nced by the heat caused by the current passing
through the battery.

Age of Battery.

Another factor which should be considered in connection with capacity
is the age of the battery. New batteries often do not give their rated
capacity when received from the manufacturer. This is due to the
methods of making the plates. The "paste" plates, such as are used in
automobiles, are made by applying oxides of lead, mixed with a liquid,
which generally is dilute sulphuric acid, to the grids. These oxides
must be subjected to a charging current in order to produce the spongy
lead and lead peroxide. After the charge, they must be discharged, and
then again charged. This is necessary because not all of the oxides
are changed to active material on one charge, and repeated charges and
discharges are required to produce the maximum amount of active
materials. Some manufacturers do not charge and discharge a battery a
sufficient number of times before sending it out, and after a battery
is put into use, its capacity will increase for some time, because
more active material is produced during each charge.

Another factor which increases the capacity of a battery after it is
put into use is the tendency of the positive active material to become
more porous after the battery is put through the cycles of charge and
discharge. This results in an increase in capacity for a considerable
time after the battery is put into use.

When, a battery has been in use for some time, a considerable portion
of the active material will have fallen from the positive plates, and,
a decrease in capacity will result. Such a battery will charge faster
than a new one because the amount of sulphate which has formed when
the battery is discharged is less than in a newer battery. Hence, the
time required to reduce this sulphate will be less, and the battery
will "come up" faster on charge, although the specific gravity of the
electrolyte may not rise to 1.280.

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CHAPTER 8.
INTERNAL RESISTANCE.
--------------------

The resistance offered by a storage battery to the flow of a current
through it results in a loss of voltage, and in heating. Its value
should be as low as possible, and, in fact, it is almost negligible
even I in small batteries, seldom rising above 0.05 ohm. On charge, it
causes the charging voltage to be higher and on discharge causes a
loss of voltage. Fig. 26 sh