62 C10 external to internal regulator question

[sthaden]

Previous owner already had internal regulator alternator installed but also had wiring connected to external regulator. Assuming this is why my battery won't stay charged. I wired the alternator to the positive battery terminal and the ignition coil, but what do I do with the wires that were connected to the external regulator? I'm assuming the 2 small wires can be taped off, but what to do with the heavy black and red wires? The red wire also has a split to the horn relay below the ext. alternator. Black should be ground wire?

[gofastnut]

This should cover it really well:
http://67-72chevytrucks.com/vboard/s...d.php?t=119379

[gofastnut]

Or this one, just a little different take on the same thing:
http://www.hotrodders.com/forum/exte...el-220249.html

[sthaden]

You really overestimate my ability! At this point I just wish that the wires I have were the same colors as the wiring instruction link you provided. Once I disconnected the external regulator everything's dead. Wish I would have taken a picture BEFORE I disconnected it!

[tincan1966]

Normally there is a horn relay mounted just above the regulator-it's a metal box shaped. Maybe just couldn't see it in your pictures.
Anyway there "should" be a large wire coming across the radiator support from the battery to it. It attaches to the relay on the screw terminals. The other RED wires attach to the other screw terminals-that provides battery power to the ALT and IGN Switch. Those have to be connected in order for the truck to run.

Once that is done, you need to find the "key on" wire that went to the old regulator. It will not have a full 12V+. Connect it to the white wire on the Internally regulated alt plug in.
DO NOT connect to the ignition coil 12V+ wire. The resistance wire will not be able to sustain the constant load of the ignition and alternator and will either burn out or the low voltage could damage the alt or the coil-either one will leave you stranded.
Connect the red wire of the alt plug in(new alt) to the BATT terminal on alt. The other red wire at ALT should go up to the horn relay, previously mentioned.
This will get you going and you can remove the unused wiring between the regulator and the old alt.

Hope this helps you out.

[Sharps40]

Maybe this will help.....Works for 10SI, 12SI alternators on idiot light dashboards. (Gauge dashes are the same for wireing but need a diode/or resistor, i forget which, in the brown line to excite the alternator)...i.e. removal of old external regulator and associated alternator, wireing up the replacement.

Kill the battery by disconnecting it, pull both so you can run the sensing wire back to positive in order for the alternator to reulate for voltage drop in the system. (Many just hook wire one to the batt terminal of the alternator, it works but dosn't provide full voltage to the battery and can leave you perpetually under charged. Might as well do it right).



Remove the factory tape from the wiring harness, alternator to firewall to old external regulator.



Heres the parts, new 12SI alternator, Alternator pigtail for the 12 SI and a spool of 14g wire for the sensing line.




Hook up the original red wire from the positive terminal of the battery to the Batt terminal of the 12SI.



Unbolt the old external regulator from the radiator support.



Cut the small red wire from the old regulator to the horn relay. Remove the black ground wire that ran between the horn relay and the old regulator. Cut the brown wire running from the dash light to the external regulator, cut it at the external regulator. Only the brown wire from the original external regularor harness will be retained. The old regulator and the rest of the old harness are no longer needed...give em to a 100 point restorer or toss em in the trash.



With the old wires that used to run from terminals 1 and 2 of the old alternator and the wires cut above, remove the unneeded external regulator harnerss.



Solder the brown wire from the dash light to the small lead (#1) of the new 12SI pigtail. Solder the sensing wire you bought to the large wire of the new 12SI pigtail, (#2)



Route the sensing wire from the alternator terminal 2 along the Batt wire and connect to the + terminal of the battery. Reconnect both posts of the battery.



Check all connections, wrap the harness and turn the key, Gen light should glow, start the motor, Gen light goes out...check voltage at the battery terminals, it should be 14.5 volts if its working right.

[tincan1966]

Yep that will work too, I just don't run the extra wiring.

[Sharps40]

Yes. Some folks hook the sensing wire, (Alt #2 wire) directly to the Alt Batt and it works fine/measures load.

Others extend the sensing wire to the + side of the battery and it works fine/measures load.

[sthaden]

Wow, this is all great advice! It's quite obvious that the wiring wasn't done correctly when converted to an alternator. I'll use these notes and dig in to it on Saturday and hopefully will have this problem fixed. I'll let you know how it goes. Thanks for your help!

[Sharps40]

Good luck, post up pics.

[T2vigil]

Thanks for the supper wright-up.

[Snailed]

Originally Posted by Sharps40

Yes. Some folks hook the sensing wire, (Alt #2 wire) directly to the Alt Batt and it works fine/measures load.

I don't think it works fine or measures it correctly.

You need to have the sense wire connect closer to where the loads are otherwise the alternator will not put out what it should.

[tincan1966]

Originally Posted by Snailed

I don't think it works fine or measures it correctly.

You need to have the sense wire connect closer to where the loads are otherwise the alternator will not put out what it should.

