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Charging issue or alternator?

flamesoldier

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Is my alternator shot? The battery terminal on alternator running is 14.03V, the blue field is 12.58V, the voltage regulator is brand new and grounded good. The battery is only charging at 12.23V. If i remove the lesser voltage field terminal and jump it to battery negative she charges right up at 13.8V. The connections to the ammeter are tight and clean. If the alternator taking a dump?
 

Chryco Psycho

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If the Alt is putting out 14 + volts the alt should be working but the battery should read the same so you could have too much load , with electric fans , fuel pump etc . or you could have resistance in th circuit ,corrosion / bad connects etc . The regulator could also be bad , new means nothing , probably chinese made , you ground the field & it charges properly it seems to be a bad reg .
 

Challenger RTA

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Really long story short. Have a number of cars for a number of reasons. Car 1 had a charging problem. About an hour of driving or just sitting there running. The alt light would come on. Checked at battery and alt it was charging. Cleaned all chassis grounds inside and out. Have the same kind of car 2 swapped alt. Never had a problem with car 2 alt and the alt that I swapped to it. And to this day still don't have a problem with car 2.
Completely removed the wiring harness from the dash and under the hood. Check and cleaned fuse boxes and connections. And yes the computer that controls everything. That can be task in today's cars.
So I put my brain in Rocket Scientist mode and figured it out.
Think simple. And I did. I stared at the alt the mounting bolt were the problem. Took ever one out, cleaned them and the holes too. Voila! Fixed!
 

flamesoldier

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Wandering if this 9.5 resistance is my issue voltage regulator shouldnt it be 1.75 ?
Really long story short. Have a number of cars for a number of reasons. Car 1 had a charging problem. About an hour of driving or just sitting there running. The alt light would come on. Checked at battery and alt it was charging. Cleaned all chassis grounds inside and out. Have the same kind of car 2 swapped alt. Never had a problem with car 2 alt and the alt that I swapped to it. And to this day still don't have a problem with car 2.
Completely removed the wiring harness from the dash and under the hood. Check and cleaned fuse boxes and connections. And yes the computer that controls everything. That can be task in today's cars.
So I put my brain in Rocket Scientist mode and figured it out.
Think simple. And I did. I stared at the alt the mounting bolt were the problem. Took ever one out, cleaned them and the holes too. Voila! Fixed!

IMG_1749.jpeg
 

Challenger RTA

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This is how to do a test on the car. The point I'm making is I think it is a ground. The mounting bolts for the alternator are the ground. Check the neg cable on the motor and chassis ground. The voltage regulator when bad most of the time,will read open or a dead short.
 

pschlosser

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These are great, to start with the battery ground is on aluminum intake manifold which im sure isnt great

That's how it is on my car. I think this is where it's supposed to be grounded, on the front-most driver-side intake manifold bolt. There is a webbed strap near the starter that then grounds the chassis to the engine.
 

flamesoldier

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Update im completely shot out in the dark and this is crazy and only thing im to believe is something inside alternator is not connecting the dots maybe

Low to no charge issue. Thoughts issue with alternator? Or something im missing everything else below tested out

❌RUNNING battery at 12.4 not charging at 13.5-14. If I remove voltage regulator connection charge drops even more to 11.9.
❌ Increasing throttle couple thousand RPMs only moved charge to 12.6 at battery.

✅KEY OFF Alternator BATTERY terminal matches battery
✅KEY ON Alternator 1 point drop normal loss
✅KEY ON-Alternator field terminal blue 12.58
✅RUNNING Alternator BATTERY terminal 14.03

✅Alternator charges with lower charge field wire jump test (simulating green wire terminal)

KEY OFF WIRE HEALTH TESTING AT 200 ohms
✅Green field wire from voltage regulator side connector head to alternator side field terminal connector 00.8 ohms resistance
✅Blue field wire from connector head to field terminal connector 00.8 ohms resistance
✅Alternator battery charge wire (black) to bulk head (firewall side)00.6 ohms
✅Bulk head charge wire (firewall side)to starter relay (red)1.4 ohms resistance
✅Alternator ground terminal post wire to cylinder head 00.9 ohms
✅Green field wire with key on sparked when connecting jumper to either the voltage regulator connector side or alternator field connector side.

Interior bulk head side
✅Black charge wire to ammeter from ammeter terminal to bulk head connection 00.7ohms
✅Red charge wire to ammeter from ammeter terminal to bulk head connection 00.8ohms
✅Key on - Both sides red and black wires going into ammeter had 1 point volt drop. Matches the battery terminal on the alternator.
 

Challenger RTA

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The bulkhead connectors are more than likely the issue. Clean them up and check again. Splice 1 is never the issue unless someone messed with it. You can feed it some other way. through the washer foot pump grommet. But use the fusible link.

