Burning Up Voltage Regulators *Update & PSA*

[Dano 1]

Background: '69 Charger, 440 from a '71 Imperial, stock style electronic ignition conversion, ammeter bypassed with a heavy gauge charge wire from the alternator directly to the battery post, ammeter wires connected under the dash and properly insulated. Alternator is a 50amp single field stock replacement (https://www.autozone.com/batteries-starting-and-charging/alternator/duralast-remanufactured-alternator-dl7001/333153_940170_0)

I went to start my car after a drive the other day and found the battery to be totally dead. A quick check of the voltage with the car running (after a jump) showed that the alternator was not charging as it should. I had 12v at the voltage regulator but was not getting any output from it at the regulator or the field post on the alternator. Figuring the regulator was just bad I picked up a new one and initially everything seemed fine, had a good strong charge at the battery at idle and with rpm.
After about 30 seconds I noticed a plume of smoke coming from the brand new regulator so I quickly disconnected it. Here's a breakdown of the diagnostic process so far:

Ran a jumper from chassis ground to regulator case to eliminate any grounding issues, no change.
Ran a bypass wire from the field terminal to the alternator, no change.
No continuity from factory field wire to ground, so no shorts there.
Regulator is pulling ~6amps on the ignition side when the car is running, this seems high to me but I couldn't find a value to confirm.
Verified continuity in the harness between regulator, ballast resistor, and firewall connector.
Firewall connector pins all cleaned and no signs of overheating or damage.
All other accessories/electrical systems functioning normally.
Brand new ground strap between firewall and engine.
No other signs of shorts or obvious issues with the stock wiring so I am officially stumped.
Any ideas?

[stripedelete]

You'll likely look past the alternator because it's new or newly rebuilt.  Before you go any further, take it to a rebuilder and have him check it out.   Or, do what I did; burn up several more regulators and then take you're recently rebuilt alternator to a reputable rebuild shop and find out it is the problem...

[b5blue]

Never force the charge system to recharge a dead or discharged starting battery. The system is only to replace starting loss and maintain operation.

[Dano 1]

You'll likely look past the alternator because it's new or newly rebuilt.  Before you go any further, take it to a rebuilder and have him check it out.   Or, do what I did; burn up several more regulators and then take you're recently rebuilt alternator to a reputable rebuild shop and find out it is the problem...

I had the alternator tested by a big-box parts store and it was supposedly fine, I'm sure a proper rebuilder would be able to give me more feedback so I'll have to look around and see if there's someone local. I also ran a jumper from the battery post to the field terminal and it charged like it should.

Never force the charge system to recharge a dead or discharged starting battery. The system is only to replace starting loss and maintain operation.

When I found the battery was dead I put it on charge overnight prior to installing the new voltage regulator so it was never trying to fully re-charge the system.

The battery is brand new but I'm thinking it's worth having tested to see if there's a cell that's intermittently shorting or something else wrong...

[ODZKing]

You'll likely look past the alternator because it's new or newly rebuilt.  Before you go any further, take it to a rebuilder and have him check it out.   Or, do what I did; burn up several more regulators and then take you're recently rebuilt alternator to a reputable rebuild shop and find out it is the problem...

A friend has told me - Tophusis say "part known new, not known good"

[Dano 1]

*Update*
You guys NAILED it. I found a local shop that just rebuilds/repairs starters & alternators with a REAL test bench and sure enough the alternator is DOA. The shop owner said either an internal short or bad diode, so back to the store we go to warranty it. Maybe I'll get a good one this time, who knows!
I wish I had thought to use this guy to rebuild my OEM unit instead of turning it in as a core like a chump 

[Dano 1]

I'm now on reman alternator #3 and believe I have FINALLY gotten to the bottom of this thing. I took alternator #3 to the rebuilder and it tested ok, in fact it was pushing 100amps not the 60amps it's rated at. We started talking about my regulator issues and hashing things out, when a lightbulb went off in the shop owner's head. He said this reman alternator was pulling 7 amps to the field. The 1969 and down regulators are only rated for 5 amps which means this alternator was pulling too much current through the early style regulator which the rebuilder suspects would be enough to fry the regulator. His opinion is that they simply don't make 5 amp field windings anymore because there's simply no demand and instead reman everything with 7 amp units which will fry regulators. His recommendation was to swap over to the 70+ dual field alternator/regulator that would all be matched and rated for the correct current.

Moral of the story is most/all reman 1969-down alternators will NOT work with the early style regulators and will likely lead to issues.

Also, if anyone needs alternator/starter rebuilding service absolutely use Carolina Auto Electric, the owner is a standup guy and absolutely knows his stuff: http://www.carolina-autoelectric.com/

[ODZKing]

Dano, glad you found the issue. Another thought I had was changing over to the new style regulator as the old points ones are prone to burning up easily. They use new electronics and are available in the old style cases so it looks original. It's what I have on my 67, in fact, I keep an extra in the trunk on trips.
http://www.4secondsflat.com/regulator_tech.html

[Dano 1]

I actually did try one of the solid state units, a VR706 from Autozone and while that one didn't start smoking it did lead to a dangerous over-charging situation. I got back from a drive and noticed battery acid coming out the vents and a quick voltage check showed the alternator with the electronic regulator pushing 17+ volts at fast idle. I think the current that alternator was pulling through the field was too much for even the electronic version.

I swapped over to a 70+ dual field alternator and voltage regulator last night and all seems well. Except of course for a new belt misalignment problem due to the pulley on the 'new' alternator not being installed to the correct depth 

[Nacho-RT74]

just FYI... do you know you could convert your old alt into a dual field system just using a drill and getting the propper brush and isolation assembly ?

this is an old thread I made explaining that

http://www.dodgecharger.com/forum/index.php?topic=98367.0