole large enough to fit tightly over the neck of the acid bottle. Slip this rubber over the neck of the bottle and allow the long end to hang a few inches over the side of the carboy bottle or box. This is for pouring acid from a carboy when it is too full to allow the contents to be removed without spilling. This device will allow the contents of the carboy to be poured into a crock or other receptacle placed on the floor without spilling, and also prevents dirt that may be laying on top of the carboy from falling into the crock.

[Fig. 133 Siphon for drawing acid from carboy]

Figure 133 shows a siphon method for drawing acid from a bottle, although this method is more suitable for distilled water than for acid. "A" is the bottle, "B" a rubber stopper, "C" and "D" are 3/8 inch glass or hard rubber tubes, "E" is a length of rubber tubing having a pinch clamp at its lower end. To use this device, the stopper and tubes are inserted in the bottle, and air blown or pumped in at "C," while the pinch clamp is open, until acid or water begins to run out of the lower end of tubing "E." The pinch clamp is then released. Whenever acid or water is to be drawn from the bottle the pinch clamp is squeezed so as to release the pressure on the tube. The water or acid will flow down the tube automatically as long as the pinch clamp is held open. The clamp may be made of flat or round spring brass or bronze. This is bent round at (a). At (c) an opening is made, through which the part (b) is bent. The clamp is operated by pressing at (d) and (e). The rubber tubing is passed through the opening between (b) and (c).

This method is a very good one for the small bottle of distilled water placed on the charging bench to bring the electrolyte up to the proper height. The lower end of tube (e) is held over the vent hole of the cell. The pinch clamp is then squeezed and water will flow. Releasing the clamp stops the flow of water instantly. If tube (e) is made long enough, the water bottle may be set on the elevated shelf extending down the center of the charging bench.

[Fig. 134 Foot pump for drawing acid from carboy]

Figure 134 shows another arrangement, using a tire pump. D and E are 3/8 inch hard rubber tubes. D is open at both ends and has a "T" branch to which the pump tubing is attached. To operate, a finger is held over the upper end of D, and air is pumped into the acid bottle, forcing the acid into the vessel F. To stop the flow of acid, the finger is removed from D. This stops the flow instantly. This method is the most satisfactory one when fairly large quantities of acid or water are to be drawn off.

SHOP LAYOUTS

The degree of success which the battery repairman attains depends to a considerable extent upon the workshop in which the batteries are handled. It is, of course, desirable to be able to build your shop, and thus be able to have everything arranged as you wish. If you must work in a rented shop, select a place which has plenty of light and ventilation. The ventilation is especially important on account of the acid fumes from the batteries. A shop which receives most of its light from the north is the best, as the light is then more uniform during the day, and the direct rays of the sun are avoided. Fig. 38 shows a light, well ventilated workroom.

The floor should be in good condition, since acid rots the wood and if the floor is already in a poor condition, the acid will soon eat through it. A tile floor, as described below, is best. A wooden floor should be thoroughly scrubbed, using water to which baking soda has been added. Then give the floor a coat of asphaltum paint, which should be applied hot so as to flow into all cracks in the wood. When the first coat is dry, several more coats should be given. Whenever you make a solution of soda for any purpose, do not throw it away when you are through with it. Instead, pour it on the floor where the acid is most likely to be spilled. This will neutralize the acid and prevent it from rotting the wood.

If you can afford to build a shop, make it of brick, with a floor of vitrified brick, or of tile which is not less than two inches thick, and is preferably eight inches square. The seams should not be less than one-eighth inch wide, and not wider than one fourth. They should be grouted with asphaltum, melted as hot and as thin as possible (not less than 350 deg. F.). This should be poured in the seams. The brick or tile should be heated near the seams before pouring in the asphaltum. When all the seams have been filled, heat them again. After the second heating, the asphaltum may shrink, and it may be necessary to pour in more asphaltum.

If possible, the floor should slope evenly from one end of the room to the other. A lead drainage trough and pipe at the lower end of the shop will carry off the acid and electrolyte.

