The Automobile Storage Battery Part 38

The rates of discharge given here for the "starting-ability" tests may be varied if experience with a particular make of battery shows some other rate to be better. The important thing is to use the same rate of discharge for the same make and type of battery at all times. In this way the repairman will soon be able to distinguish between good and bad batteries of a particular make and type.

Cadmium Tests may be made during the Starting Ability Discharge Tests.

See page 174.

"Cycling" Discharge Tests

New batteries, or rebuilt batteries which have had new plates installed, or sulphated batteries which will not "come up" on charge, should be discharged when they have "come-up," as far as they will go.

In some cases it is necessary to charge and discharge them several times before they will be ready for service. This charging and discharging is often called "cycling" the battery.

New batteries are generally "cycled" at the factory before sending them out. The forming charge generally does not convert all the pastes into active material and the battery using plates which have been treated in the forming room is put through several discharges and charges after the battery is fully a.s.sembled. In service on a car, the battery is being "cycled" constantly and there is generally an increase in capacity after a battery is put on a car. Positive plates naturally increase in capacity, sometimes up to the very clay when they fall to pieces, while negatives tend to lose capacity with age.

Batteries which are a.s.sembled in the service station, using new plates, generally require several cycles of charge and discharge before the specific gravity will rise to 1.280 before the positives will give 2.4-2.5 volts on a Cadmium test, before the negatives will give a reversed voltage reading of 0.175 to 0.20 volt on a Cadmium test, and before a satisfactory "starting-ability" or "breakdown" test can be made.

A battery which has been abused by failing to add water to replace evaporation, by allowing to remain in a partially or completely discharged condition for sometime, or which has been allowed to become sulphated in any other way, will generally require "cycling" before it will "come-up" to a serviceable condition.

The rates for a "cycling" discharge should be such that the battery will be discharged during the daytime, the discharge being started in the morning, and the battery being put back oil the charging line in the evening in order that it may be charging during the night. The rate of discharge should be somewhat higher than the rate used when the plates are formed. Two or three amperes per positive plate in each cell will generally be satisfactory.

Discharge Apparatus

A simple discharge rheostat is shown in Fig. 180. The terminal on the end of the cable attached to the right hand terminal of the battery shown in the ill.u.s.tration is movable, and it may be clamped at any point along the coils of wire so as to give various currents. The wire should be greased lightly to prevent rusting.

[Fig. 180 Simple high rate discharge rheostat]

Another simple apparatus consists of a board on which are mounted six double contact automobile lamp sockets which are all connected in parallel. A pair of leads having test clips attached is brought out from the sockets for fastening to the battery terminals. Lamps of various candlepower may be turned into the sockets to obtain different currents.

Discharge tests are helpful in the case of a battery that has lost capacity. The battery is first fully charged, and is then discharged at the 5 hour rate. When the voltage of the battery has fallen to 1.7 volts per cell (measured while the battery is discharging) a Cadmium test is made to determine whether the positives or negatives are causing the lack of capacity. For further descriptions of the Cadmium Test see Page 174.

In reviving sulphated batteries, it is sometimes necessary to charge and discharge the battery several times to put the active material in a healthy condition.

Discharge tests at a high rate are very valuable in diagnosing the condition of a battery. A description of such tests will be found on Page 267. For making the heavy discharge tests a rheostat of the carbon plate type is suitable. With such a rheostat currents from 25 to more than 200 may be drawn from a six volt battery, and a smooth, even variation of a current may be obtained from the minimum to the maximum values. Such a rheostat is on the market and may be purchased complete with ammeter and leads for attaching to the battery.

PACKING BATTERIES FOR SHIPPING

Batteries which are shipped without electrolyte need merely have plenty of excelsior placed around them in a strong crate for protection from mechanical injury.

Batteries which are shipped filled with electrolyte must be protected from mechanical injury and must also be packed so that it is difficult to turn the crate upside down and thus allow the electrolyte to run out. A very popular crate has been the so-called "dog-house," with a gable roof such as is actually used on dog-houses. The idea of such a roof is that it is impossible to place the crate with the roof down, since it will tip over if this is done. However, if these crates are placed side by side, it is a very simple matter to put a second row of crates on top of them, turning the second row up-side-down, as shown in Fig. 181, and allowing the electrolyte to run out. The men who load freight or express-cars have often shown great skill and cunning in packing "dog-house" crates in other ways so as to damage the batteries. Many have attained a high degree of perfection in breaking the crates.

[Fig. 181 "Dog-house" crates for shipping batteries]

Some sort of a roof on a battery crate is required by law, the idea being to make it difficult to turn the crate up-side-down. Perhaps the best crate would be one with a flat top marked "This Side Up," but such a crate would not comply with the law.

