Removing Voltage Reg

[RyansToy]

Anything I should be aware of before I remove this and the harness connector? Truck already has an alternator.

[frankslagoon]

I think a 68 still needs a reg. unless you upgraded to the internal reg. alt.

[RyansToy]

So according to this website;
http://www.wallaceracing.com/alt-conversion.html

If there are 4 wires, it is a generator, and if it is 3 wires, then it has the regulator built in?

[frankslagoon]

I'm pretty sure ya don't have a gen. there are actually 3 styles of alt. now days. you have the ext. reg. type and want to go to the next style. internal reg. type that gm started around 73 I think. use the search engine at the top of the page and type in alt. conversion. some of the boys(girls) have come up with some very clean and easy conversions. don't settle for the first wireing diagram ya see. some are better then others.

[VetteVet]

Originally Posted by RyansToy

Anything I should be aware of before I remove this and the harness connector? Truck already has an alternator.

If you have this alternator you need the regulator.



If you have this one it has the regulator internally, and you don't need the regulator, but as stated above, the wiring depends on how the alternator was converted. This is the 12SI model and is better than the 10 SI which came after the externally regulated alternator in the first picture.



Here is how I convert mine.
Take the brown wire off the regulator plug and run it to the no.1 terminal on the SI alternator. Then take the red wire off the regulator plug and run it to the no. 2 terminal on the alternator terminal. The brown wire comes from the firewall block and the red wire comes from the battery, regulator, alternator, and cab power junction.

[firedemon]

Originally Posted by VetteVet

If you have this alternator you need the regulator.

Attachment 1538288

If you have this one it has the regulator internally, and you don't need the regulator, but as stated above, the wiring depends on how the alternator was converted. This is the 12SI model and is better than the 10 SI which came after the externally regulated alternator in the first picture.

Attachment 1538289

Here is how I convert mine.
Take the brown wire off the regulator plug and run it to the no.1 terminal on the SI alternator. Then take the red wire off the regulator plug and run it to the no. 2 terminal on the alternator terminal. The brown wire comes from the firewall block and the red wire comes from the battery, regulator, alternator, and cab power junction.


Attachment 1538291

just to simplify things couldn't I just run a short jumper from the battery terminal to number 2 just to eliminate one more wire from my harness

[VetteVet]

Originally Posted by firedemon

just to simplify things couldn't I just run a short jumper from the battery terminal to number 2 just to eliminate one more wire from my harness

Yes you can and a lot of guys do it that way and even some vendors tell you to do it in their instructions, Painless wiring for one. The only problem doing it that way is that this is the sensing wire for the internal regulator and it's job is to tell the regulator what the voltage drop on the electrical system is from all the loads that are drawing amperage from the system.

If you take the pickup right at the back of the alternator it will always read the output of the alternator AKA the voltage. so it will tell the alternator to maintain that voltage. In fact the voltage drop on the main junction may be as much as 2 volts which means that your light and cooling fans etc may only be getting 10 volts.

If you connect to the main junction the alternator senses the voltage drop and compensates for it by charging longer to supply the amperage that's drawn by the loads. this is a drawback of the one-wire alternators as well.

Mad electric's website has a very good article on voltage sensing titled "remote voltage sensing".

http://www.madelectrical.com/electrical-tech.shtml

[firedemon]

Originally Posted by VetteVet

Yes you can and a lot of guys do it that way and even some vendors tell you to do it in their instructions, Painless wiring for one. The only problem doing it that way is that this is the sensing wire for the internal regulator and it's job is to tell the regulator what the voltage drop on the electrical system is from all the loads that are drawing amperage from the system.

If you take the pickup right at the back of the alternator it will always read the output of the alternator AKA the voltage. so it will tell the alternator to maintain that voltage. In fact the voltage drop on the main junction may be as much as 2 volts which means that your light and cooling fans etc may only be getting 10 volts.

If you connect to the main junction the alternator senses the voltage drop and compensates for it by charging longer to supply the amperage that's drawn by the loads. this is a drawback of the one-wire alternators as well.

Mad electric's website has a very good article on voltage sensing titled "remote voltage sensing".

thanks I thought the brown wire was the sensing wire so I wont go that route . another question would it be better to run the bat terminal back to the battery and leave the number 2 terminal at the junction so it dosent get a reading from the alternator output ? the diagram made me think shorten the connection because theyre both going to the same place . and sorry didn't mean to jack anyones thread

[VetteVet]

Originally Posted by firedemon

thanks I thought the brown wire was the sensing wire so I wont go that route . another question would it be better to run the bat terminal back to the battery and leave the number 2 terminal at the junction so it dosent get a reading from the alternator output ? the diagram made me think shorten the connection because theyre both going to the same place . and sorry didn't mean to jack anyones thread

I would not advise doing that because the sensing wire will read the total voltage at the junction not just the alternator wire output at the alternator.
Here is a common myth in the auto electric world. ( The battery supplies all the charging current to the electric system and the alternator recharges the battery).

It doesn't work quite that way. The alternator supplies most of the needs for the electrical system and the battery acts as a backup to keep a constant current level. At the same time the alternator supplies a small charging amperage to keep the battery at full charge. That's the purpose of the small 12 gauge red wire that runs from the passenger fender junction to the main junction.

If you were to feed the battery directly from the alternator and then feed the system from the battery, all the current for the system would go through the small 12 gauge wire from the battery positive to the main junction. Not only would that not be sufficient for all but the most stock systems but it would circumvent the wiring and the purpose for the battery gauge ( ammeter).

I believe that forum ethics dictates that the OP of the thread owns the thread, and hi=jacking refers to another poster coming in and changing the conversation to another subject and more or less taking over the thread. When the consensus of the thread isn't violated, I don't call that hi-jacking. Especially if the OP is still given first consideration.
In this case he hasn't responded in a while so I wouldn't think he would mind.

But I digress.

[Dustytrix]

Following

[mike16]

do disconnect the battery first. Service it and charge it while your working on your system