It is a good plan to give all work benches and storage racks and shelves at least two coatings of asphaltum paint. This will prevent rotting by the acid.

The floor of a battery repair shop is, at best, a wet, sloppy affair, and if a lead drainage trough is too expensive, there should be a drain in the center of the floor if the shop is small, and several if the shop is a large one. The floor should slope toward the drains, and the drain-pipes should be made of glazed tile.

To keep the feet as dry as possible, rubbers, or even low rubber boots should be worn. Sulphuric acid ruins leather shoes, although leather shoes can be protected to a certain extent by dipping them in hot paraffine.

[Fig. 135 Wooden grating on shop floor to give dry walking surface for the repairman]

A good plan is to lay a wooden grating over the floor as shown in Figure 135. Water and acid will run down between the wooden strips, leaving the walking surface fairly dry. If such a grating is made, it should be built in sections which may be lifted easily to be washed, and to permit washing the floor. Keep both the grating and the floor beneath covered with asphaltum paint to prevent rotting by acid. Once a week, or oftener, if necessary, sweep up all loose dirt and then turn the hose on the floor and grating to wash off as much acid as possible. When the wood has dried, a good thing to do is to pour on the floor and grating several pails of water in which washing soda or ammonia has been dissolved.

Watch your floor. It will pay-in better work by yourself and by the men working for you. Have large earthenware jars set wherever necessary in which lead drillings, old plates, old connectors, old separators, etc., may be thrown. Do not let junk cases, jars, separators, etc., accumulate. Throw them away immediately and keep your shop clean. A clean shop pleases Your customers, —and satisfied customers mean success.

On the following pages a number of shop layouts are given for both large and small shops. The beginner, of course, may not be able to rent even a small shop, but he may rent part of an established repair shop, and later rent an entire shop. A man working in a corner of an established service must arrange his equipment according to the space available. Later on, when he branches out for himself, he should plan his shop to got the best working arrangement. Figure 136 shows a suggested layout for a small shop. Such a layout may have to be altered because of the size and shape of the shop, and the location of the windows.

[Fig. 136 Floorplan: layout for a small shop]

As soon as growth of business permits, a shop should have a drive-in, so that the customer may bring his car off the street. Without a drive-in all testing to determine what work is necessary will have to be done at the curb, which is too public for many car owners. A drive-in is also convenient if a customer leaves his car while his battery is being repaired. To a certain extent, the advantages of a drive-in may be secured by having a vacant lot next to the shop, with a covering of cinders. As soon as possible, however, a shop which is large enough to have a drive-in should be rented or built.

Figure 137 shows a 24 x 60 shop with space for three cars. The shop equipment is explained in the table.

Figure 138 shows a 40 x 75 shop with room for six cars and a drive-in and drive-out. This facilitates the handling of the cars.

Figure 139 shows a 30 x 100 shop in a long and somewhat narrow building. It also has a drive-in and drive-out.

Another arrangement for the same sized shop as shown in the preceding illustration is shown in Figure 140. Here the drive-out is at the side and this layout is, therefore, suitable for a building located on a corner, or next to an alley.

Figure 141 shows a larger shop, which may be used after the business has grown considerably.

Figure 142 shows a layout suitable for the largest station.

Somewhere between Figures 136 and 142 is a layout for any service station. The thing to do is to select the one most suitable for the size of the business, and to fit local conditions, If a special building is put up, local conditions are not so important.

If a shop is rented, it may not be possible to follow any of the layouts shown in Figs. 136 to 142. However, the layout which is best adapted for the actual shop should be selected as a guide, and the equipment shown obtained. This should then be arranged as nearly like the pattern layout as the shop arrangement will permit.

Concerning Light

Light is essential to good work, so you must have plenty of good light and at the right place. For a light that is needed from one end of a bench to the other, to look into each individual battery, or to take the reading of each individual battery, there is nothing better than a 60 Watt tungsten lamp under a good metal shade, dark on outside and white on inside.

