[C3H8]

nice topic here.
I have an alternator delete switch as well as a few other power related things.

Some of you who are measuring fuel usage with and without the alternator should keep in mind that the fuel pump will operate at lower speed when alternator-less, this means the possibility of a bit less fuel pressure. The fuel pressure may or may not drop depending on you're car's fuel system design.

My car is set up for quite a bit higher fuel pressure when it was originally designed for. Stock, it is suppose to be 45psi. I doubled that to 90psi by modifying the pressure regulator. I also installed smaller injectors to compensate for the increased fuel flow. The end result is the short and long term fuel trim's are close to zero with the modified system. As a consequence of this high pressure my fuel pump is probably pushing its limit on fuel pressure. When I turn the alternator off, I go from a bit over 15 volts to about 13 volts and over time it slowly drops down from 13 volts. I never figured out why disabling the alternator sowed a slight drop in mpg until one day I checked the fuel pressure and saw it dropped about 7 psi when I switched the alternator off. This now makes sense because my obd2 scanner shows a corresponding increase in short term fuel trim when I kill the alternator. I believe the drop in fuel pressure is made up for by slightly increasing the injector duty cycle. The net result is the same amount of fuel delivered to the engine, but my MPG gauge shows a slight drop in fuel economy with the alternator off. Since the computer calculated mpg by reading injector duty cycle, among other things, this is not surprising. the MPG gauge's computer THINKS I am using more fuel although I am not. I think the drop in the fuel economy gauge is a fake drop.

In reality when I fill up the tank and calculator my mpg by miles driven vs fuel used, it always comes out to a few increased mpg's when I disable the alternator as much as possible. Which is contrary to what my mpg gauge says... This is a fluke in the MPG gauge and mpg computer system for my car because of my fuel pump being pushed to it's limit.

I now realise that if i upgrade to a bit larger fuel pump that can more antiquity handle the high fuel pressure I am trying to run, my fuel pressure should remain the same with the alternator on, or off. And as a result my mpg gauge should start showing an increase in fuel economy when I turn the alternator off.
Some of you guys should keep this in mind because you might be calculating fuel economy by a means other then miles driven vs gallons filled at the pump. You're fuel economies could be erroneously off by more then a few percent.

As far as ampere's go. My car seems to draw twice the amount or more then most of you, even if i set my alternator voltage back down to stock. I wonder why that is. Maybe because it's a full size car and has more electrical stuff, such as everything that can be electric, is.

With the exception of my head light bulbs, brake light bulbs, and turn signal bulbs, every single other light on my car is LED based. I hand made the led conversion my self. I did not figure the headlight, brake light and turn signal bulbs are worth converting to led because it is time consuming and the brake and turn signal bulbs are only ever temporarily on. They are never predominantly on for more when 20 seconds or so, so any gains to be had by converting them are truly insignificant at best. Time consuming and pointless at the worst. I would convert the headlight's to led but I do not have the paitence to glue and solder a few hundred led's into each headlight housing. Plus the cost of that...

I might make a how to guide on diy led conversion on the cheap for you guys, one day.

All figures @ 15.5v

Brake lights: 47 watts
Running lights for all 4 corners: 6 watts (1.5 watts per corner!!)
Low beams: 131 watts
High beams: 142 watts
Ign On eng OFF: 75 watts
Eng ON: 190 watts
1 Fuel injector: 14 watts
O2 sensor heater: 12 watts
Fuel pump: 46 watts
Sub-woofer & amp @ full loudness: eight hundred fifty watts!!!
Head unit @ full loudness: 57 watts
(keep in mind the head unit and sub wattage is directly dependent on volume. At low what most would consider normal volumes my head unit takes about 20 watts, and the sub+amp takes about 100 watts, it's only when I crank them up that the watts consumed goes through the roof, and my headlights dim considerably even with my alternator set to 15.5V. To save battery power I don't even have the amp+sub powered on when I have the alternator disabled.) Same holds true for the a/c

Air conditioning watts: you don't want to know :/

I used a 10 amp shunt type amp meter for 9 amp or lower loads.
90 amp shunt type amp meter for 10 amp to 80ish-amp loads.
200 amp shunt bla bla for bla bla

I didnt bother with testing the starter. I do not EOC because its difficult with a manumatic and i tend to leave the engine running ruring red lights, fuel refills, quick run ins to a store (less then 1 minute). I know this hurts gas mileage, but I would personally rather sacrifice a few miles per gallon compared to the greatly increased wear that you EOC people are expierencing on you're starters AND the flywheels or flex plates. Anyone ever change out a flywheel or flex plate? Even if I completely disregard the cost of a starter and a flywheel or flex plate, lets say the replacment is free so the only thing you have to spend is time changing them. ITs a major P.I.T.A to change those items out and not worth the few mpg's to me. ymmv.. good luck and my hat off to those of you who EOC. I just can't bring myself to do that to my car.
I have been messing with injector off decelerating to stop signs, lights, etc, keeping the engine spinning, though.