On Fri, 12 Oct 2012 08:59:25 -0400, "Existential Angst"
wrote:

Awl --

Would seem like a no-brainer, but goddamm, it shore has me beat!

Yeah, I know, pull the fuse!! Yeah, I know, the fuse labeled
"alternator".....

But when I did that, the alternator light or battery lite would not come on.
AND, iirc, I DID check the voltage at the battery, to see if it went down
to 12, or was up at the ususal 13-14, and indeed, it stayed at 13-14,
indicating a working alternator.

And the engine compartment is so g-d crowded/complicated, I can hardly tell
a wire from a hydraulic line, so it's not easy to even find the right wire.
I figger at 100 A, the wire would have to be perty thick....

The reason for disconnecting the alternator is this:
On an old mazda 929S, the alternator went -- and I could StoG that my mpg
jumped by 15%.... would like to re-examine this phenom with my ScanGauge,
to see if it is real.

If this is indeed a true phenom, I could wangle myself a bit of a hybrid by
just keeping a spare batt in the car, and switch in the alternator when the
first batt dies. But basically try to do all the batt. charging at home.

Altho, there proly is no free lunch: I'll proly use my gas savings to buy a
new battery every year?? LOL
But the actual tradeoff would be inneresting to see.

You may have only a single connection to the alternator which goes
straight to the battery of to the battery via a connection on the
starter. The reason is that the internal alternator regulator receives
power from the battery via the main power cable.

If this is the case then in order to externally control the alternator
you would need to cut into the regulator and jury rig some sort of
external connection which would likely end up in bypassing the
regulator.

This certainly is possible - I have done it with two alternators for
marine use in order to use external regulators, however whether it is
logical for an automobile can be argued.

If you have, say a 100 amp alternator, then: 100 amps x 14 volts =
1,400 watts = 1.8 Hp. But the alternator is driven at a higher speed
then the crankshaft so there is additional H.P loss due to the
over-driving plus belt friction. For guessing purposes say 100%
losses so Required H.P. then is 3.6 HP.

You then need to estimate the average amount of H.P. required by your
driving style and compute required alternator power as a percentage.

Back in my days of unofficial, Sunday afternoon, drag racing it was
common knowledge that disconnecting the alternator (and the fan) would
result in a faster car.
--
Cheers,
John B.