A unique way to hang a light and have it movable from one end of the bench to the other, is to stretch a wire from one end of the bench to the other. Steel or copper about 10 or 12 B & S gauge may be used. Stretch it about four or five feet above top of bench directly above where the light is most needed. If You have a double charging bench, stretch the wire directly above middle of bench. Before fastening wire to support, slip an old fashioned porcelain knob (or an ordinary thread spool) on the wire. The drop cord is to be tied to this knob or spool at whatever height you wish the light to hang (a few inches lower than your head is the right height).

Put the ceiling rosette above center of bench; cut your drop cord long enough so that you can slide the light from one end of bench to the other after being attached to rosette. Put vaseline on the wire so the fumes of gas will not corrode it. This will also make the spool slide easily. This gives you a movable, flexible light, with which you will reach any battery on bench for inspection. The work bench light can be rigged up the same way and a 75 or 100 Watt nitrogen lamp used.

[Fig. 137 Shop layout]

[Fig. 138 Shop layout]

Fig. 137 and 138: A-Receiving Rack. B-Portable Electric Drill, or Hand Drill. C-Wash Tank, D-Tear Down Bench. E-Hot Water Pan. F-Waiting Rack (5 Shelves). G-Repair Bench (6 ft. by 2 ft. 3 in.). H-Charging Table (3 Circuits). I-Electrolyte(10 Gal. Crocks). J-Separator Rack. K-Generator. L-Switchboard. M-Stock Bins, N-New Batteries, O-Live storage. P-Sealing Compound. R-Ready Rack (5-Shelves). S-Dry Storage. (S is not in Fig. 137.)

[Fig. 139, 140 & 141 Various shop layouts]

Fig. 139, 140 and 141: A-Receiving Rack. B-Power Drill. C-Wash Tank. D-Tear Down Bench. E-Hot Water Pan. F-Waiting Rack (6 Shelves). G-Repair Bench. H-Charging Table (3 Circuits). I-Electrolyte (10 Gal. Crocks). J-Separator Rack. K-Generator. L-Switchboard. M-Stock Bins. N-New Batteries. O-Live storage. P-Sealing Compound. R-Ready Rack (5-Shelves). S-Dry Storage. T-Torn Down Parts. (O and T in 141, not in 139 and 140.)

[Fig. 142 Shop layout]

Fig. 142: A-Receiving Rack. B-Power Drill. C-Wash Tank. D-Tear Down Bench. E-Hot Water Pan. F-Waiting Rack (6 Shelves). G-Repair Bench. H-Charging Table. I-Electrolyte (10 Gal. Crocks). J-Separator Rack. K-Generator. L-Switchboard. M-Stock Bins. N-New Batteries. O-Live storage. P-Sealing Compound. R-Ready Rack. S-Dry Storage. T-Torn Down Parts.

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CHAPTER 12. GENERAL SHOP INSTRUCTIONS. —————————————

CHARGING BATTERIES.

The equipment for charging batteries, instructions for building and wiring charging benches have already been given. What we shall now discuss is the actual charging. The charge a battery receives on the charging bench is called a "bench charge."

Battery charging in the service station may be divided into two general classes:

1. Charging batteries which have run down, but which are otherwise in good condition, and which do not require repairs.

2. Charging batteries during or after the repair process.

The second class of charging is really a part of the repair process and will-be described in the chapter on "Rebuilding the Battery." Charging a battery always consists of sending a direct current through it, the current entering the battery at the positive terminal and leaving it at the negative terminal, the charging current, of course, passing through the battery in the opposite direction to the current which the battery produces when discharging. When a battery discharges chemical changes take place by means of which electrical energy is produced. When a battery is on charge, the charging current causes chemical changes which are the reverse of those which take place on discharge and which put the active materials and electrolyte in such a condition that the battery serves as a source of electricity when replaced in the car.

Batteries are charged not only in a repair shop but also in garages which board automobiles, and in car dealers' shops. No matter where a battery is charged, however, the same steps must be taken and the same precautions observed.

