Rabbit-like, the Cummings car bounded
over the bumpy railroad crossing.
Then - blump! A hollow
thud resounded above the rattles, Harry Cummings jammed on his brakes.
His wife shrieked.
"What have you done now?"
she demanded.
"Aw, say!" protested Harry.
"What's the idea of blaming me for everything?
Can I help it if we hit a loose stone and it bounces up against the
floor boards?"
"Well, you could be more careful,"
snapped Mrs. Cummings.
She sniffed once or twice.
"Say what you like," she insisted, "you did do something to this car!
Can't you smell it burning?"
"Gosh, I guess you're right!" exclaimed
Harry. He steered the car over
to the side of the road and stopped.
"Smells like battery acid to me," he muttered after a moment.
Quickly he lifted the front seat and raised the cover to the storage
battery compartment.
Some minutes later, Gus Wilson and Joe
Clark, the owners of the Model Garage were listening to Harry Cummings
strange tale of woe.
"Look at that, will you," Harry directed,
pointing down at his uncovered battery.
"The compound on top of that left cell is split right across the
middle where the filler cap goes.
When I first looked at it, the filler cap had entirely disappeared
and the top of the cell was bulged up like a broken stick where that crack
is.
"I hunted around and finally located the
missing cap at the bottom of the battery compartment.
I pushed the top of the cell back in place, screwed in the filler
cap, and then drove here."
Gus Wilson leaned over to inspect the
battery, Joe Clark peering inquisitively over his shoulder, while Mrs.
Cummings fidgeted impatiently in the back seat.
"Joe suppose you take my car and drive
Mrs. Cummings home," Gus suggested after glancing at the back seat and
recognizing the warnings of an impending verbal storm.
"There's no need for you to wait around until we've found the
trouble, Mrs. Cummings."
When they were gone, Gus busied himself
with the leads from the battery.
The battery compartment was metal and the heavy cables that led from the
battery passed through holes in the metal sides.
As Gus pulled and jiggled the cable
leading to the starting motor, long yellow sparks zigzagged in all
directions.
"Here's your trouble," Gus announced
triumphantly. "The insulation on this cable has worn through right where it
leaves the battery compartment.
Every time you went over a bump, the bare wire came in contact with
the metal sides of the compartment and caused a short circuit."
"That's a short circuit all right,"
Cummings agreed, "and a bad one too.
But what split the top of the battery open?"
Gus scratched his head.
"Well, you can bet your hat the short circuit had something to do
with it" he decided at last. "My
guess is that you've been doing a lot of daytime driving.
That charged up your battery and it began to gas.
By that I mean that it bubbled off hydrogen gas.
"Hydrogen is an explosive gas when it's
mixed with air and your battery
compartment, being closed over, confined the gas that was given off.
When you went over those bumps at the railroad crossing, the bare
wire on that worn battery lead came in contact with the metal sides of the
compartment and caused a short circuit.
"The sparks from the short ignited the
gas mixture and blew the top off that left hand cell.
The thud you heard was the rubber filer cap hitting the cover on the
battery compartment. You should
inspect your battery leads now and then," he finished.
"Isn't there some way you can reduce the
charging rate of the generator when you're going on a long trip," Harry
asked, after instructing Gus to put in a rental battery and a new set of
battery cables.
"Sure, you can reduce the charging rate
in most cases," Gus agreed. "But
the easiest way is to burn your lights when you go on a long drive.
The additional drain will prevent over charging."
"But I though every car generator had a
cut-out that switched the generator out of the circuit when the battery was
charged," Cummings objected.
"Generators have cut-outs, but they don't
work that way," replied Gus, "Cut-outs are automatic switches that cut the
generator out of the circuit when the car is running so slowly that the
generated voltage is less than the battery voltage.
On most cars, the generator begins charging at twelve miles an hour
and decreases at twenty-five miles an hour."
"Well how can a punk mechanic like me
tell when his electrical system is working as it should?"
Harry inquired as he watched Gus lift the rental battery into place.
