Isolating Alternator for trunk mount battery

[Badass442]

I have just finished mounting my battery in the trunk with the main kill switch mounted on the rear bumper. The installation went fine so I thought I would try it by turning the switch when the car was running. The car KEPT running when I turned the switch. I thought about it and concluded that I needed to isolated the charge wire from the alternator to the same side as the battery lead on the kill switch. I have done this as well but have not tried the kill test again yet.

I am using the factory amp gauge in the gauge cluster and also using the factory plug on the alternator. It has a red wire that comes out of the plug (about 4" long) and bolts to the back of the alternator with the "charge" wire that I run back to the battery side of the kill switch.Of coarse I dis connected original "charge" wire and tied it off. The other smaller wire on the plug (brown) goes to the gauge.

The alternator I am using was new last year as a 130 amp replacement (instead of a one wire alt)
So after explaining what I have done here my question is(before trying the kill test)
Is using that factory style plug going to cause any problems or will I have to go to a one wire alternator?
Done this before?
Thanks!!!

 

[grizwald]

i ran a 4 guage wire from the alt to the shut off switch instead of to the starter.

 

[grizwald]

after re-reading your origional post...i don't think i even came close to answering your question ](*,) .

 

[Doober]

Yes, it would need to be on the battery side of the switch. If it's wired to the other side the alternator will keep powering the car. Basically it would be the same as if you were running the original battery/cables/alternator setup, and disconnected the cable from the battery. That cable would still be connected to the rest of the car with the alternator, and it would keep running.

 

[Doober]

So, are you still using the SI style alternator, that has these plugs?

Wired as it is in that pic is fine. If you disconnected the red wire it would not charge.

 

[Doober]

Showing off my mad paint skills...

 

[Badass442]

Showing off my mad paint skills...

Thanks for the pics and diagrams! It now shuts off when I turn the master switch. I was worried about "feedback" through the plug but not a problem!
Cheers!
Badass442

 

[James Bond]

I've never seen that red wire looped like that before.
From my undstanding, the function of the red wire is to sense the charge voltage at the main supply junction for the car. if its connected to the back of the alternator and the charge wire is connected elsewhere, then it isn't compensating the voltage drop of the charge wire. the size and length of the charge wire are to be such that the resistance is equal to the reistance of the battery wire from the junction to the battery. this way the voltage drop is equal and the battery is supplied the correct voltage.

 

[Doober]

Have you taken a look at where that red wire runs to? If he connected it that way, the red wire would have to be run all the way back to the battery, or tied into the harness somewhere near the front of the car. It's hooked up like that on my buddy's '00 TJ and it's running fine.

http://www.1957-chevrolet-alternator-conversion.com/remote-voltage-sensing.html

 

[James Bond]

the red wire just needs to connect to the starter along with the battery wire. the field wire needs to be interupted.

http://www.longacreracing.com/instructions/text/4578PI.pdf