electronic voltage regulator required with higher amp alt on my 68?

[grdprx]

I'm a little twisted around on the alternator issue.  I had a square back in my box of parts when I bought my 68, had it tested, says it was good.  So I've noticed that the battery won't hold a charge, got that tested, it also passed.  Checked voltage while it's running, only registers 10.7 volts at both the alt side and the battery side.  Battery was at 12.6 prior to starting.  I did the red neck test, pulled the negative cable off the battery while it was running; car died immediately.  The alternator is a dual pulley, and the guy at Oreilly's said that means it's the higher amped one, is that true?  Think he said 114 amps.  I had it re-tested today to double check.

I have the 68 manual square type voltage regulator, could that be the problem since I have a higher amperage alt?  I have one of the field connectors grounded so it is compatible with my 68.  I'm working down the list of possible problems to resolve this. 

[charger Downunder]

Charge the battery up and leave it out of the car and see if the charge drops after a few days if so bad battery.
When the battery is in the car and key off, check if you have a wiring fault something running and draining the battery.

[Chryco Psycho]

it means the alternator is not charging , so either ti is wired wrong or it doesn't work , a 68 should have a single field alternator meaning there is a 12v feed from the regulator & the second field is grounded . if you have two spade terminals on the back of the alternator you can either ground 1 & use the 68 reg or switch to the 70 up reg & feed 12v to both the field & reg & then the second wire from the alt to the reg to ground through the reg

[grdprx]

I forgot to mention that part, I do have one of the spades grounded.  I'll have to dig into a wiring issue it seems.  Wasn't sure about that high of an amperage on the 68 regulator.  Sounds ok since I have the spade grounded.

Any recommendations on where to start looking for a wiring problem?  I saw a post regarding the ground behind the voltage regulator...

[Charger RT]

I would start by checking voltage at the battery then again at the battery stud on the alternator. If not close to each other I would start by checking the bulkhead connector. The charging system wire goes through it twice and is common to burn them especially when higher amp alternators are used. Also check the voltage at the regulator. The wire in should be close to battery voltage. The wire coming out should be close to battery voltage if the regulator circuit IS WORKING but the alternator is NOT charging. If it is charging that voltage can be much lower and will vary depending on electrical load.
Tim

[elacruze]

Start with the alternator itself; use a multimeter to test continuity between the field terminals on the alternator (of course they must be disconnected first). You should have a circuit. Then test between each terminal and the body of the alternator for circuit; you should have none, if you do then the field is grounded. If your alternator passes both, and it should if you had it tested, then test how much voltage you have coming from the regulator; if you have none, then either your regulator is bad, it's ungrounded, or the power to the regulator is absent.

A sure test to isolate the regulator as the problem is to disconnect the harness lead at the alternator, and with the engine running use a jumper wire to connect the field terminal to battery positive. You must not leave the jumper connected more than a couple seconds, and you should not rev the engine any more than necessary to prove output since the alternator will be unregulated and output will be at maximum. Once you've isolated the problem, move downstream one connection at a time until you've confirmed or disproved each one and discovered the fault.

Squareback alternators are max 78 amps.

[grdprx]

Cool!  Thank you very much for the detailed diagnosis steps!  I'll get to work on it today.

[grdprx]

Ok, I checked voltage at the battery and alt, 12.3 and 12.1 at the alt.  Close enough I think.  When I start the car, that's where I see the problem.  I get 10.8 volts off the alt at the highest, bounces around from 10.2, 10.5 to 10.8.  At the regulator, both sides read 10.5.  Battery was at 12.0

The reason I started looking into the charging issue, I drove the Charger in to work, fired her up like 5 times to show off to co-workers and such...  Had to stop for gas on the way home, and the battery didn't have enough juice to start from there; had to get a jump.  So I started by getting the alternator tested, but if I'm only getting 10.8 off it at idle, is it really good?  And how did it pass on a test?

Testing the circuit on the alt, there was continuity between the two fields, yet they both had continuity to the body of the alt!  Not sure how that happens since it passed the test at O'reilly's...

