Civic alternator shut off, the easy way

[California98Civic]

Wow is this thorough! Thanks very much for offering a more solid sense of the types of gains to be had from these "smart alternator" switching mechanisms. BTW, to answer your question, I am the ecomodder you referred to here:

Originally Posted by steffen707

4. Another ecomodder (sorry don't remember who, please let me know and i'll edit) told me that he found out that if you disconnect the "IG" and the "L" wire this disables the alternator. He thought that the "L" circuit was providing enough power to energize the field windings. Well he was right. I tested this by starting the car with both "IG" and "L" disconnected and it operated just like test 1. I also tried starting the car with just "IG" disconnected, removed jumper cables, the car ran fine, then disconnected "L" on the fly, the car imediately starting running super rough like test 1.

That's my set up; we discussed it in PM and on thread. If you link to my cut-off switch build, which describes how to do this, I'd appreciate it. But it is not important.

Thanks!

[steffen707]

No problem man, I updated it to give you credit and linked to your thread. Much thanks as its basically the key to doing this right.

[steffen707]

Just in case people wanted to know if this gain is worth the hassle, read below.

If you normally get 50mpg, and gain 10%, that's a 5mpg gain.
10,000 miles @ 50mpg cost you 200 gallons of gas at $4 per gallon that's $800
10,000 miles @ 55mpg costs you 181 gallons of gas at $4 per gallon is $727
a savings of $73 per 10,000 miles or $7.30 per 1,000 miles

This doesn't account for the charging cost on the grid either.
For my short term testing it cost me $0.03 per day to charge my battery, but i have a very small 10 mile daily commute. 5 miles each way.

So if you do drive 20,000 miles and can get 5 years out of the battery pack you
would save $730 less the charging cost. Hopefully your new batteries, copper cable, switches ect. cost less than this. Most guys that try this have a free supply or cheap supply of deep cycle batteries.

This doesn't take into account the benefit of bragging to friends, saving the earth
or enjoying ecomodding as a hobby. Also if one were thinking about buying
a new car to get better gas mileage this option may be worth it. Or if your MPG is already low this mod will pay for itself more easily.

Take a 10mpg vehicle that uses 1000 gallons over 10,000 miles. That's $4000 in gas, with a 1mpg boost you save 91 gallons, or $364 dollars.

Although, if you're getting 10mpg you should really find a better gas mileage vehicle.

[steffen707]

Originally Posted by California98Civic

Wow is this thorough! Thanks very much for offering a more solid sense of the types of gains to be had from these "smart alternator" switching mechanisms. BTW, to answer your question, I am the ecomodder you referred to here:



That's my set up; we discussed it in PM and on thread. If you link to my cut-off switch build, which describes how to do this, I'd appreciate it. But it is not important.

Thanks!

This was an interesting read, "If you have an alternator and are using the factory style indicator light on your dashboard, it is a pretty helpful thing. It helps kick-start the alternator into working at idle speeds when you first start the car"

and "One is that you have to to rev the engine up to approx 1100rpm once after the engine is first started for the alternator to begin charging - the alternator has to reach a high enough RPM so that it "self-excites"."

this is what I viewed, but mine was about 2000rpm i believe before it self excited.

source, Alternator and Generator Theory

[greasemonkee]

I did this mod myself today and used the AC switch (modified and connected to ground) in my VX converted CX.

The Fluke meter reads a max of 14.31 V. with alt in max charging mode and 12.65 V. in low charge mode. These figures hold very steady with rpm change regardless of load.


Something no one has mentioned is that this 1.66 volt reduction equates to less energy required to operate all of the load sources. So for example if the total electrical load of the vehicle is a 10 amp load at 14.31 volts you have 143.1 watts the alternator must produce, and then you drop the voltage to 12.65 volts you have 126.5 watts (approximately) the alternator must produce to keep the system/battery balanced. So to save 16.5 watts of power is it worth it? If it's free I suppose.

The underdrive pulley idea may have merit if one can be picked up cheap, the turbulence within an alternator along with a continuously bending belt might be quite parasitic.

[wagonef8]

AEM Tru-Power UNDER DRIVE PULLEY KIT HONDA CIVIC SI CRX 88 23-7012C WITH MITSU | eBay

I got my pulley with alternator for $20 on a local forum