Regulator/ Alternator/ Amp Meter woes = meltdown

[sebarger]

Hey everyone...yes as the title implies, problems in paradise...

First off, a quick self-intro as I am a newbie here :-). After a few years deliberation and much searching, I am the proud owner of my first '68 Charger, 383 3 speed automatic, GL replica . Reading through a bunch of the posts here, I'm getting a crash course on the electrical woes that seem to be this car's Achilles heel so seeking advice on what the problem might be and the best upgrade(s) to do to improve performance and ensure piece of mind (Quick disclaimer - I am a total novice when it comes to anything beyond the basics of electrical systems).

A little background...

We took her on her first day trip a couple of weekends ago and backing into the garage upon our return the engine literally just cut out with no warning. Odd as I would have expected it to be fully charged after a day out and there was no indication of discharge (the amp meter dipped negative now and again but had been pretty much "flat" all day). Turning the key made the tell tale clicking sound as if the battery were dead so put on some jumper cables and bang - she roared back to life.

My electronically savvy friend brought his voltage tester over and he quickly deduced that the regulator was shot. Blue power lead in from ignition was fine showing 5v but nothing was coming out of the other terminal (green lead to the alternator). Further, exciting the green lead to the alternator manually resulted in charge from the alternator so the alternator seemed fine. The regulator appears to be the manual variety and looks like this:

https://www.yearone.com/Product/DisplayProduct/25899

The prior owner indicated he had changed the regulator (he put on a used one) and rebuilt the alternator (two pulley type which I *think* is 60AMP).

Off to the local auto electric shop with regulator in hand. They also verify it's dead and supply me an electronic replacement. When I ask why not a mechanical one, he says he recently fitted an electric one on an old Chrysler limo which worked fine (and I'm thinking perhaps naively that modern tech must be better?).

Interestingly, fitting this leads to the amp meter constantly reading discharge (about -20 at idle) despite the fact that the alternator is actually OVER charging measuring 15.8-15.9v at the battery terminal. Revving up the car brings the amp meter to neutral position but it never goes positive??

Concerned about frying the battery from the over charge, I go back to the auto electric shop and they swap out the electronic one for a mechanical one. This yields us a much more normal 13.5-14v of charge :-) but the amp meter is STILL showing discharge and never goes into the +. Stepping on the brakes or putting on the turn signals while driving causes the the amp meter to dip -20 negative even though the car is charging??

The auto electric shop doesn't have any ideas about the amp meter (we're puzzled as it's charging?) so I figured I just go home and sort that one out later. 10 mins into my journey I see a little smoke emanate from the dash and the amp meter needle disappears (goes wildly off the normal range?). While frantically looking for a place to pull over (not easy in London traffic), the small wisps of smoke disappear and the amp meter comes back to neutral position. I'm thinking that the regulator just went up in smoke and decide to just get back to my garage rather than fight traffic back to the auto electric shop. Upon popping the hood, I'm horrified to see that the casing has basically melted off the green lead from the regulator to the alternator and has literally burnt clean through in one spot. In the process it has done a good job melting some of the other wires on the engine harness which means I'm now in need of one of those as well

My electrically savvy friend came over to inspect the burn damage and offers that given the blue lead into the regulator is fine, the fault must have originated with alternator. Perhaps the regulator sent a bad signal or maybe there is actually a short in the alternator? He's quick to note that there's no fuse in this green lead and suggests we add one to prevent meltdown in the future.

Now that I am forced to replace the wiring harness, I would really like to nail down the source of the issue and replace/ upgrade whatever is necessary with the aim for improved, trouble free performance. My head is spinning from the combination of all the options that seem to be out there. Some people have gone with the GM alternators with the built in regulator, some upgrade to electronic regulator and compatible alternator, some people have also upgraded to a more powerful alternator and then there are these other MOPAR PERFORMANCE DATE CODED VOLTAGE REGULATORs??

http://www.classicindustries.com/mopar/parts/mn2180.html

Sorry for the long winded post! I've never experienced anything like this and was hoping clearly naively that it would be a simple fix. Any insight about how to diagnosis the problem and recommendations for a more modern and reliable (?) upgrade greatly appreciated! Thanks!

[Charger RT]

Most of the electrical issues would not really be issues on these cars if people put on it what it was designed for. The car came with something like a 35 amp alternator. The two connections at the firewall can barely handle that. Putting on a 60 amp alternator and/or adding modern stuff (radio, amp or whatever) will just overload them and they will melt. I will bet you need to fix them. Now I'm not saying put a 35 amp alternator on the car. I have a 60 on my 68 and plan on a 90 amp denso soon.

There are many threads here on the repair of the two wires in the bulkhead connector. Do a search. They will also show you how to add wires to allow the car to use a bigger alternator.

I would use the electronic version of the stock regulator. The wire going into the regulator from the harness should be feeding the regulator 12 volts not 5 to me that is a sign of bulkhead connector issues.
Tim

[Ghoste]

And cleaning the bulkhead connector regularly would also go a LONG way into helping with some of these issues.  Most of these cars still have the original 40 year old wiring and its dried up, hacked up and being asked to do more than it should.

[Chryco Psycho]

or packing the bulkhead connections with di-electric grease so they do not corrode
Possibly the 2 wires to the ammeter were reversed showing discharge , the ciruit boardis marked Red on one terminal , make sure the wires are tight on the ammeter , . you may be able to repair the damaged wires & harness or you can order new harnesses , best repro part is from year one .

[sebarger]

Thanks guys! What an educational process! I have now pretty much read all of the MAD electrical articles front to back and it's nothing short of scary! I'm ready to start putting some of this to practice and first order up for business is the amp meter bypass (http://www.madelectrical.com/electricaltech/amp-gauges.shtml).

