on/off switch for alternator? (Looking for directions / help / how-to)

[trdfreak03]

Hey everyone,

just wondering how i would go about adding an on/off switch to deactivate my alternator to achieve higher mpg! ... if anyone could send me in the right direction that would be great

i'm driving a 2003 toyota echo

thanks

[Daox]

I did this to my Paseo (which has the 1.5L engine that came just before yours). It works extremely well as long as you don't need to go on long trips. You'll also need a deep cycle battery to replace your normal starting battery. You can see my mod done here:

Daox's 1997 Paseo Build Thread - alternator disable switch

[trdfreak03]

Originally Posted by Daox

I did this to my Paseo (which has the 1.5L engine that came just before yours). It works extremely well as long as you don't need to go on long trips. You'll also need a deep cycle battery to replace your normal starting battery. You can see my mod done here:

Daox's 1997 Paseo Build Thread - alternator disable switch

easy stuff...

do you know where i'll find that "alternator field wire"... is it a tiny wire that runs of the alternator into the cabin?

[Daox]

My alternator has a connector with three smaller wires coming off of it. I unplugged each of them individually until I found the one that made the difference. It was noticeable. Unless you have a wiring diagram, thats the only way I know how to identify it.

[trdfreak03]

Originally Posted by Daox

My alternator has a connector with three smaller wires coming off of it. I unplugged each of them individually until I found the one that made the difference. It was noticeable. Unless you have a wiring diagram, thats the only way I know how to identify it.

Hey

ok .. i think i go it ... I saw the 3 wire plug off my alternator ... red/blu/yellow...

i'll mess around with it on the weekend.

thanks for your help!

[Daox]

Might even be the same alternator. Mine was the middle one, it was blue.

[myzter]

could you find the positive lead and connect a SPST toggle On-Off ?

[Piwoslaw]

Connecting and disconnecting the positive lead on a working alternator may harm the voltage regulator (or something else). If your alternator is self-excitingand doesn't have a field wire (not to be mistaken for the dash light wire), then you're more or less screwed. Someone here tried re-soldering ther electronics of a self-exciting alt, but I'm not sure if it worked.

[unixrocks]

I think your gains would really depend on a number of factors too - lot of people pull their alternator entirely (mostly for racing) because the engine still has to drive the alternator even if its not being used and puts drag on the engine.

I played with going alternator-less but I couldnt find a belt that would work and I didnt want to put a pulley in place of the alternator because I wanted to be able to re-belt for long drives (pretty simple matter with the Ford escort if you have a breaker bar - takes about 5 mins)

So..I gave up.

[Automcdonough]

This is a bad idea, too many undesirable side effects (other than the obvious dead battery risk) for negligible gains.