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CHAPTER XII - BATTERY CHARGING DEVICES
The automatic plant most desirable—How an automobile lighting and starting system works—How the same results 
can be achieved in house lighting, by means of automatic devices—Plants without automatic regulation—Care 
necessary—The use of heating devices on storage battery current—Portable batteries—An electricity "route"—
Automobile power for lighting a few lamps.

The water-power electric plants described in preceding chapters are practically automatic in operation. This is very 
desirable, as such plants require the minimum of care. It is possible to attain this same end with a storage battery 
plant.

Automatic maintenance approaches a high degree of perfection in the electric starting and lighting device on a 
modern automobile. In this case, a small dynamo geared to the main shaft is running whenever the engine is 
running. It is always ready to "pump" electricity into the storage battery when needed. An electric magnet, wound in 
a peculiar manner, automatically cuts off the charging current from the dynamo, when the battery is "full;" and the 
same magnet, or "regulator," permits the current to flow into the battery when needed. The principle is the same as 
in the familiar plumbing trap, which constantly maintains a given level of water in a tank, no matter how much water 
may be drawn from the tank. The result, in the case of the automobile battery, is that the battery is always kept fully 
charged; for no sooner does the "level" of electricity begin to drop (when used for starting or lighting) than the
generator begins to charge. This is very desirable in more ways than one. In the first place, the energy of the 
battery is always the same; and in the second place, the mere fact that the battery is always kept fully charged 
gives it a long life.

The same result can be achieved in storage battery plants for house lighting, where the source of power is a 
gasoline or other engine engaged normally in other work. Then your electric current becomes merely a by-product 
of some other operation.

Take a typical instance where such a plant would be feasible: Farmer Brown has a five horsepower gasoline 
engine—an ordinary farm engine for which he paid probably $75 or $100. Electric light furnished direct from such 
an engine would be intolerable because of its constant flickering. This five horsepower engine is installed in the 
milk room of the dairy, and is belted to a countershaft. This countershaft is belted to the vacuum pump for the 
milking machine, and to the separator, and to a water pump, any one of which may be thrown into service by 
means of a tight-and-loose pulley. This countershaft is also belted to a small dynamo, which runs whenever the 
engine is running. The milking machine, the separator, and the water pump require that the gasoline engine be run 
on the average three hours each day.

The dynamo is connected by wires to the house storage battery through a properly designed switchboard. The 
"brains" of this switchboard is a little automatic device (called a regulator or a circuit breaker), which opens and 
shuts according to the amount of current stored in the battery and the strength of the current from the generator. 
When the battery is "full," this regulator is "open" and permits no current to flow. Then the dynamo is running idle, 
and the amount of power it absorbs from the gasoline engine is negligible. When the "level" of electricity in the 
battery falls, due to drawing current for light, the regulator is "shut," that is, the dynamo and battery are connected, 
and current flows into the battery.

These automatic instruments go still farther in their brainy work. They do not permit the dynamo to charge the 
battery when the voltage falls below a fixed point, due to the engine slowing down; neither do they permit the 
dynamo current to flow when the voltage gets too high due to sudden speeding up of the engine.

Necessarily, an instrument which will take[Pg 254] care of a battery in this way, is intricate in construction. That is 
not an argument against it however. A watch is intricate, but so long as we continue to wind it at stated intervals, it 
keeps time. So with this storage battery plant: so long as Farmer Brown starts his engine to do his farm chores 
every day, his by-product of electricity is stored automatically.

Such installations are not expensive. A storage battery capable of lighting 8 tungsten lamps, of 16 candlepower 
each, continuously for 8 hours (or fewer lamps for a longer time); a switchboard containing all the required 
regulating instruments; and a dynamo of suitable size, can be had for from $250 to $300. All that is necessary to 
put such a plant in operation, is to belt the dynamo to the gasoline engine so that it will run at proper speed; and to 
connect the wires from dynamo to switchboard, and thence to the house service. The dynamo required for the 
above plant delivers 10 amperes at 45 volts pressure, or 10 × 45 = 450 watts. A gasoline, gas, or oil engine, or a 
windmill of 1½ horsepower furnishes all the power needed. If the farmer uses his engine daily, or every other day, 
for other purposes, the cost of power will be practically negligible. With this system electric lights are available at 
any time day or night; and when the gasoline engine is in service daily for routine farm chores, the battery will 
never run low.

