On Fri, 6 May 2011 11:47:56 -0400, "Wilbur Hubbard"
wrote:

"Stephen Trapani" wrote in message
...
On 5/5/2011 12:44 PM, Stephen Trapani wrote:
On 5/5/2011 10:43 AM, Wayne B wrote:
On Thu, 05 May 2011 10:02:55 -0700, Stephen Trapani
wrote:

I think Larry once explained why the amps get cut in half, but I
forgot.
I have an amp meter installed in line between the alternator and the
battery switch. Last weekend I had a borrowed Fluke clamp meter. When I
put the clamp on the line coming out of the alternator it read exactly
half of what the in line amp meter was reading. Why is that?


Sounds to me like an inaccuracy in one of the meters. Do I
understand correctly that you are clamping the Fluke around the one
and only wire delivering power from the alternator?

Yes.

Do you have the
Fluke switched to DC amps, and on the correct scale?

Yes. I'll ask the guy who loaned me the Fluke to be sure.

I called Fluke. The setting I used was supposed to give me straight DC
current. So...mystery NOT solved. Where's that damned Larry when you need
him???

Stephen



An alternator puts out Alternating Current which runs through a bridge
rectifier which rearranges it to pulsed Direct Current. Pulsed DC is not
real DC. That meter will only read right on loads from the battery. Try it
on a lead from the battery to the load and I bet it then reads correctly.

Larry wasn't as smart as me. . .

Wilbur Hubbard


Ahhh Willie-boy. Do you sit up nights studying or are you naturally
this stupid?

DC electricity is a form of electricity where the electrons all move
in the same direction ( from an area of negative (-) charges to an
area of positive (+) charges).

AC electricity is a form of electricity in which the polarity reverses
and therefore electrons flow one way during half the cycle and the
other way during the other half.

Pulsed DC is simply a DC current that is switched on and off (pulsed)
it IS NOT A NEW FORM OF ELECTRICITY.

An alternator produces AC electricity and an automotive type
"alternator" produces DC electricity by converting or rectifying the
AC current into DC current. It does this by using "diodes" which are a
little two legged gizzy that can be thought of as one way electrical
valves. Connected one way they conduct only during the positive
portion of the AC wave and if connected "backward" they conduct during
the negative portion.

A bridge rectifier is simply 4 diodes with two connected to conduct
during the positive portion of each side of the alternating wave form
and two conducting during the negative. This gives the smoothest DC
form possible in a simple DC circuit from an auto type alternator.

Now, if you connect the positive lead of your meter to the alternator
output connection and the negative lead to ground you will read the
output voltage of the alternator, not some idiotic and fictitious
Pulsed DC that Willie-boy talks about.

Why? Because while the DC current is actually fluctuating it is doing
so fast that you meter can't react quickly enough and so reports the
correct effective voltage. Most DC stuff doesn't care what it gets as
long as it all comes from the same direction.

When the pulsed (so fast you can't measure it with your meter) DC
reaches the battery it charges it just as though it was pure, filtered
DC.

So. If you are interested in a DC circuit stick your meter on it and
read the voltage, don't get all wound up in pulsed DC and all the
other weird things that Willy-boy comes up with.

Amps and volts:
Power is measured in Watts which are the amperage used in the circuit
times the voltage in the circuit. If you have a 12 volt light bulb and
it draws 2 amp then you have a (121 x 2) 24 watt light. Change the
amperage or the voltage and the power (Watts) change.

12 Volts X 4 amps = 48 watts
1 V X 4 A = 4 watts.
1000 V X 0.048 A = 48 watts.
and so on.
Cheers,

Bruce
(bruceinbangkokatgmaildotcom)