The Automobile Storage Battery Part 53

The final specific gravity must be between 1.280 and 1.300. In measuring the specific gravity the temperature must be about 70F., or else corrections must be made. For every three degrees above 70, add one point (.001) to the reading you obtain on the hydrometer. For every three degrees under 70, subtract one point (.001) from the reading you obtain on the hydrometer. For instance, if you read a specific gravity of 1.275 and find that the temperature of the electrolyte is 82F., add ((82-70)/3 = 4)four points (1.275 + .004), which gives 1.279, which is what the specific gravity of the electrolyte would be if its temperature were lowered to 70. The reason this is done is that when Ave speak of an electrolyte of a certain specific gravity, say 1.280, we mean that this is its specific gravity when its temperature is 70F. We must therefore make the temperature correction if the temperature of the electrolyte is much higher or lower than 70F.

Putting on The Covers

This operation is a particular one, and must be done properly, or you will come to grief. Get the box containing the covers and connectors for the battery you are working on; take the covers, and clean them thoroughly. There are several ways to clean them. If you have gasoline at hand, dip a brush in it and scrub off the compound. The covers may also be cleaned off with boiling water, but even after you have used the hot water, it will be necessary to wipe off the covers with gasoline. Another way to soften any compound which may be sticking to them, is to put the covers in the Battery Steamer and steam them for about ten minutes. This will also heat the covers and make them limp so that they may be handled without breaking.

If the covers fit snugly all around the inside of the jars so that there is no crack which will allow the compound to run down on the elements, all is well and good. If, however, there are cracks large enough to put a small, thin putty knife in, you must close them. If the cracks are due to the tops of the jars being bent out of shape, heat the tops with a soft flame until they are limp, (be careful not to burn them). Now, with short, thin wedges of wood, (new dry separators generally answer the purpose), crowd down on the outside edges of the jar, until you have the upper edge of jars straight and even all around. If the jars are set in compound, take a hot screwdriver and remove the compound from between the jar and case near the top. If the cracks between cover and jar still remain, calk them with asbestos packing, tow, or ordinary wrapping string. Do not use too much packing;--just enough to close the cracks is sufficient.

When this is done, see that the top of the case is perfectly level, so that when the compound is poured in, it will settle level all around the upper edge of the case.

Sealing Compounds

There are many grades of compounds (see page 149), and the kind to use must be determined by the type of battery to be sealed. There is no question but that a poor grade used as carefully as possible will soon crack and produce a slopper. A battery carelessly sealed with the best compound is no better.

The three imperative conditions for a permanent lasting job are:

1. Use the best quality of the proper kind of compound for sealing the battery on hand.

2. All surfaces that the compound comes in contact with must be free from acid and absolutely clean and dry.

3. The sealing must be done conscientiously and all details properly attended to step by step, and all work done in a workmanlike manner.

With respect to sealing, batteries may be divided into two general cla.s.ses. First, the old type battery with a considerable amount of sealing compound. This type of battery generally has a lower and an upper cover, the vent tube being attached or removable, depending on the design. The compound is poured on top of the lower cover and around the vent tube, and the top covers are then put on. Most of the batteries of this type have a thin hard rubber sleeve shrunk on the post where the compound comes in contact with it; this hard rubber sleeve usually has several shallow grooves around it which increase its holding power. This is good construction, provided everything else is normal and the work properly done with a good stick-, compound.

There are a few single cover batteries with connecting straps close to top of covers, and the compound is poured over the top of the straps.

See Fig. 262.

The second general type consists of single one-piece cover batteries that have small channels or s.p.a.ces around the covers next to the jars into which the sealing compound is poured. This type of battery is the most common type.

[Fig. 229 Pouring compound on lower covers]

Compound in bulk or in thin iron barrels can be cut into small pieces with a hatchet or hand ax. To cut off a piece in hot weather, strike it a quick hard blow in the same place once or twice, and a piece will crack off. Directions for properly beating sealing compound will be found on page 150.

Sealing Double Cover Batteries

The following instructions apply to batteries having double covers.

These are more difficult to seal than the single cover batteries. If you can seal the double cover batteries well, the single cover batteries will give you no trouble.

Always start the fire under the compound before you are ready to use it, and turn the fire lower after it has melted, so as not to have it too hot at the time of pouring. If you have a special long nosed pouring ladle, fill it with compound by dipping in the pot, or by pouring compound from a closed vessel. If you heat the compound in an iron kettle, pour it directly into pouring ladle, using just about enough for the first pouring. The compound should not be too hot, as a poor sealing job battery will result from its use. See page 150.

Before sealing, always wipe the surfaces to be sealed with a rag wet with ammonia or soda solution, rinsed with water, and wiped dry with a rag or waste. If you fail to do this the compound will not stick well, and a top leak may develop. Then run a soft lead burning flame over the surfaces to be sealed, in order to have perfectly dry surfaces.

Remember that sealing compound will not stick to a wet surface.

[Fig. 230 First pouring of sealing compound]

[Fig. 231 Cooling compound with electric fan]

Pour compound on the lower covers, as in Fig. 229. Use enough to fill the case just over the tops of the jars, Fig. 230. Then pour the rest of the compound back in compound vessel or kettle. To complete the job, and make as good a job as possible, take a small hot lead burning flame and run it around the edges of case, tops of jars, and around the posts until the compound runs and makes a good contact all around.

