THUNDERZ Posted July 12, 2007 Share Posted July 12, 2007 Can anyone tell me where the field wire or "sense" wire should go to within the car( 78' 280Z )? Right now it is going right to the positive terminal on the alternator...so I dont think it is able to sense any load that gets put onto the system. The alternator is a AC Delco 10SI or 12SI ...the motor is a 350 with a edelbrock 4bbl carb...it has the HEI dizzy. Quote Link to comment Share on other sites More sharing options...
Bartman Posted July 12, 2007 Share Posted July 12, 2007 I have mine connected to the ground side of a charge light with the positive side of the light connected to ignition hot. This way the light gives you an indication if it's charging or not. When the ignition is on (but the engine isn't running) the alternator light is on because the alternator grounds the sense wire. When the car starts the sense wire switches to positive and senses load while the light goes out since it is detecting two positives. Quote Link to comment Share on other sites More sharing options...
Teekass Posted July 13, 2007 Share Posted July 13, 2007 Can anyone tell me where the field wire or "sense" wire should go to within the car( 78' 280Z )? Right now it is going right to the positive terminal on the alternator...so I dont think it is able to sense any load that gets put onto the system. The alternator is a AC Delco 10SI or 12SI ...the motor is a 350 with a edelbrock 4bbl carb...it has the HEI dizzy. The field and sense wire are 2 different wires. The field wire is the one closest to the positive output stud on the back of the alternator, and should be connected to a switched hot battery source (but not the lead to the distributor, otherwise the engine will not cut off with the ignition switch......guess how I know that, LOL). The sense wire is the one furthest from the output stud, and should be wired just as Bartman said......If you don't have an alternator light, I would connect it to the positive battery post as you mentioned. I've read somewhere that you don't have to connect the field wire to anything. After starting the engine, you might have to rev to 3,000 rpms or so to excite the alternator. I don't know that first hand, but I kinda like the sound of NOT having to do that. And Bartman, thanks for explaining how the alternator light works. I thought that was how you hooked it up, but never really understood how it worked.....makes sense (pardon the pun) now. Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted July 13, 2007 Author Share Posted July 13, 2007 The field and sense wire are 2 different wires. The field wire is the one closest to the positive output stud on the back of the alternator, and should be connected to a switched hot battery source (but not the lead to the distributor, otherwise the engine will not cut off with the ignition switch......guess how I know that, LOL). The sense wire is the one furthest from the output stud, and should be wired just as Bartman said......If you don't have an alternator light, I would connect it to the positive battery post as you mentioned. I've read somewhere that you don't have to connect the field wire to anything. After starting the engine, you might have to rev to 3,000 rpms or so to excite the alternator. I don't know that first hand, but I kinda like the sound of NOT having to do that. And Bartman, thanks for explaining how the alternator light works. I thought that was how you hooked it up, but never really understood how it worked.....makes sense (pardon the pun) now. As far as I know the sense wire is supposed to detect load on the electrical system....so I think it must be there to tell the alternator when to up the voltage...so I think it needs to be hooked up to something. My understanding is that if the sense wire is hooked to the positive lead on the alternator that it will never sense a load and the rest of the car will suffer from under voltage as load is applied...anyone care to enlighten me http://forums.hybridz.org/showthread.php?t=106432 Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted July 13, 2007 Share Posted July 13, 2007 As far as I know the sense wire is supposed to detect load on the electrical system....so I think it must be there to tell the alternator when to up the voltage...so I think it needs to be hooked up to something. My understanding is that if the sense wire is hooked to the positive lead on the alternator that it will never sense a load and the rest of the car will suffer from under voltage as load is applied...anyone care to enlighten me http://forums.hybridz.org/showthread.php?t=106432 I agree with what you say. The internal regulator will try to maintain the proper voltage at whatever point in the system the sense wire is hooked up. If that is the alternator output, you will get the 14.5 v there. If a heavy load is placed on the alternator, the current flow will cause a voltage drop across the alternator wire. The regulator will keep the alt output at 14.5 v, but the rest of the system might now be operating at 12 or even 10 volts. Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted July 13, 2007 Author Share Posted July 13, 2007 I agree with what you say. The internal regulator will try to maintain the proper voltage at whatever point in the system the sense wire is hooked up. If that is the alternator output, you will get the 14.5 v there. If a heavy load is placed on the alternator, the current flow will cause a voltage drop across the alternator wire. The regulator will keep the alt output at 14.5 v, but the rest of the system might now be operating at 12 or even 10 volts. My next question is where should the sense wire hook into the electrical system? Quote Link to comment Share on other sites More sharing options...
Bartman Posted July 13, 2007 Share Posted July 13, 2007 My next question is where should the sense wire hook into the electrical system?LIke I stated in my post above, you hook it to an ignition hot from your existing wiring system. Whether you use a light or not is up to you, but either way that's how it detects load. Quote Link to comment Share on other sites More sharing options...
THUNDERZ Posted July 13, 2007 Author Share Posted July 13, 2007 LIke I stated in my post above, you hook it to an ignition hot from your existing wiring system. Whether you use a light or not is up to you, but either way that's how it detects load. What about to the positive battery post? Quote Link to comment Share on other sites More sharing options...
Bartman Posted July 13, 2007 Share Posted July 13, 2007 What about to the positive battery post?If I'm understanding this correctly, if you only have a two wire system and supply power at all time on the sense wire, you can burn up the voltage regulator.http://www.alternatorparts.com/FAQ.htm#how%20to%20wire If you have a three wire system, then you can wire one to the light and one directly to the battery. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted July 13, 2007 Share Posted July 13, 2007 If I'm understanding this correctly, if you only have a two wire system and supply power at all time on the sense wire, you can burn up the voltage regulator.http://www.alternatorparts.com/FAQ.htm#how%20to%20wire If you have a three wire system, then you can wire one to the light and one directly to the battery. I almost posted that in my last post but wasn't sure if it applied to Datsun alternators. I know on the alternators used with LS motors you have to have either a 500 ohm (I think) resisitor or a light bulb in the sense wire line or it will burn up the alternator. Thus the charge light is perfect for the task. Can't use an LED, it has to have some resistance like a bulb does. Quote Link to comment Share on other sites More sharing options...
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