Looking at my bulkhead connectors, there wasn't much oxidation, but the BLACK lead from the alternator that goes into the P slot on the middle connector definitely shows signs of meltdown  I haven't checked behind the dash yet...almost scared to see what it looks like behind the amp meter...

Tim, when you say that you "would use the electronic version of the stock regulator", can I confirm you mean this one - RX346?

https://www.yearone.com/Product/DisplayProduct/63968

There seem to be a HUGE selection out there??

https://www.yearone.com/Catalog/Filter/1505

Also, is there a way to shunt (?) the amp meter so that it still puts out a reading or should I just modernize, toss it and get someone to put in an authentic looking volt meter in its place?

[mhinders]

Also, is there a way to shunt (?) the amp meter so that it still puts out a reading or should I just modernize, toss it and get someone to put in an authentic looking volt meter in its place?

Yes, it's quite common to use shunts for bigger currents, I have it in my boat, where I have built and installed all myself, using general, low cost instruments. You can't use your original ammeter for this purpose.

You can have an accurate amp-meter using a shunt for the bulk of the current. This "amp-meter" will actually show the voltage drop across the shunt, but the scale will show Amperes.

Just an example, use your own numbers: Your current to the battery is 50 Amps. You have a shunt which is 0.01 Ohms. U=IxR i.e. the voltage drop across the shunt will be 0.5 Volts. Now you need a suitable voltage gauge. Where it reads 0.5V you make your own reading 50 Amps instead.

[Charger RT]

That regulator should be fine mine is smaller and does not look stock but has worked well for the last 4 years. I picked mine up at the local parts store.

You do have a bulkhead connector issue. Nacho has made a few threads on a parallel circuit it basicly is to repair that damage and run two more wires in to the dash and parallel the oem circuit. (there is one more wire in that connector you need to look at.) I prefer to fix the two wires and add an 8 gauge wire from the alternator back to the battery. It makes the amp meter not work but does stops the current that charges the battery coming from the alternator from going through the bulkhead connector. That would allow the 2 wires going through the firewall to split the load to run the car.

Another issue is with a 60 amp or larger alternator the amp meter was not designed for that load. There is a thread with a dash that had the amp meter replaced with a good looking volt meter.
Tim

[sebarger]

Thanks for all your advice guys.

I thought I would post the latest update for posterity. It turns out that the source of all my woes...wait for it...was a miserable 25 cent washer which had wedged itself behind the live terminal of the alternator and the block shorting out the green lead from the regulator...(sigh). It was one of the washers that held the alternator on and probably fell when the last guy swapped out the alternator...

Since everything was fried, upgraded to a new dual lead 65-100 amp alternator, new voltage regulator, 4 prong ballast resistor, new engine wiring harness from Year One, did the amp meter bypass and added a couple of headlight relays for good measure. Now the car not only runs stronger (clearly better spark) but the headlights are bright too :-)

I am still searching for someone that will sell a replacement voltmeter gauge that looks like the original amp meter to complete the swap. I e-mailed Redline but haven't heard anything back...

[Nacho-RT74]

if you have the time an patiente, read this AND links posted there:

http://www.dodgecharger.com/forum/index.php/topic,62772.0.html

will learn a lot on how works and how to read an ammeter. Also how to save from mistakes made allong the years ( including factory mistakes )

5 or 6 years since I did this, on my DAILY car, with AC... still not a problem and I have all my stock parts working

( madelectrical info is wrong in several statements )

[HeavyFuel]

Nacho....what do you think of this technique (recommended by E-booger) that is designed to keep the bulk of the current out of the dash?

"Simply connect the alternator output stud, via some serious gauge wire (matched to your alternator's output specs) to the battery stud on the starter relay. But be absolutely sure you splice in an appropriate length of fusible-link wire into this new conductor!

Here's what gauges to shoot for:
Alternator output rating   Wire gauge   Fusible Link
Under 50 Ampere                        12                       16
50-65 A.                                    10                       14
85 A.                                         8                          12
100 - 120 A.                            6                     10

With this done, the bulk of the charging system current will no longer flow through the firewall connector - or the ammeter. Obviously, the ammeter will no longer be accurate. The plan here is a simple accessory voltmeter, which should have its positive (+) side wired (with practically any gauge wire) to any ignition-switched 12-volt point, and the negative (-) side to ground."

[b5blue]

  The gauge as a weak point is somewhat of a miss-identifyed issue. It only takes a beating trying to maintain a large current to charge a battery that is more than just slightly discharged. At any point in the cars past if someone tried to charge a dead or mostly dead battery the cooking has started. Cars are never meant to recharge dead batteries, by design they are engineered to maintain a battery from loss of charge from starting the engine, and run accessory's.
  If you address THE REASON the battery is discharged you'll not have problems if your harness is in good condition.
  Weak idle alternator output is by far the biggest issue. At idle if your draining the battery (Say at a stop light) the gauge reads - and the car is running off at least some of the battery draining it's charge. Then you increase RPMs and now the Alt. amps increase to meet load AND recharge the battery. Repeat this cycle over and over and heat builds up faster than it can cool back down and "Oh that stupid ALT gauge is the problem" myth appears to they who know no better.
  Nacho's upgrades will work just fine and improve efficiency by greatly reducing the load that the original harness and switches must handle. If you still have low Alt. output at idle, you still have a problem. (That bypassing the gauge will NOT fix, you only mask the true problem.)

[resq302]

sad thing is I think every Mopar I have ever seen or been in at night time with the headlights on have this problem at idle.

[b5blue]

My 120amp Denso fixed that for me. (Plus I serviced my harness, cleaning and checking things.)