[elacruze]

ok, the continuity to ground is bad, but that's not the whole story. It can be caused by dirty windings, robbing current from the field circuit and resulting in poor output particularly at low RPM. Blow the alt out with electric motor cleaner and compressed air, and recheck. These alts are pretty famous for low output at idle anyway, so you need all the help you can get.

What voltage did you see when you jumped the alt field to battery +?

[grdprx]

What voltage did you see when you jumped the alt field to battery +?

I didn't get to that step since the fields were grounded.  Have to dig around for a jump wire, so I take the field wire off the back of the alt while it's running, then jump it?  where do I measure voltage, on the alt side?

I'll have to clean it out as you recomended.

[grdprx]

Well, I pulled a rookie move..  I didn't reconnect the field wire once I started the engine yesterday, so I didn't have a correct reading at the voltage regulator.

With the field wire hooked up to the back of the alt, the green wire only read 2.5 at the regulator!  Blue side was 10.5 which matched yesterday's reading.  I also took a reading off the alt where the green wire attaches, it was also 2.5.

Would this be related to the grounding of both field terminals to the alt body?

[elacruze]

I'm not sure I understand how you have it hooked up.

You should have one field terminal connected to your mechanical voltage regulator, and one field terminal connected to ground. If they both go to ground nothing can happen, and your regulator will short to ground every time it activates.

[grdprx]

I do have the green wire on the factory harness going to one field terminal, the other is grounded.  I have a new engine wire harness from Year One on the car, so those wires should be good. 

I was referring to the fact that I tested continuity between each field terminal and the case of the alternator earlier, and the tested positive.  I have not yet cleaned the alternator, I don't have compressed air at home.

I was just wondering if because both those fields had a circuit, which I understand as being grounded, if that was the problem. 

I apoligize if confused things, I sometimes type faster than I'm thinking.

[elacruze]

Yes, if the field terminals are not completely isolated from the case, you can lose part or all of your function.

[Nacho-RT74]

ok, sorry I was a little bit lazy about this thread, dunno why. will post something

earlier alts setups got one brush directly bolted to chassis ( grounded ) and one isolated. Which ever brush you test for continuity, will test CONTINUITY with chassis, even the isolated one due is being allways making contact with the non isolated one throught the rotor. True, won't give you 0 ohms, but maybe 8 to 12 ohms which is the rotor resistance.

earliers setups alts ( with mech regs, or same setup with modern electronics inside ) gets constant ground through the grounded brush, and the isolated brush will get a positive pulsating signal ( produced by the mech reg, like a relay ) or "regulated" which is what changes the magnetic field intensity inside changing of course the output from alt as required.

Lates setup is a diff story. They get positive constant from the key, and regulated negative or ground from regulator. Thats why on lates they get both brushes isolated. Positive brush needing of course to be isolated from ground, and negative brush needing also to be isolated being this now the regulated source.

On both setups the GREEN WIRE is the regulated source, positive en earliers, and negative on laters

If you full fill both brushes fields with each signal ( which means bypassing reg ), you should get full juice from alt

[grdprx]

What voltage did you see when you jumped the alt field to battery +?

Taking some time again to look into this problem I'm having.  I jumped the alt field to battery, got 14v.  So I'm guessing that means the alt is good.  Does this then mean the culprit is my regulator?

[A383Wing]

I would say yes, or possibly bad or broken wire somewhere

Bryan

[nrt69]

these electrical/wiring problems are incredibly frustrating.

Ive got a new battery and new alternator and im still getting a discharge at idle and under load. its severe when using the signals and lights. Ive owned my 69 Charger for almost 20 yrs now and have always had some discharge with the lights but never as bad as it is now. Any suggestions? I keep trying to save the link from Nacho explaining why this happens but for some reason the link never works.  Could someone send me that link and a good one about the GM one wire?

Ill try my volt regulator and old wires to my alternator (as mentioned above) in the meantime because i dont know how the volt reg is and the green wire to the alt is old and cracked.

