From: Rob F. [Huntnphool@aol.com]
Sent: Monday, July 15, 2002 10:34 PM
To: 928
Subject: [928] Those of you with charging problems......LONG!!!!

I originally posted this on our local Pac. NW site but it seems that many
of you are having similar problems. FWIW, this may help you understand a
bit. Oh and by the way, I am one of those installers that some of you feel
so compelled to put down all the time. (You know who you are)To you I
would say, don't even bother reading this as you are already blinded by
your stereotyping. For the rest, I hope this helps you understand a
little.It seems that everyone that owns a Porsche has a battery problem at
one time or another, so I while I had the opportunity to see the under
side I jumped on it. It would help if you understood ohms law but for the
others that may be reading this that dont, I will try and keep it simple.

Direct current, or DC, is defined as a flow of electrons which travels in
one direction only and is what supplies the power to the electronic
components. Voltage is the electrical pressure that moves charged
particles in a circuit. Current is the rate of electron flow through a
given point, and Resistance describes the electrical conductivity that
various materials posses. Low conductivity materials resist the flow of
electricity. The resistance of a wire is determined by the wires
conductivity, diameter, and its length. Ohms law is the electrical formula
that defines the relationship of these elements to each other.

Our cars draw a considerable amount of current to start them, and power
all the electrical components once its started. From my understanding,
there are two different size alternators for our cars, and I'm not sure
what the output is for either. The alternator takes over the electrical
power of the car once its running. It also needs to charge your battery
back up after initial cranking. The problem with this is our batteries are
in the rear of the car, and we have an adequate gauge wire at best between
the starter and the battery.

Now lets assume for a second that its raining in Seattle (Boy thats a
stretch) and your sitting at a stop light, foot on the brake, radio
playing the Mariner game, wipers wiping, fan blowing on the fogged window,
headlights and running lights on, and the turn signal blinking. With all
these components being used at once, we are probably seeing a draw of 85
amps or more. This doesnt leave much current to do anything else let alone
charge your battery. One of the ways to help this problem is to increase
the diameter of the wire allowing current or electrons to flow more
freely.

Suppose you have a tank of water. At the bottom of the tank there is a
valve that leads to a pipe. Tank, Valve, Pipe.
When the valve is opened , pressue forces the water through the pipe.
Voltage is like that pressure, only its electrical pressure that is
forcing charged particles through the cars circuits. If you open the valve
wider, more water flows through the pipe. If you make the valve opening
smaller, less water flows through the pipe. This increase and decrease in
the rate of water flow is comparable to current, only current is the rate
of electrons flowing through a conductor.

If you were to decrease the size of the pipe or say bend it slightly, the
rate of water flow would decrease because you would be increasing the
resistance. This limitation in flow volume is similar to the electrical
resistance, which resists the flow of electrons.

We can also increase the current going to the battery by changing the type
of wire used. Aluminum doesn't flow electrons as well as copper. Similar
to trying to flow water through a pipe, or oil through the same pipe.

I hoped this helped you out a bit. If you have any more questions give me
a yell. I'm sure the others have opinions on all this as well. You may
check with them too before you make a decision.

Rob Fossett
85S Auto
Prussian Blue Metallic