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PART III - GASOLINE ENGINES, WINDMILLS, ETC. THE STORAGE BATTERIES

CHAPTER X - GASOLINE ENGINE PLANTS
The standard voltage set—Two-cycle and four-cycle gasoline engines—Horsepower, and fuel consumption—
Efficiency of small engines and generators—Cost of operating a one-kilowatt plant.

Electricity is of so much value in farm operations, as well as in the farm house, that the farmer who is not fortunate 
enough to possess water-power of his own, or to live in a community where a coöperative hydro-electric plant may 
be established, should not deny himself its many conveniences. In place of the water wheel to turn the dynamo, 
there is the gasoline engine (or other forms of internal combustion engine using oil, gas, or alcohol as fuel); in 
many districts where steam engines are used for logging or other operations, electricity may be generated as a 
by-product; and almost any windmill capable of pumping water can be made to generate enough electricity for 
lighting the farm house at small expense.

The great advantage of water-power is that the expense of maintenance—once the plant is installed—is practically 
nothing. This advantage is offset in some measure by the fact that other forms of power, gas, steam, or windmills, 
are already installed, in many instances and that their judicious use in generating electricity does not impair their 
usefulness for the other farm operations for which they were originally purchased. In recent years gasoline engines 
have come into general use on farms as a cheap dependable source of power for all operations; and windmills 
date from the earliest times. They may be installed and maintained cheaply, solely for generating electricity, if 
desired. Steam engines, however, require so much care and expert attention that their use for farm electric plants 
is not to be advised, except under conditions where a small portion of their power can be used to make electricity 
as a by-product.

There are two types of gasoline engine electric plants suitable for the farm, in general use:

First: The Standard Voltage Set, in which the engine and dynamo are mounted on one base, and the engine is 
kept running when current is required for any purpose. These sets are usually of the 110-volt type, and all 
standard appliances, such as irons, toasters, motors, etc., may be used in connection with them. Since the 
electricity is drawn directly from the dynamo itself, without a storage battery, it is necessary that these engines be 
efficient and governed as to speed within a five per cent variation from no load to full load.

Second: Storage Battery Sets, in which the dynamo is run only a few hours each week, and the electricity thus 
generated is "stored" by chemical means, in storage batteries, for use when required. Since, in this case, the 
current is drawn from the battery, instead of the dynamo, when used for lighting or other purposes, it is not 
necessary that a special type of engine be used to insure constant speed.

The Standard Voltage Set
In response to a general demand, the first type (the direct-connected standard voltage set) has been developed to 
a high state of efficiency recently, and is to be had in a great variety of sizes (ranging from one-quarter kilowatt to 
25 kilowatts and over) from many manufacturers.

The principle of the gasoline engine as motive power is so familiar to the average farmer that it needs but a brief 
description here. Gasoline or other fuel (oil, gas, or alcohol) is transformed into vapor, mixed with air in correct 
proportions, and drawn into the engine cylinder and there exploded by means of a properly-timed electric spark.

Internal combustion engines are of two general types—four-cycle and two-cycle. The former is by far the more 
common. In a four-cycle engine the piston must travel twice up and down in each cylinder, to deliver one power 
stroke. This results in one power impulse in each cylinder every two revolutions of the crank shaft. On its first down 
stroke, the piston sucks in gas. On its first up stroke, it compresses the gas. At the height of this stroke, the gas is 
exploded by means of the electric spark and the piston is driven down, on its power stroke. The fourth stroke is 
called the scavenging stroke, and expels the burned gas. This completes the cycle.

A one-cylinder engine of the ordinary four-cycle type has one power stroke for every two revolutions of the fly 
wheel. A two-cylinder engine has one power stroke for one revolution of the fly wheel; and a four-cylinder engine 
has two power strokes to each revolution. The greater the number of cylinders, the more even the flow of power. In 
automobiles six cylinders are common, and in the last year or two, eight-cylinder engines began appearing on the 
market in large numbers. A twelve-cylinder engine is the prospect for the immediate future.

Since the dynamo that is to supply electric current direct to lamps requires a steady flow of power, the 
single-cylinder gas or gasoline engine of the four-cycle type is not satisfactory as a rule. The lights will flicker with 
every other revolution of the fly wheel. This would be of no importance if the current was being used to charge a 
storage battery—and right here lies the reason why a cheaper engine may be used in connection with a storage 
battery than when the dynamo supplies the current direct for lighting.

A two-cylinder engine is more even in its flow of power and a four-cylinder engine still better. For this reason, 
standard voltage generating sets without battery are usually of two or four cylinders when of the four-cycle type. 
When a single-cylinder engine is used, it should be of the two-cycle type. In the two-cycle engine, there is one 
power stroke to each up-and-down journey of the piston. This effect is produced by having inlet and exhaust ports 
in the crank case, so arranged that, when the piston arrives at the bottom of the power stroke, the waste gases are 
pushed out, and fresh gas drawn in before the up stroke begins.

