, each charging
line will require 10 times 40, or 400 watts. The size of the generator
will depend on the number of charging lines desired. With 10 amperes
charging current per line, the capacity of the generator required will
be equal to 400 watts multiplied by the number of charging lines. One
charging line will need a 400 watt outfit. For two charging lines 800
watts are required. Each charging line is generally provided with a
separate rheostat so that its charging rate may be adjusted to any
desired value. This is an important feature, as it is wrong to charge
all batteries at the same rate, and with separate rheostats the
current on each line may be adjusted to the correct value for the
batteries connected to that line. Any number of batteries up to the
maximum may be charged on each line.

[Fig. 46 Thirty-two battery motor-generator charging set]

In choosing a charging outfit, it is important not to get one which is
too large, as the outfit will operate at a loss when running under a
minimum load. It is equally important not to get one which is too
small, as it will not be able to take care of the batteries fast
enough, and there will be a "waiting list" of batteries which cannot
be charged until others are taken off charge. This will prevent the
giving of good service. Buy an outfit that will care for your needs in
the future, and also operate economically at the present time. Most
men going into the battery business make the mistake of
underestimating their needs, and getting equipment which must soon be
discarded because of lack of capacity.

The manufacturers each make a number of sizes, and the one which will
best fill the requirements should be chosen. In selecting an outfit
the manufacturer's distributor or dealer should be consulted in
deciding what size outfit to obtain. The particular outfit will depend
on the voltage and frequency of the alternating current power
circuits, the maximum charging current desired (10 amperes per line is
ample), and the greatest number of batteries to be charged at one time.

For the beginner, a 500 watt ten battery outfit, as shown in Fig. 45,
is suitable. For the medium sized garage that specializes in battery
charging, or for the small battery service station, a one kilowatt
outfit is most satisfactory. Two charging panels are generally
furnished with this outfit, and two charging lines may thus be used.
This is an important feature, as one line may be used in sta