When a Bench Charge is Necessary:

(a) When a battery runs down on account of the generator on the car not having a sufficient output, or on account of considerable night driving being done, or on account of frequent use of the starting motor, or on account of neglect on the part of the car owner.

(b) Batteries used on cars or trucks without a generator, or batteries used for Radio work should, of course, be given a bench charge at regular intervals.

(c) When the specific gravity readings of all cells are below 1.200, and these readings are within 50 points of each other.

Should the gravity reading of any cell be 50 points lower or higher than that of the other cells, it is best to make a 15-seconds high rate discharge test (see page 266) to determine whether the cell is defective or whether electrolyte has been lost due to flooding caused by over-filling and has been replaced by water or higher gravity electrolyte. If any defect shows up during the high rate test, the battery should be opened for inspection. If no defect shows up, put the battery on charge.

(d) When the lamps burn dimly while the engine is running.

(e) When the lamps become very dim when the starting switch is closed.

If a battery is tested by turning on the lights and then closing the starting switch, make sure that there is no short-circuit or ground in the starting motor circuits. Such trouble will cause a very heavy current to be drawn from the battery, resulting in a drop in the voltage of the battery.

(f) When the voltage of the battery has fallen below 1.7 volts per cell, measured while all the lights are turned on.

(g) When the owner has neglected to add water to the cells regularly, and the electrolyte has fallen below the tops of the plates.

(h) When a battery has been doped by the addition of electrolyte or acid instead of water, or when one of the "dope" electrolytes which are advertised to make old, worn out batteries charge up in a ridiculously short time and show as much life and power as a new battery. Use nothing but a mixture of distilled water and sulphuric acid for electrolyte. The "dope" solutions are not only worthless, but they damage a battery considerably and shorten its life. Such a "doped" battery may give high gravity *readings and yet the lamps will become very dim when the starting motor cranks the car, the voltage per cell will be low when the lights are burning, or low voltage readings (1.50 per cell) will be obtained if a high rate discharge test is made.

Every battery which comes in for any reason whatsoever, or any battery which is given a bench charge whenever necessary should also be examined for other defects, such as poorly burned on connectors and terminals, rotted case, handles pulled off, sealing compound cracked, or a poor sealing job between the covers and jars, or covers and posts. A slight leakage of electrolyte through cracks or imperfect joints between the covers and jars or covers and posts is very often present without causing any considerable trouble. If any of the other troubles are found, however, the battery needs repairing.

Arrangement of Batteries on Charging Bench. If a battery comes in covered with dirt, set it on the wash rack or in the sink and clean it thoroughly before putting it on charge. In setting the batteries on the charging bench, place all of them so that the positive terminal is toward the right as you face the bench. The positive terminal may be found to be painted red, or may be stamped "+", "P", or "POS". If the markings on one of the terminals has been scratched or worn off, examine the other terminal. The negative terminal may be found to be painted black, or be stamped "-", "N" or "NEG".

If neither terminal is marked, the polarity may be determined with a voltmeter, or by a cadmium test. To make the voltmeter test, hold the meter wires on the battery terminals, or the terminals of either end cell. When the voltmeter pointer moves to the right of the "0" line on the scale, the wire attached to the "" terminal of the meter is touching the positive battery terminal, and the wire attached to the "-" terminal of the meter is touching the negative battery terminal. If this test is made with a meter having the "0" line at the center of the scale, be sure that you know whether the pointer should move to the left or right of the "0" line when the wire attached to the "" meter terminal is touching the positive battery terminal.

Another method of determining which is the positive terminal of the battery is to use the cadmium test. When a reading of about two volts is obtained, the prod held on one of the cell terminals is touching the positive terminal. When a reading of almost zero is obtained, that is, when the needle of the meter just barely moves from the "0" line, or when it does not move at all, the prod held on one of the cell terminals is touching the negative terminal. This test, made while the battery is on open-circuit, is not a regular cadmium test, but is made merely to determine the polarity of the battery.

