The Washington times., 1917-02-03
STORAGE BATTERY
TEST IS EXPLAINED
Use of Pocket Ammeter for
Purpose Will Cause Consider
able Damage.

I can test dry cells with a pocket
ammeter. Why can't I test my stor-
age battery the same way?"
This question is frequently asked by
automobile owners, many Of whom have
learned through bitter experience that
there must be a reason why the familiar
little pocket ammeter. used to tell
whether dry cells are weak or strong.
will cause considerable damage to a
storage battery.
To the average automobile owner a
battery is a good deal like Greek puz-
zle. 1t is hard for him to appreciate
that a storage battery is a purely chem
ical device. And so, a battery Is a bat
terry. But there is a big difference be-
tween the chemical and electrical ma
lures Of the dry cell and the storage
battery.
Operation Explained.
Both dry and storage batteries operate
by chemical action when the circuit is
closed" The dry cell, when II Is ex-
hausted, is done; the storage battery,
when exhausted, cap be recharged. The
ordinary dry cell has a comparatively
mits only a certain amount Of electricity
to be discharged at one time. But just
the opposite is true Of the storage bat
tery-its internal resistance" Is very
low, and II can discharge a tremendous
amount OF current when given an op-
portunity.
When the pocket ammeter Is used
on a dry cell, the amount of current
liberated is smalli doesn't fnjure the
dry cell and doesn't injure the am
meter. But the same little instru-
ment, placed on a cell of a storage
battery, will in most cases be burnt
up by the tremendous current dis
charged, and at the same time the
storage battery cell is permitted to
discharge itself all at once, with a
ruinous result upon the battery itself.
The same thing occurs when tools or
other metal objects are carelessly
placed on top OF the battery.
when Test IL HarmfuI.
A dry cell can be tested when 1t Is
idle, but the same sort OF test on a
storage battery is not only harmful
IL unskillfully done, but doesn't tell
anything even to an expert Volt
meter and ammeter readings should
uCNCE OC dNlClnpNco hulCSo lnC OdIlCEg
is either being charged or discharged
at the time, and then only by an ex-
pert. Tests with a hydrometer can
be, and should be, frequently made,
and no harm can result: but any
ether sort of test should be given by
some one who has the proper instru.
ments and knows how to connect
them up correctly.
quite frequently we are asked to
tell what is the trouble with a bat
terry which the owner has tested with
pocket ammeter," says r. l. Some
local distributor for Prestolite bat
teries. The little scratches on the
battery terminals where an ammeter
has been placed tell a story OF bat
terry abuse which the average own
er finds trouble in understanding.
Battery May Be Ruined.
"All he did was to test it, and the
battery may be completely ruined
You see, we have a selfish reason for
giving free service to battery owners,
1t is much simpler for US to test a
battery properly than II is to make
repairs after the owner has tested II
improperly. Besides, it's much better
for the owner.
The service is free. and we are
glad to extend it to all automobile
owners. The user might as well face
the fact. that you can't tell from
looking at battery whether 1t is in
good shape or not. The only way Is
to have 1t tested systematically-at
least, once every two weeks. and
, oftener in hot weather. In that way
| the little troubles can be caught be-
fore they become big ones.
alNa haVa hQftaTV hare
! for the sole purpose Of giving this
free service, and the automobile
! owner should not feel at all back
ward about taking advantage of 1t
we feel that 1t is just as much tC
| our infarast q IL La In hIa %