This system is especially desirable where one uses a windmill for power. The speed of the windmill is constantly 
fluctuating, so much so in fact that it could not be used for electric light without a storage battery. But when 
equipped with a regulator on the switchboard which permits the current to flow only when the battery needs it, and 
then only when the speed of the windmill is correct, the problem of turning wind power into electric light is solved.

If the farmer does not desire to go to the additional expense of automatic regulation, there are cheaper plants, 
requiring attention for charging. These plants are identical with those described above, except they have no 
regulators. With these plants, when the battery runs low (as is indicated by dimming of the lights) it is necessary to 
start the engine, bring it up to speed, adjust the dynamo voltage to the proper pressure, and throw a switch to 
charge the battery. For such plants it is customary to run the engine to charge the battery twice a week. It is 
necessary to run the engine from 8 to 10 hours to fully charge the discharged battery. When the battery 
approaches full charge, the fact is evidenced by so-called "gassing" or giving off of bubbles. Another way to 
determine if the battery is fully charged is by means of the voltmeter, as the volts slowly rise to the proper point 
during the process of charging. A third way, and probably the most reliable is by the use of the hydrometer. The 
voltage of each cell when fully charged should be 2.5; it should never be discharged below 1.75 volts. Many 
storage battery electric light plants on the market are provided with a simple and inexpensive circuit breaker, which 
automatically cuts off the current and stops the engine when the battery is charged. The current is then thrown 
from the dynamo to the house service by an automatic switch. If such a circuit breaker is not included, it is 
necessary to throw the switch by hand when charging is begun or ended.

Since the principal item of first cost, as well as depreciation, in a storage battery electric light plant is the storage 
battery itself, the smallest battery commensurate with needs is selected. Since the amount of current stored by 
these batteries is relatively small, electric irons and heating devices such as may be used freely on a 
direct-connected plant without a battery, are rather expensive luxuries. For instance, an electric iron drawing 400 
watts an hour while in use, requires as much energy as 20 tungsten lamps of 16 candlepower each burning for the 
same length of time. Its rate of current consumption would be over 13 amperes, at 30 volts; which would require a 
larger battery than needed for light in the average farm home.

The use to which electricity from a storage battery is put, however, is wholly a matter of expense involved; and if 
one is willing to pay for these rather expensive luxuries, there is no reason why he should not have them. Heating, 
in any form, by electricity, requires a large amount of current proportionally. As a matter of fact, there is less heat to
be had in thermal units from a horsepower-hour of electricity than from three ounces of coal. When one is 
generating current from water-power, or even direct from gasoline or oil, this is not an argument against electric 
heating devices. But it becomes a very serious consideration when one is installing a storage battery as the source 
of current, because of the high initial cost, and depreciation of such a battery.

Farmers who limit the use of their storage battery plants to lighting will get the best service.

Portable Batteries
Abroad it is becoming quite common for power companies to deliver storage batteries fully charged, and call for 
them when discharged. Without a stretch of the imagination, we can imagine an ingenious farmer possessing a 
water-power electric plant building up a thriving business among his less fortunate neighbors, with an "electricity" 
route. It could be made quite as paying as a milk route.

Connections for charging storage batteries on 110-volt mains

Many communities have water or steam power at a distance too great to transmit 110-volt current by wire 
economically; and because of lack of expert supervision, they do not care to risk using current at a pressure of 500 
volts or higher, because of its danger to human life.

In such a case it would be quite feasible for families to wire their houses, and carry their batteries to the generating 
plant two or three times a week to be charged. There are a number of portable batteries on the market suitable for 
such service, at voltages ranging from 6 to 32 volts. The best results would be obtained by having two batteries, 
leaving one to be charged while the other was in use; and if the generating station was located at the creamery or 
feed mill, where the farmer calls regularly, the trouble would be reduced to a minimum.

Such a battery would necessarily be small, and of the sealed type, similar to those used in automobiles. It could be 
used merely for reading lamps—or it could be used for general lighting, according to the expense the farmer is 
willing to incur for batteries.