For direct lighting, the engine must be governed so as not to vary more than five per cent in speed between no 
load and full load. There are many makes on the market which advertise a speed variation of three per cent under 
normal loads. Governors are usually of the centrifugal ball type, integral with the fly wheel, regulating the amount 
of gas and air supplied to the cylinders in accordance with the speed. Thus, if such an engine began to slow down 
because of increase in load, the centrifugal balls would come closer together, and open the throttle, thus supplying 
more gas and air and increasing the speed. If the speed became excessive, due to sudden shutting off of lights, 
the centrifugal balls would fly farther apart, and the throttle would close until the speed was again adjusted to the 
load.

These direct-connected standard voltage sets are as a rule fitted with the 110-volt, direct current, compound type 
of dynamo, the duplicate in every respect of the machine described in previous chapters for water-power plants. 
They are practically automatic in operation and will run for hours without attention, except as to oil and gasoline 
supply. They may be installed in the woodshed or cellar without annoyance due to noise or vibration. It is 
necessary to start them, of course, when light or power is desired, and to stop them when no current is being 
drawn. There have appeared several makes on the market in which starting and stopping are automatic. Storage 
batteries are used in connection with these latter plants for starting the engine. When a light is turned on, or 
current is drawn for any purpose, an automatic switch turns the dynamo into a motor, and it starts the engine by 
means of the current stored in the battery. Instantly the engine has come up to speed, the motor becomes a 
dynamo again and begins to deliver current. When the last light is turned off, the engine stops automatically.

Since the installation of a direct-connected standard voltage plant of this type is similar in every respect, except as 
to motive power, to the hydro-electric plant, its cost, with this single exception, is the same. The same lamps, wire, 
and devices are used.

With gasoline power, the cost of the engine offsets the cost of the water wheel. The engine is more expensive than 
the ordinary gasoline engine; but even this item of cost is offset by the cost of labor and materials used in installing 
a water wheel.

The expense of maintenance is limited to gasoline and oil. Depreciation enters in both cases; and though it may be
more rapid with a gasoline engine than a water wheel, that item will not be considered here. The cost of lubricating 
oil is inconsiderable. It will require, when operated at from one-half load to full load, approximately one pint of 
gasoline to each horsepower hour. When operated at less than half-load, its efficiency lowers. Thus, for a 
quarter-load, an average engine of this type may require three pints of gasoline for each horsepower hour. For this
reason it is well, in installing such a plant, to have it of such size that it will be operating on at least three-fourths 
load under normal draft of current. Norman H. Schneider, in his book "Low Voltage Electric Lighting," gives the 
following table of proportions between the engine and dynamo:

This table is figured for an efficiency of only 40 per cent for the smaller generators, and 60 per cent for the larger. 
In machines from 5 to 25 kilowatts, the efficiency will run considerably higher.

To determine the expense of operating a one-kilowatt gasoline generator set of this type, as to gasoline 
consumption, we can assume at full load that the gasoline engine is delivering 2½ horsepower, and consuming, let 
us say, 1¼ pint of gasoline for each horsepower hour (to make allowance for lower efficiency in small engines). 
That would be 3.125 pints of gasoline per hour. Allowing a ten per cent loss of current in wiring, we have 900 watts 
of electricity to use, for this expenditure of gasoline. This would light 900 ÷ 25 = 36 lamps of 25 watts each, a liberal
allowance for house and barn, and permitting the use of small cooking devices and other conveniences when part 
of the lights were not in use. With gasoline selling at 12 cents a gallon, the use of this plant for an hour at full 
capacity would cost $0.047. Your city cousin pays 9 cents for the same current on a basis of 10 cents per 
kilowatt-hour; and in smaller towns where the rate is 15 cents, he would pay 13½ cents.

Running this plant at only half-load—that is, using only 18 lights, or their equivalent—would reduce the price to 
about 3 cents an hour—since the efficiency decreases with smaller load. It is customary to figure an average of 3½ 
hours a day throughout the year, for all lights. On this basis the cost of gasoline for this one-kilowatt plant would 
be 16½ cents a day for full load, and approximately 10½ cents a day for half-load. This is extremely favorable, as 
compared with the cost of electric current in our cities and towns, at the commercial rate, especially when one 
considers that light and power are to be had at any place or at any time on the farm simply by starting the engine. 
A smaller plant, operating at less cost for fuel, would furnish ample light for most farms; but it is well to remember in 
this connection plants smaller than one kilowatt are practical for light only, since electric irons, toasters, etc., draw 
from 400 to 660 watts each. Obviously a plant of 300 watts capacity would not permit the use of these instruments, 
although it would furnish 10 or 12 lamps of 25 watts each.

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

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