The polarity of the charging line will always be known if the bench is wired permanently. The positive charging wire should always be to the right. If a separate switch is used for each battery (Figures 43 and 65), the wire attached to the right side of the switch is positive. If the batteries are connected together by means of jumpers (Figures 44 and 47), the positive charging wire should be at the right hand end of the bench as seen when facing the bench. If a constant-potential charging circuit is used as shown in Figure 48, the positive bus-bar should be at the top and the neutral in the center, and the negative at the bottom.

If the polarity of the charging line wires is not known, it may be determined by a voltmeter, in the same way as the batter-, polarity is determined. If this is done, care should be taken to use a meter having a range sufficient to measure the line voltage. If no such voltmeter is available, a simple test is to fill a tumbler with weak electrolyte or salt water and insert two wires attached to the line. The ends of these wires should, of course, be bare for an inch or more. Hold these wires about an inch apart, with the line alive. Numerous fine bubbles of gas will collect around the negative wire.

With the polarities of all the batteries known, arrange them so that all the positive terminals are at the right. Then connect them to the individual switches (see Figure 43), or connect them together with jumpers (see Figure 44), being sure to connect the negative of one battery to the positive of the next. Connect the positive charging line wire to the positive terminal of the first battery, and the negative line wire to the negative terminal of the last battery. See page 105.

With all connections made, and before starting to charge, go over all the batteries again very carefully. You cannot be too careful in checking the connections, for if one or more batteries are connected reversed, they will be charged in the wrong direction, and will most likely be severely damaged.

As a final check on the connections of the batteries on the line, measure the total voltage of these batteries and see if the reading is equal to two times the total number of cells on the line.

Now inspect the electrolyte in each cell. If it is low, add distilled water to bring the electrolyte one-half inch above the plates. Do not wait until a battery is charged before adding water. Do it now. Do not add so much water that the electrolyte comes above the lower end of the vent tube. This will cause flooding.

Charging, Rate. If you connect batteries of various sizes together on one circuit, charge at the rate which is normal for the smallest battery. If the rate used is the normal one for the larger batteries, the smaller batteries will be overheated and "boiled" to death, or they may gas so violently as to blow a considerable portion of the active material from the plates.

It is quite possible to charge 6 and 12 volt batteries in series. The important point is not to have the total number of cells too high. For instance, if the 10 battery Tungar is used, ten 6-volt batteries (30 cells), or any combination which gives 30 cells or less may be used. For instance, five 12-volt batteries (30 cells), or six 6-volt batteries (18 cells) and two 12-volt batteries (12 cells), or any other combination totaling 30 cells may be used. The same holds true for motor-generators.

The charging rate is generally determined by the size of the charging outfit. The ten battery Tungar should never have its output raised above 6 amperes. A charging rate of 6 amperes is suitable for all but the very smallest batteries. In any case, whether you are certain just what charging rate to use, or not, there are two things which will guide you, temperature and gassing.

1. Temperature. Have a battery thermometer (Figure 37) on hand, and measure the temperature of the electrolyte of each cell on the line. If you note that some particular cell is running hotter than the others, keep the thermometer in that cell and watch the temperature. Do not let the temperature rise above 110 degrees Fahrenheit, except for a very short time. Should the highest of the temperature of the cells rise above 110 degrees, reduce the charging rate.

2. Gassing. Near the end of a charge and when the specific gravity has stopped rising, or is rising very slowly, bubbles of gas will rise from the electrolyte, this being due to the charging current decomposing the water of the electrolyte into hydrogen and oxygen. If this gassing is too violent, a considerable amount of active material will be blown from the plates. Therefore, when this gassing begins, the charging rate should be reduced, unless the entire charging has been done at a low rate, say about five amperes.

If gassing begins in any cell soon after the charge is started, or before the specific gravity has reached its highest point, reduce the charging rate to eliminate the gassing.

If one battery or one cell shows a high temperature and the others do not, or begins gassing long before the others do, remove that battery from the charging line for further investigation and replace it with another so as not to slow up the charge of the other batteries which are acting normally.

