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This is an attempt to work out Battery 101 and the
differences in positive and negative ground systems. Let's define terms
first. The major problem in defining terms is each term may have multiple
meanings.
Ground - This term refers to the electrical potential of
the earth, dirt, or ground. Ground also refers to the reference point that
current flows to.
Circuit - A simple circuit is the path from the source of
electrical current, through a load, and returning to the current source i.e. a
battery is connected to a light bulb where the current flows out of the battery,
through the light bulb and returns to the battery.
Current - Current is the flow of electrical energy.
There are two ways of describing current. One is electron flow and the
other is hole flow. Electrical current does not cause molecules to
move. The copper molecules do not move in the wire. The current
moves through the molecules.
Electron flow is the theory where a molecule becomes
excited by an increase in energy which causes an electron (-) to break
free. This electron collides with a neighboring molecule imparting it's
excess energy to the new molecule which causes another electron to become
excited and leave. This process is propagated over and over resulting in
current flowing from one electron to another. The current flows from
negative towards positive.
Conventional current flow or hole flow is a theory where when a molecule
gives up an electron, it becomes positive which attracts negative charges.
This attraction of negative charges pulls an electron from a neighboring
molecule leaving that neighbor positive and itself becoming neutral again.
This positive charge or hole then propagates from positive towards
negative.
Confusing??? You bet. The essence is to determine which
direction the energy, or power, flows. The Einstein's are not sure, so
everyone uses both theories and flip-flops whenever each theory fits
best.
These
theories apply to automobile wiring thusly: If current flows towards the
positive charge, then, the positive terminal of the battery is the ground
reference, hence positive ground. If current flows towards the negative
charge, then, the negative terminal is the ground reference, hence negative
ground. An electrical circuit (lights, horns, flashers, etc) does not care
which direction the current flows as long as there is a wire from the current
source, traveling through the load, and returning to the
battery.
Polarity is critical to some devices on an automobile such as the
following cases:
1. Starting Motor - if the polarity of the motor is switched, the
starting motor will turn in the wrong direction.
2. The generator (alternator) must drive current in the reverse
direction through the battery in order to dissolve the acid salts from the
battery plates. These salts act as an insulator restricting current flow
or "dead battery".
3. Ammeter (Amp Gage) - this is a galvanometer which shows the
direction and magnitude of current through the battery. If it swings to
the left then current is coming out of the battery and if this continues long
enough the battery will become dead. If this gage swings to the right,
then current is flowing into the battery, charging it. If this gage is
centered then current is neither flowing into or out of the battery, meaning the
battery is fully charged.
As has
been stated many times already, regardless of the ground reference in a car,
charge the battery by placing the red (+) lead on the "+" terminal and the black
(-) lead on the "-" battery terminal in order to drive the proper reverse
current through the battery to remove the acid salt deposits (current resistors)
from the battery plates thereby restoring the battery to full current potential
(fully charged).
This
is a long reply. Congratulations if you made it this
far.
I used to think I understood
batteries and charging systems but never gave much thought to a positive ground
system and I am having trouble getting my small brain around it. Normally
you think in terms of hitting the positive with a wrench and drawing a spark or
welding the wrench to the fender. Here I am actually bolting the positive
side down to the block. I used to think that in charging a battery you
were changing some stuff around on the plates that flowed positive to
negative. But, when I have a positive ground batter, appears the generator
is creating deposits in the opposite direction since the generator connection is
coming from the ground side. Then, I have to square that with putting it
on a battery charger with the positive to positive and negative to negative
which would seem to be the opposite of how the battery lives in the
car.
Can someone square me away on
this?
Tom
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