I've been wiring them this way for 15 years and they work just fine.
If the output wire from the alt BATT terminal goes to the battery directly, what are you gaining by running another wire parallel to it from the same starting point to the battery? The only way it would sense load any differently is if you were connecting it thru a shorter length of wire, which you are not. It makes a redundant circuit that is not needed.
I know I will get a hundred replies of "well, so and so said to do it this way on his website..."
Not saying either way is right, wrong or indifferent, just offered an optional way of doing it.

[Sharps40]

Well, fellas, don't know...I just followed the write ups on this forum, ones I found indicated a preference for sensing at the battery since all loads are down stream of the box yer tryin to feed enough juice to recharge.. So, that's how I did it. Both ways work evidently so pick yer flavor and drink yer koolaid. Ultimately it ain't worth much discussion as I spect there's little or no empirical evidence that one way is better than the other. If I bought a truck short wired, I wouldn't be in any hurry to extend it that's for sure.

[Sharps40]

I just reread that. I ain't tryin to be harsh. Just figure where the sensing wire go's to is pretty much a moot discussion....not a discussion to loose friends over.

[Snailed]

Haha, well maybe we can all be friends and wire our alternators how ever we want.

It does function with it wired both ways. It functions better with it done the way it was designed, letting the sense wire compensate for voltage drop. The fact that the pin is even on the outside of the alternator is plenty of evidence that it matters. If it was supposed to be wired to the Bat terminal on the alt it would be internal from the manufacturer.

This explains it pretty well. http://www.madelectrical.com/electri...esensing.shtml

[tincan1966]

Originally Posted by Snailed

Haha, well maybe we can all be friends and wire our alternators how ever we want.

It does function with it wired both ways. It functions better with it done the way it was designed, letting the sense wire compensate for voltage drop. The fact that the pin is even on the outside of the alternator is plenty of evidence that it matters. If it was supposed to be wired to the Bat terminal on the alt it would be internal from the manufacturer.

This explains it pretty well. http://www.madelectrical.com/electri...esensing.shtml

That is a great article and very well explained.
However: how many people actually have a similar application as their test vehicle? Anyone that wires vehicles professionally will tell you that you will experience voltage drop with longer wires. Dual batteries mounted at the rear of the vehicle and a 12' charge wire from the alternator are at least double the distance that these trucks have. And how many of us are running 5 electrical fans? In my opinion in the final test in that article, with everything on full output, a 1V drop isn't bad. Even GM says that voltage above 13.0-13.3 at the battery is acceptable, and if fact, they wire the sensing wire to the BATT terminal at the alternator on several years for vehicle with 10 and 12 SI alts.
I would much rather have the alternator charge a little bit less and last longer, than consistently hold it in a position to charge at maximum, which is basically what you are asking it to do to charge at 14.2+ all the time

I will never win this debate, I am very well aware, and that is fine. I always am merely trying to explain another option As with anything, there are many ways to do it, all of which work and work well.

I actually agree with Sharps post and his explanations are very detailed, very well described(still wish I was the guy selling him electrical tape, tho, LOL) Sharps is committed to building a vehicle for the long-haul, everyday, daily driver use, which is an upgrade to the entire vehicle from where these trucks start from. And to me that is way more important than "...it'll work for now..."

[Sharps40]

I am finding that a roll of electrical tape actually goes farther than a tube of Blugoo. But, electrical tape don't seal as well as Blugoo.

Neither of em come off easy though!

I love em both, very much!

[Sharps40]

What I really need for Total Billy Bad Ass factor, to go with my ESS CrossBow EyePro is Digital Camo Electrical Tape.

[sthaden]

I got home early today so I followed tin can's recipe for success and after a couple of hours...it works! No, I probably didn't wire it like a pro, but I'm happy. Thanks again to all.

[Sharps40]

Well, see there ya go, yer 10SI is up an runnin and later on ya can go back, pull the unused harness and regulator and clean it all up pretty like. For now enjoy it, drive it and drink a cold frosty and smoke a cigar cause ya fixed it free!

Be sure ya explain how much munny yer savin so yer wife'll be cool with buyin a new 38 special belly gun for long rides in the country...for snakes ya know...

[sthaden]

You're right it's a fine feeling to have done it yourself. This site is the best...
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[gofastnut]

I was re-reading this thread because I was going to install my 94 amp 1wire. But after doing some reading (don't act so surprised, you thought I was just here for the pictures!), I've found that the 3 wire set up is much better.
So tomorrow I'm gonna trade in my 7294-1W for a 7294-12 for a difference of $8.
Not to beat a dead horse, but I did find this article interesting on the voltage sensing part:
http://bob_skelly.home.comcast.net/~...ternator1.html
It's a 1/3 to half way down the page.
Here's another interesting read: http://www.madelectrical.com/electri...esensing.shtml
I've got a few buddies that just run the #2 wire right back to the BATT post. I think I'm gonna be different and run it farther away.
Again, thanks for the info guys!

[Sharps40]

Remote sensing is one of them scabbed over cuts that we're always gonna pick at. Sort of like the difference between 9mm and 45 ACP in a gun fight. I think, as long as yer truck is reliable and its performance suits ya, hook that wire up wheresome ever ya like.

[gofastnut]

Yep, and it's a far cry better than not having a great forum with all these helpful guys!