As long as excessive temperatures and too-early gassing are avoided, practically any charging rate may be used, especially at the start. With a constant potential charging set, as shown in Figure 48, the charge may start at as high a rate as 50 amperes. If this system of charging is used, the temperature must be watched very carefully and gassing must be looked for. With the usual series method of charging, a charge may, in an emergency, be started at 20 amperes or more. As a general rule do not use a higher rate than 10 amperes. A five ampere rate is even better, but more time will be required for the charge.

Time Required for a Charge. The time required is not determined by the clock, but by the battery. Continue the charge until each cell is gassing freely (not violently) and for five hours after the specific gravity has stopped rising. The average condition of batteries brought in for charge permits them to be fully charged in about 48 hours, the time being determined as stated above. Some batteries may charge fully in less time, and some may require from four days to a week, depending entirely upon the condition of the batteries. Do not give any promise as to when a recharge battery will be ready. No one can tell how long it will take to charge.

Specific Gravity at the End of the Charge. The specific gravity of the electrolyte in a fully charged cell should be from 1.280 to 1.300. If it varies more than 10 points above or below these values, adjust it by drawing off some of the electrolyte with a hydrometer and adding water to lower the gravity, or 1.400 acid to raise the gravity. After adjusting the gravity charge for one hour more.

Battery Voltage at End of Charge. The voltage of a fully charged cell is from 2.5 to 2.7 when the temperature of the electrolyte is 80 degrees Fahrenheit; 2.4 to 2.6 when the temperature of the electrolyte is 100 degrees Fahrenheit, and 2.35 to 2.55 volts when the temperature of the electrolyte is 120 degrees Fahrenheit, and this voltage, together with hydrometer readings of 1.280-1.300 indicate that the battery is fully charged.

Just before putting a battery which has been charged into service, give it a 15 seconds high rate discharge test, see page 266.

Painting. Before returning a battery to the owner wipe it perfectly clean and dry. Then wipe the covers, terminals, connectors and handles with a rag wet with ammonia. Next give the case a light coat of black paint which may be made by mixing lamp black and shellac. This paint dries in about five minutes and gives a good gloss. The customer may not believe that you are returning the battery which he brought in but he will most certainly be pleased with your service and will feel that if you take such pains with the outside of his battery you will certainly treat the inside with the same care when repairs are necessary. The light coat of paint costs very little for one battery, but may bring you many dollars worth of work.

Level of Electrolyte. During charge the electrolyte will expand, and will generally flow out on the covers. This need not be wiped off until the end of the charge. When the electrolyte has cooled after the battery is taken off charge, it must be about 1/2 inch above the plates. While the electrolyte is still warm it will stand higher than this, but it should not be lowered by drawing off some of it, as this will probably cause it to be below the tops of the plates and separators when it cools.

TROUBLES

If all goes well, the charging process will take place as described in the preceding paragraphs. It frequently happens, however, that all does not go well, and troubles arise. Such troubles generally consist of the following:

Specific gravity will not rise to 1.280. This may be due to the plates not taking a full charge, or to water having been used to replace electrolyte which has been spilled. To determine which of these conditions exist, make cadmium test (see page 174) on the positives and negatives, also measure the voltage of each cell. If these tests indicate that the plates are fully charged (cell voltage 2.5 to 2.7, Positive-Cadmium 2.4 volts, Negative-Cadmium minus 0.15 to 0.20 volts), you will know that there is not enough acid in the electrolyte. The thing to do then is to dump out the old electrolyte, refill with 1.300 electrolyte and continue the charge until the specific gravity becomes constant. Some adjustment may then have to be made by drawing off some of the electrolyte with a hydrometer and adding water to lower the gravity, or 1.400 acid to bring it up. Remember that specific gravity readings tell you nothing about the plates, unless it is known that the electrolyte contains the correct proportions of water and acid. The cadmium test is the test which tells you directly whether or not the plates are charged and in charging a battery the aim is to charge the plates, and not merely to bring the specific gravity to 1.280.