[grdprx]

I would start by checking voltage at the battery then again at the battery stud on the alternator. If not close to each other I would start by checking the bulkhead connector. The charging system wire goes through it twice and is common to burn them especially when higher amp alternators are used. Also check the voltage at the regulator. The wire in should be close to battery voltage. The wire coming out should be close to battery voltage if the regulator circuit IS WORKING but the alternator is NOT charging. If it is charging that voltage can be much lower and will vary depending on electrical load.
Tim

Which wires should I check on the bulkhead?  Am I looking for a variation in voltage somewhere?  This electrical stuff sometimes gets the best of me....

[Charger RT]

the wires are the battery wire from the stud on the alternator. just follow it to the firewall (bulkhead connector) and the one off the starter relay going to the firewall.

With the new battery and stuff try rechecking the voltage readings at the large wire on the alternator and again at the battery. The difference this time is hold engine rpm at about 1500 for both tests and have the lights on. With the way it was before the test results mean nothing discharging.
Tim

[elacruze]

from the 'home' page, search 'bulkhead connector' and you'll find threads galore with every bit of information you might need.

[grdprx]

Out here taking some measurements.  With the ignition off, the batt is at 12.2.  Same at starter relay and on the other end of the fuse able link at bulkhead.  Alt stud and black wire on bulkhead is 11.4.

With the car running, batt, starter relay, and fuseable link is 12.1.  Alt stud reads 9.5-9.6.  Blue wire on regulator is 9.3-9.5.  Green wire is 2.7 at regulator and field connector.

Is this pointing to a faulty regulator?  Or do I have a draw somewhere, because the alt is a volt short with everything off?

[Charger RT]

Out here taking some measurements.  With the ignition off, the batt is at 12.2.  Same at starter relay and on the other end of the fuse able link at bulkhead.  Alt stud and black wire on bulkhead is 11.4.

With the car running, batt, starter relay, and fuseable link is 12.1.  Alt stud reads 9.5-9.6.  Blue wire on regulator is 9.3-9.5.  Green wire is 2.7 at regulator and field connector.

Is this pointing to a faulty regulator?  Or do I have a draw somewhere, because the alt is a volt short with everything off?

you are dropping 2.5 volts. The first place to start is the bulkhead connector. Since the regulator voltage is low I would bet everything inside the car is low. This drop needs fixed. Nacho has done quite a few threads on the charging system. He has several on his parallel charging circuit. It adds 2 parallel wire to take some of the load off the 2 wires that normally burn at the bulkhead connector. You would still need to locate your drop and fix that but his parallel setup would help prevent it from doing it again. here is a link to one of his threads. http://www.dodgecharger.com/forum/index.php/topic,33574.0.html I would bet Nacho will chime in and help. I would think his diagrams will help you locate the 2 wires at the connector.

With the voltage drop you can't say the regulator is good or bad we will have to wait until the drop is fixed and it gets a good 12 volts. Also you don't have a draw. A draw would drain the battery due to some thing drawing power. You have a drop due to high resistance in a circuit.
Tim

[grdprx]

Ok, any suggestions to locate the drop?  What should I look for?  I need to do this with the alternator and car running, as that's when the drop occurs?  I think I tested it with the ignition on, car not running; and it was still in the 11 volt range on the alt stud.  I may have to double check that.

One thing to note, I disconnect the negative batt cable while the car isn't in use...

[Nacho-RT74]

[ This drop needs fixed. Nacho has done quite a few threads on the charging system. He has several on his parallel charging circuit. It adds 2 parallel wire to take some of the load off the 2 wires that normally burn at the bulkhead connector. You would still need to locate your drop and fix that but his parallel setup would help prevent it from doing it again. here is a link to one of his threads. http://www.dodgecharger.com/forum/index.php/topic,33574.0.html I would bet Nacho will chime in and help. I would think his diagrams will help you locate the 2 wires at the connector.

Thanks. Dunno why I forgot to recheck this thread

I'd try to full field the alt to see what happens