battery, as the
generator will furnish the current for the lamps, and also send a
charge into the battery. If the lamps are not used, the entire
generator output is utilized to charge the battery, unless some
current is furnished to the ignition system. Overcharge is quite
possible.

When the engine is not running, the lamps are the only load on the
battery, and there is no charging current. Various drivers have
various driving conditions. Some use their starters frequently, and
make only short runs. Their batteries run down. Other men use the
starter very seldom, and take long tours. Their batteries will be
overcharged. The best thing that can be done is to set the generator
for an output that will keep the battery charged under average
conditions.

From the results of actual tests, it may be said that modem lead-acid
batteries are not injured in any way by the high discharge rate used
when a starting motor cranks the engine. It is the rapidity with which
fresh acid takes the place of that used in the pores of the active
materials that affects the capacity of a battery at high rates, and
not only limitation in the plates themselves. Low rates of discharge
should, in fact, be avoided more than the high rates. Battery capacity
is affected by discharge rates, only when the discharge is continuous,
and the reduction in capacity caused by the high rates of continuous
discharge does not occur if the discharge is an intermittent one, such
as is actually the case in automobile work. The tendency now is to
design batteries to give their rated capacity in very short discharge
periods. If conditions should demand it, these batteries would be sold
to give their rated capacity while operating intermittently at a rate
which would completely discharge them in three or four minutes. The
only change necessary for such high rates of discharge is to provide
extra heavy terminals to carry the heavy current.

The present standard method of rating starting and lighting batteries,
as recommended by the Society of Automotive Engineers, is as follows:

"Batteries for combined lighting and starting service shall have two
ratings. The first shall indicate the lighting ability, and shall be
the capacity in ampere hours of the battery when discharged
continuously at the 5 hour rate to a final voltage of not less than
1.7 per cell, the temperature of the battery beginning such discharge
being 80 deg.F. The second rating shall indicate the sta