If the specific gravity will not rise to 1.280 and cadmium tests show that the plates will not take a full charge, then the battery is, of course, defective in some way. If the battery is an old one, the negatives are probably somewhat granulated, the positives have probably lost much of their active material, resulting in a considerable amount of sediment in the jars, and the separators are worn out, carbonized, or clogged with sediment. Such a battery should not be expected to give as good service as a new one, and the best thing to do if the tests show the battery to be more than half charged, is to put it back on the car, taking care to explain to the owner why his battery will not "come up" and telling him that he will soon need a new battery. Remember that improperly treated separators, or defective separators will cause poor Negative-Cadmium readings to be obtained.

If a fairly new battery will not take a full charge, as indicated by hydrometer readings and cadmium tests, some trouble has developed due to neglect, abuse, or defect in manufacture. If all cells of a fairly new battery fail to take a full charge within 48 hours, the battery has probably been abused by failing to add water regularly, or by allowing battery to remain in an undercharged condition. Such a battery should be kept on the line for several days more, and if it then still will not take a full charge the owner should be told what the condition of the battery is, and advised to have it opened for inspection.

If one cell of a battery fails to take a charge, but the other cells charge satisfactorily, and cadmium tests show that the plates of this cell are not taking a charge, the cell should be opened for inspection. If one cell of a battery charges slowly, cut the other cells out of the line, and charge the low cell in series with the other batteries on the charging line.

If all cells of a battery, whether new or old, will not take even half a charge, as indicated by hydrometer readings (1.200), the battery should be opened for inspection.

If the gravity of a battery on charge begins to rise long before the voltage rises, and if the gravity rises above 1.300, there is too great a proportion of acid in the electrolyte. The remedy is to dump out the electrolyte, refill with pure water and continue the charge at a lower rate than before, until the specific gravity stops rising. Then charge for ten hours longer, dump out the water (which has now become electrolyte by the acid formed by the charging current), refill with about 1.350 electrolyte and continue the charge, balancing the gravity if necessary at the end of the charge.

If a battery becomes very hot while on charge at a rate which is not normally too high for the battery, it indicates that the battery is badly sulphated, or has a partial short-circuit. Gassing generally goes with the high temperature.

If you can detect a vinegar-like odor rising from the vent holes, you may be absolutely sure that the separators used in that battery have developed acetic acid due to not having received the proper treatment necessary to prepare them for use in the battery. The electrolyte should be dumped from such a battery immediately and the battery should be filled and rinsed with water several times. Then the battery should be opened without loss of time, to see whether, by removing the separators and washing the plates thoroughly, the plates may be saved. If the acetic acid has been present for any length of time, however, the plates will have been ruined beyond repair, the lead parts being dissolved by the acid.

If the electrolyte of a battery on charge has a white, milky look, there may be impurities which cause numerous minute bubbles to form, such bubbles giving the electrolyte its milky appearance. The milky appearance may be due to the use of "hard" water in refilling, this water containing lime.

The electrolyte as seen with the acid of an electric lamp or flashlight should be perfectly clear and colorless. Any scum, particles of dirt, any color whatsoever shows that the electrolyte is impure. This calls for dumping out the electrolyte, filling and rinsing with pure water, refilling with new electrolyte and putting the battery back on the charging line. Of course, this may not cause the battery to charge satisfactorily, which may be due to the troubles already described.

Should it ever happen that it is impossible to send a current through a charging circuit go over all the connections to make sure that you have good contact at each battery terminal, and that there are no loose inter-cell connectors. If all connections to the batteries are good, and there are no loose inter-cell connectors, cut out one battery at a time until you start the current flowing, when you cut out some particular battery. This battery should then be opened without further tests, as it is without a doubt in a bad condition.

The conditions which may exist when a battery will not charge, as shown especially by cadmium tests, are as follows:

(a) The battery may have been allowed to remain in a discharged condition, or the owner may have neglected to add water, with the result that the electrolyte did not cover the plates. In either case a considerable amount of crystallized sulphate will have formed in the plates. Plates in such a condition will require a charge of about a week at a low rate and will then have to be discharged and recharged again. Several such cycles of charge and discharge may be necessary. It may even be impossible to charge such a battery, no matter how many cycles of charge and discharge are given. If the owner admits that his battery has been neglected and allowed to stand idle for a considerable time, get his permission to open the battery.