[Fig. 182 Steps for construction of a crate for shipping battery]

A better form of crate than the "dog-house" and one which complies with the law, is shown in Fig. 182. The top of each end piece is cut at an angle, the peak on one end being placed opposite the low point of the opposite end piece. Fig. 182 shows the steps in the construction of the crate.

1. The case should be built of strong lumber (11/2 inch preferably), and of ample size to allow packing with excelsior top, bottom, sides and ends to a thickness of two or three inches. Nail strongly.

2. When the case is complete (except cover) place a thick, even layer of excelsior (or packing straw) in the bottom and set in *he battery right side up. Lay paper (preferably paraffined) over top of battery to keep it clean, then pack tightly with excelsior sides and ends.

3. Now lay sufficient packing material on top of the battery so that cover will compress it tightly, stuffing it under cover boards as they are put on.

The extended boards at bottom, and the gable roof are provided to prevent the battery from being tipped over; extensions of sides for carrying. Box should be plainly labeled: "HANDLE WITH CARE. DAMAGES CLAIMED IF TIPPED ON SIDE." In addition to the address of destination, as given in shipping instructions be sure to mark with name of shipper for identification upon arrival. When shipping by freight, the proper freight cla.s.sification in the United States is "Electric Storage Batteries, a.s.sembled." When shipping by express in the United States, "Acid" caution labels must be attached to each package.

STORING SEPARATORS

Separators which have been given the chemical treatment necessary to remove the substances which would cause trouble in the battery, and to make the wood porous, must be kept wet and never be allowed to become dry. A lead lined box, or large earthenware jars may be used as containers. Put the separators in the container and then pour in enough very weak electrolyte to cover the separators. This electrolyte may be made of I part of 1.220 electrolyte to 10 parts of distilled water, by volume. Be very careful to have the container absolutely clean and to use chemically pure acid and distilled water in making the weak electrolyte. Remember that impurities which are picked up by the separators will go into the battery in which the separators are placed. Therefore, keep the separator tank in a clean place and keep a cover on it. Have your hands clean when you take separators out of the tank to place in a battery, and do not put the separators on a dirty bench before inserting them between plates. The best thing to do is to hold the separators in one hand and insert them with the other, and not lay them on any bench at all.

REINSULATION

Separators are the weakest part of a battery and wear out while the other parts of a battery are still in good condition. Good plates are often ruined by weakened separators causing short-circuits. Many batteries which have to be junked after being in service about a year would have given considerable service if they had been reinsulated.

Generally the separators of one cell wear out before those of the other cells. Do not, however, reinsulate that cell alone. The separators in the other cells are as old as those which have worn out, and are very near the breaking down point. If you reinsulate only one cell, the owner will naturally a.s.sume that the other cells are in good condition. What happens? A month or so later one of the other cells "goes dead." This does not have a very soothing effect on the owner, who will begin to lose confidence in you and begin to look around for another service station.

If you explain frankly that it is useless to reinsulate only one cell of a battery and that the other cells will break down in a short time, the customer will want you to reinsulate all the cells. A somewhat higher bill for reinsulating all the cells at once will be more agreeable than having the cells break down one at a time within a month or two.

In the case of the customers who come in regularly for testing and filling service, you will be able to tell when the separators are wearing out. When you find that a battery which has been in service about a year begins to run down frequently, and successive tests made in connection with testing and filling service show that the generator is not able to keep the battery charged, advise the owner to have the battery reinsulated. Do not wait for the battery to have a dead cell.

Sell the owner on the idea that reinsulation will prevent the possibility of his battery breaking down when he may be out on a tour, and when it may be necessary to have his car towed in to a service station. If you allow the battery to remain on the car when it begins to lose its charge, the owner will not, of course, suspect that anything is wrong, and if his battery one day breaks down suddenly, lie will very likely lose confidence both in you and the battery, since he has been bringing in his car regularly in order to have his battery kept in good shape. The sudden failure of his battery will, therefore, make him believe that you do not know your business, or that the battery is a poor one.

New separators will give every battery which is a year old a new lease on life. If you explain to a customer that he will get a much longer period of service from his battery if he has it reinsulated when the battery is a year old, you should have no trouble in getting the job, and the subsequent performance of the battery will show that you knew what you were talking about.

SAFETY FIRST FOR THE BATTERY REPAIRMAN

1. Do not work on an empty stomach-you can then absorb lead easily.

2. Keep your fingers out of your mouth when at work.

3. Keep your finger nails short and clean.

4. Do not chew tobacco while at work. In handling tobacco, the lead oxides are carried to your mouth. Chewing tobacco does not prevent you from swallowing lead.

5. When you leave the shop at night, and before eating, wash your face, hands, and arms with soap, and clean your nose, mouth, and finger nails.

6. Do not eat in the repair shop.

7. Drink plenty of good milk. It prevents lead poisoning.