An ordinary storage battery used in automobile ignition and lighting systems is of the 6-volt, 60-ampere type, 
called in trade a "6-60." Lamps can be had for these batteries ranging in sizes from 2 candlepower to 25 
candlepower. A lamp of 15 candlepower, drawing 2½ amperes, is used for automobile headlights, and, as any one 
knows after an experience of meeting a headlight on a dark road, they give a great deal of light. A "6-60" battery 
keeps one of these lamps running for 24 hours, or two lamps running 12 hours. A minimum of wiring would be 
required to install such a battery for the reading lights in the sitting room, and for a hanging light in the dining room.
The customary gates for charging these batteries in a large city is 10 cents; but in a country plant it could be made 
less.

To charge such a battery on a 110-volt direct current, it is necessary to install some means of limiting the amount 
of current, or in other words, the charging rate. This charging rate, for 8 hours should be, as we have seen, 
one-eighth of the ampere-hour capacity of the battery. Thus a "6-60" battery would require a 7½ ampere current.

Connecting two such batteries in "series" (that is, the negative pole of one battery to the positive pole of the 
second) would make a 12-volt battery. Ten or twelve such batteries could be connected in "series," and a 110-volt 
direct current generator would charge them in 8 hours at a 7½ ampere rate.

The diagram on page 259 shows the connections for charging on a 110-volt circuit.

An ordinary 16-candlepower carbon lamp is of 220 ohms resistance, and (by Ohm's Law, C equals E divided by R) 
permits ½ ampere of current to flow. By connecting 15 such lamps across the mains, in parallel, the required 7½ 
amperes of current would be flowing from the generator through the lamps, and back again. Connect the battery in 
"series" at any point on either of the two mains, between the lamps and the generator, being careful to connect the 
positive end to the positive pole of the battery, and vice versa.

Lamps are the cheapest form of resistance; but in case they are not available, any other form of resistance can be 
used. Iron wire wound in spirals can be used, or any of the many makes of special resistance wire on the market. 
First it is necessary to determine the amount of resistance required.

We have just seen that the charging rate of a 60-ampere hour battery is 7½ amperes. Applying Ohm's Law here, 
we find that ohms resistance equals volts divided by amperes, or R = 110/7.5 = 14.67 ohms. With a 220-volt 
current, the ohms resistance required in series with the storage battery of this size would be 29.33 ohms.

Automobile Power for Lighting
There are many ingenious ways by which an automobile may be utilized to furnish electric light for the home. The 
simplest is to run wires direct from the storage battery of the self-starting system, to the house or barn, in such a 
way that the current may be used for reading lamps in the sitting room. By a judicious use of the current in this way,
the normal operation of the automobile in the daytime will keep the battery charged for use of the night lamps, and 
if care is used, such a plan should not affect the life of the battery. Care should be used also, in this regard, not to 
discharge the battery too low to prevent its utilizing its function of starting the car when it was desired to use the 
car. However, if the battery were discharged below its starting capacity, by any peradventure, the car could be 
started by the old-fashioned cranking method.

Using an automobile lighting system for house lighting implies that the car be stored in a garage near the house or 
barn; as this battery is too low in voltage to permit transmitting the current any distance. One hundred feet, with 
liberal sized transmission wires is probably the limit.

That such a system is feasible is amply proved by an occurrence recently reported in the daily papers. A doctor 
summoned to a remote farm house found that an immediate operation was necessary to save the patient's life. 
There was no light available, except a small kerosene lamp which was worse than nothing. The surgeon took a 
headlight off his car, strung a pair of wires through a window, and instantly had at his command a light of the 
necessary intensity.

Another manner in which an automobile engine may be used for house lighting is to let it serve as the charging 
power of a separate storage battery. The engine can be belted to the generator, in such a case, by means of the 
fly wheel. Or a form of friction drive can be devised, by means of which the rear wheels (jacked up off the floor) may
supply the necessary motive power. In such a case it would be necessary to make allowance for the differential in 
the rear axle, so that the power developed by the engine would be delivered to the friction drive.

End of Excerpt.
This (complete) title is available in the SSRsi Survival Library

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