(b) The battery may have been overheated by an excessive charging rate, or by putting it on a car in a sulphated condition. The normal charging rate of the generator on the car will over heat a sulphated battery. Overheated plates buckle their lower edges cut through the separators, causing a short-circuit between plates.

(c) The pockets in the bottoms of the jars may have become filled with sediment, and the sediment may be short-circuiting the plates.

(d) Impurities may have attacked the plates and changed the active materials to other substances which do not form a battery. Such plates may be so badly damaged that they are brittle and crumbled. Acetic acid from improperly treated separators will dissolve lead very quickly, and may even cause an open circuit in the cell.

(e) The conditions described in (a), (b), and (c) will permit a charging current to pass through the battery, but the plates will not become charged. It is possible, of course, but not probable, that a condition may exist in which all the plates of one or both groups of a cell may be broken from the connecting straps, or inter-cell connectors may be making no contact with the posts. In such a case, it would be impossible to send a charging current through the battery. Acetic acid from improperly treated separators, and organic matter introduced by the use of impure water in refilling will attack the lead of the plates, especially at the upper surface of the electrolyte, and may dissolve all the plate lugs from the connecting straps and cause an open-circuit.

(f) The separators may be soggy and somewhat charred and blackened, or they may be clogged up with sulphate, and the battery may need new separators.

(g) The spongy lead may be bulged, or the positives may be buckled. The active material is then not making good contact with the grids, and the charging current cannot get at all the sulphate and change it to active material. The remedy in such a case is to press the negatives so as to force the active material back into the grids, and to put in new positives if they are considerably buckled.

(h) One of the numerous "dope" electrolytes which are offered to the trustful car owner may have been put in the battery. Such "dopes" might cause very severe damage to the plates. Tell your customers to avoid using such "dope."

The conditions which may exist when the plates of a battery take a charge, as indicated by cadmium tests, but the gravity will not come up to 1.280 are as follows:

(a) There may be considerable sediment in the jars but not enough to short circuit the plates. If the battery has at some time been in a sulphated condition and has been charged At too high a rate, the gassing that resulted will have caused chips of the sulphate to drop to the bottom of the jars. When this sulphate was formed, some of the acid was taken from the electrolyte, and if the sulphate drops from the plates, this amount of acid cannot be recovered no matter how long the charge is continued. If the owner tells you that his battery has stood idle for several months at some time, this is a condition which may exist. The remedy is to wash and press the negatives, wash the positives, put in new separators, pour out the old electrolyte and wash out the jars, fill with 1.400 acid, and charge the battery.

(b) Impurities may have used up some of the acid which cannot be recovered by charging. If the plates are not much damaged the remedy is the same as for (a). Damaged plates may require renewal.

(c) Electrolyte may have been spilled accidentally and replaced by water.

(d) Too much water may have been added, with the result that the expansion of the electrolyte due to a rise in temperature on charge caused it to overflow. This, of course, resulted in a loss of some of the acid.

The causes given in (c) and (d) may have resulted in the top of the battery case being acid-eaten or rotted. The remedy in these two instances is to draw off some of the electrolyte, add some 1.400 acid and continue the charge. If plates and separators look good and there is but little sediment, this is the thing to do.

If Battery will not hold a Charge. If a battery charges properly but loses its charge in a week or less, as indicated by specific gravity readings, the following troubles may exist:

(a) Impurities in the cells, due to the use of impure water in the electrolyte, or in the separators. Some impurities (see page 76) do not attack the plates, but merely cause self-discharge. The remedy is to dump out the old electrolyte, rinse the jars with pure water, fill with new electrolyte of the same gravity as the old and recharge. If this does not remove impurities, the battery should be opened, the plates washed, jars cleaned out, new separators put in, and battery reassembled and charged.

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