If you have an electric fan, let it blow on the compound a few minutes to cool it, as in Fig. 231. Then the compound used for the second pouring may be hotter and thinner than the first.

Fill the pouring ladle with compound, which is thinner than that used in the first pouring, and pour within 1/16 inch of the top of the case, being careful to get in just enough, so that-after it has cooled, the covers will press down exactly even with the top of the case, Fig. 232. It will require some experience to do this, but you will soon learn just how much to use.

As soon as you have finished pouring, run the flame all around the edges of the case and around the post, being very careful not to injure any of the vent tubes. A small, hot-pointed flame should be used. Now turn on the fan again to cool the compound.

[Fig. 232 Second pouring of sealing compound]

While the compound is cooling, get the cell connectors and terminal connectors, put them in a two-quart granite stew pan, just barely cover with water, and sprinkle a tablespoon of baking soda over them.

Set the stew pan over the fire and bring water to boiling point. Then pour the water on some spot on a bench or floor where the acid has been spilled. This helps to neutralize the acid and keep it from injuring the wood or cement. Rinse off the connectors and wipe them dry with a cloth, or heat them to dry them.

[Fig. 233 Pressing covers down to make them level with top of case]

Now take the top covers, which must be absolutely clean and dry, and spread a thin coat of vaseline over the top only, wiping off any vaseline from the beveled edges. Place these covers right side up on a clean board and heat perfectly limp with a large, spreading blow torch flame. Never apply this flame to the under side of the top covers. The purpose is to get the covers on top of the battery absolutely level, and exactly even with the top of the case all around it, and to have them sticking firmly to the compound. There is not an operation in repairing and rebuilding batteries that requires greater care than this one, that will show as clearly just what kind of a workman you are, or will count as much in appearance for a finished job. If you are careless with any of the detail, if just one b.u.mp appears on top, if one top is warped, if one cover sticks above top of case, try as you may, you never can cover it up, and show you are a first-cla.s.s workman. See that you have these four conditions, and you should not have any difficulty after a little experience:

[Fig. 234 Pressing covers down around posts to make them flush with top of case]

1. You must have just enough compound on top to allow the top covers to be pressed down exactly even with upper edge of case.

2. The top covers must be absolutely clean and have a thin coat of vaseline over their top, but none on the bevel edge.

3. A good sized spreading flame to heat quickly and evenly the tops to a perfectly limp condition without burning or scorching them.

4. Procure a piece of 7/8-inch board 1-1/2 inches wide and just long enough to go between handles of battery you are working on. Spread a thin film of oil or vaseline all over it.

Having heated the covers and also the top surface of the compound until it is sticky so that the covers may be put down far enough and adhere firmly to it, place the covers in position. Then press the covers down firmly with a piece of oiled wood, as in Fig. 233, applying the wood sidewise and lengthwise of case until the top of cover is exactly even with the top of the case. It may be necessary to use the wood on end around the vent tubes and posts as in Fig. 234, to get that part of the cover level. If the compound comes up between covers and around the edges of the case, and interferes with the use of the wood, clean it out with a screwdriver. You can then finish without smearing any compound on the covers.

[Fig. 235 Wiping bottom of spoon filled with sealing compound]

[Fig. 236 Filling cracks around covers with sealing compound]

When you have removed the excess compound from the cracks around the edges of the covers with the screwdriver, take a large iron spoon which has the end bent into a pouring lip, and dip up from 1/2 to 2/3 of a spoonful of melted compound (not too hot). Wipe off the bottom of the spoon, Fig. 235, and pour a small stream of compound evenly in all the cracks around the edges of the covers until they are full, as in Fig. 236. Do not hold the spoon too high, and do not smear or drop any compound on top of battery or on the posts. No harm is done if a little runs over the outside of the case, except that it requires a little time to clean it off. A small teapot may be used instead of the spoon. If you have the compound at the right temperature, and do not put in too much at a time, you will obtain good results, but you should take care not to spill the compound over covers or case.

[Fig. 237 Final operation of cleaning off excess compound]

After the last compound has cooled,--this requires only a few minutes,--take a putty knife, and sc.r.a.pe off all the surplus compound, making it even with the top of the covers and case, Fig.

.237. Be careful not to dig into a soft place in the compound with the putty knife. If you have done your work right, and have followed directions explicitly, you have sc.r.a.ped off the compound with one sweep of the putty knife over each crack, leaving the compound smooth and level. You will be surprised to see how finished the battery looks.

Some workmen pour hot compound clear to the top of the case and then hurry to put on a cold, dirty top. What happens? The underside of the cover, coming in contact with the hot compound, expands and lengthens out, curling the top surface beyond redemption. As you push down one corner, another goes up, and it is impossible to make the covers level.

Sealing Single Cover Batteries

Single cover batteries are scaled in a similar manner. The covers are put in place before any compound is poured in. Covers should first be steamed to make them soft and pliable. The surfaces which come in contact with the sealing compound must be perfectly dry and free from acid. Before pouring in any compound, run a soft flame over the surfaces which are to be sealed, so as to dry them and warm them.

Close up all cracks between Jars and covers as already directed. Then pour the cover channels half full of sealing compound, which must not be too thin. Now run a soft flame over the compound until it flows freely and unites with the covers and jars. Allow the compound to cool.