"If most of the drivers in the world are as dumb as I am, they never
think twice about the battery, much less the generator."
"That's that way with most car owners," Gus chuckled.
"It's a case of out of sight, out of mind.
"It's a cinch to check upon your
generator. All you've got to do
is make use of that ammeter on your dashboard.
With the motor off and your lights on, jot down the reading of the
ammeter. Of course, it will show
on the discharge side of the dial.
"Then with your car running at fifteen
miles an hour and your lights off, take a second reading.
This should show on the charge side of the meter.
When you compare both readings, the second one should be a little
more than the first. Most
generators are adjusted to give their greatest output of fifteen or twenty
miles an hour so by making the test at that speed you get the greatest
value."
"Sounds easy enough," Harry agreed, "but
what I want to know is how I could have located that short before anything
happened."
"Well, in the first place," explained
Gus, "you ought to take better care of your battery. A battery coming from
the manufacturer is as perfect as it can be made and if it gives up before
its usual span of life you can charge it up to neglect on your part.
"A battery is just like a human being.
If it doesn't get enough food, it gets weak; and if it get too much,
it gets sick. Most battery
troubles can be traced to neglect - lack of water, undercharging, or
overcharging."
By this time, Joe Clark had returned and
was helping Gus connect the new battery cables.
"The best way to take care of a battery,"
Gus continued as he took the wrench Joe handed him and tightened one of the
battery terminals, "is to do it periodically.
Test your battery every two weeks with a hydrometer.
In order to make it a habit, do it on the first and fifteenth of
every month. If a cell reads
much below 1,250 on two successive testing dates, get the battery tested at
a service station.
"Always test all the cells to make sure
each one is healthy, and most important of all, don't ad anything but
distilled water."
"But, Gus," Cummings interrupted, "the
solution in a battery is made up of water and acid, isn't it?
How come you don't have to add some acid now and then?"
"If the battery is in good condition,"
Gus replied, "the only reason for losing any solution is evaporation, and
the acid doesn't evaporate. All
you've got to do is replace the distilled water to keep the solution at the
proper strength. Of course, if
you lose some of the solution through a leak, you'll have to add acid and
water accordingly.
"Speaking of leaks," continued Gus, "any
leaks in your electrical system will drain your battery too and make it
weak. So besides testing the
battery periodically you should test your wiring as well."
"Isn't there some quick way to test the
whole system for short circuits?"
Harry asked.
"There is, and it's almost as simple as
checking the air in your tires," said Gus as he reached for a file.
"Joe and I can show you how in a jiffy."
The two garage men busied themselves with the headlights and
cowl lamps as Harry Cummings looked on.
"The first step is to turn on all your
lamps and remove the bulbs," explained Gus as he worked.
"Then disconnect one of the battery cables and hold one end of a
coarse file against the free terminal post on the battery, like this.
Next, rub the unconnected cable end along the file.
If sparks are noticed there's a ground in the wiring.
From the looks of this," Gus said indicating the absence of sparks on
the surface of the file he was holding in his left hand, "I'd say that those
new battery cables fixed up the only short you had.
You know, every short won't be as easy to find as the one that caused
your trouble, but nine-tenths of the shorts, that are found in cars, are
caused by worn-out battery cables.
"And there's one more thing," Gus added.
"If you do much driving in real cold weather always start the motor before
adding the distilled water.
"Water floats on acid, you know.
So if you pour it in and let it stand, it may freeze.
Running the motor fast enough to charge the battery, however makes
the solution circulate around.
Once the water has mixed with the acid there isn't much danger of freezing.
Of course, in very cold weather, it's sometimes wise to keep the
specific gravity of the solution up to 1.275."
"There's more to this battery business
than I suspected," Cummings confessed as he waited for Joe to slide back the
doors of the garage.
"Just remember one thing," Gus called.
"Your battery is probably all right when you buy it and you can keep
it that way for quite a few months if you'll only take moderately good care
of it."
END