1732933793398.png
 

Challenger RTA

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I had to look but I found it. This is what you should do.
By all means, by-pass the bulkhead connection for the charging system wiring. In the second shot above you can see the 8-gauge (red & black) charging system bypass wiring. I will un-wrap a new M&H engine harness and replace the 12ga alternator output wire with an 8ga, routed directly the ammeter via a added firewall grommet. Yes, on b-body fleet production with 65 amp alts, the factory did the same thing.View attachment 96599
 

Challenger RTA

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This too. Myself I would only do the red power and the black acc feed. The rest are low current. But could still cause a problem. This is a good fix from 72RoadRunnerGTX.
Yea, all ignition related dash harness wiring went to 12 gauge by ’72, I’ve seen some later replacement switches where a couple runs were 10 gauge on the switch side. Funny, they never really addressed the real weak spot, the Molex terminations that are way current under-rated for that application. Many Molex heat related terminal failures at that connection since day one. I replace the ignition switch Molex with Anderson PowerPoles on my builds.View attachment 96597View attachment 96598
 

pschlosser

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More free opinion:

Update im completely shot out in the dark and this is crazy and only thing im to believe is something inside alternator is not connecting the dots maybe

I may be a skilled over-thinker, and often get bitten by my own anxiety and curiosity. Be careful not to over think what you're seeing, and get yourself all spun out. We may not have an answer for every one of your questions. Some, perhaps most, of them don't need to be researched and answered.

Low to no charge issue. Thoughts issue with alternator? Or something im missing everything else below tested out

The alternator contains 3 or more diodes. These can go bad with age, one by one, or even fail when pulling the battery terminal while the engine is running. As each diode goes, the output voltage of the alternator gets lower and lower. I've had the experience of pulling a low-performing alternator, presumably with only one working diode, take it down the to parts store for testing, only to be told it's functioning fine.

If you are seeing 14+ volts anytime-anywhere, then I suggest your alternator is NOT underperforming.

❌RUNNING battery at 12.4 not charging at 13.5-14. If I remove voltage regulator connection charge drops even more to 11.9.
❌ Increasing throttle couple thousand RPMs only moved charge to 12.6 at battery.

Careful running a partial system with the engine running, and/or disconnecting things while the alternator is outputting voltage. You can ruin/break your voltage regulator or alternator doing this.

Don't waste your time taking measurements with the engine at idle. Few alternators from this era can output decent voltage under 1000 RPM. But your target of 2000 RPM is a good place to take measurements.

✅KEY OFF Alternator BATTERY terminal matches battery
✅KEY ON Alternator 1 point drop normal loss
✅KEY ON-Alternator field terminal blue 12.58
✅RUNNING Alternator BATTERY terminal 14.03

If you're seeing 14.03 volts output from the alternator, I'm going on record that it's performing fine. If you have a charging issue, it's elsewhere.

✅Alternator charges with lower charge field wire jump test (simulating green wire terminal)

KEY OFF WIRE HEALTH TESTING AT 200 ohms
✅Green field wire from voltage regulator side connector head to alternator side field terminal connector 00.8 ohms resistance
✅Blue field wire from connector head to field terminal connector 00.8 ohms resistance
✅Alternator battery charge wire (black) to bulk head (firewall side)00.6 ohms
✅Bulk head charge wire (firewall side)to starter relay (red)1.4 ohms resistance
✅Alternator ground terminal post wire to cylinder head 00.9 ohms
✅Green field wire with key on sparked when connecting jumper to either the voltage regulator connector side or alternator field connector side.

Interior bulk head side
✅Black charge wire to ammeter from ammeter terminal to bulk head connection 00.7ohms
✅Red charge wire to ammeter from ammeter terminal to bulk head connection 00.8ohms
✅Key on - Both sides red and black wires going into ammeter had 1 point volt drop. Matches the battery terminal on the alternator.

I don't believe the resistance of many of these wires/circuits are documented by the service manual. Asking someone to go "buzz out" their charging system to document these numbers may be academic and afford little value to others. Many of us are motivated to go test something unusual, only when it seems of value to the community.

One task I have done on several vintage mopars, is cleaning connections. Take your time. Be thorough. This is a hobby for many, and it's supposed to be fun. For some of us, it falls within our retirement, and few of us are in a hurry.

Cleaning every connection in the engine compartment will pay for itself years down the road.

Cleaning procedure:
  • disconnect a given connection
  • observe the connection for rust or corrosion
  • clean using acetone, a degreaser, or whatever seems appropriate
  • (optional) grease (to protect further oxidation) using clear silicon grease.
  • replace connection
In your case, I would clean every connection in the engine compartment. The includes the bulk-head connectors, and every other crimp and bolted connection I could find.

After doing all of that, if you still have charging issues, they may be pretty easy to find, because the system should be functioning precisely as it did when it rolled off the assembly line. It's remotely possible you may need to repeat the cleaning procedure inside the passenger compartment, focussing on those connections from the bulkhead to the instrument panel.

Having said all this, for those reading this later to resolve their issues, I suspect your voltage regulator is the problem. The Chinese are still trying to catch up to US-quality-made semiconductors, and if you have a newish voltage regulator, that may be the problem.
 

Challenger RTA

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pschlosser

Has some valid points.
This a process of elimination. No matter where you read voltage. You are reading to ground! If there are bad connections anywhere ground or power feed connections. You will not get the correct readings. clean all connections and grounds.
A point about electrical and electronic components. They range in which they function. Electrical components have a tolerance of about 10%. Electronic components have a tolerance of 5% or less. A few might know what this is. NPN, PNP.
So I put my brain in Rocket Scientist mode and figured it out.
Think simple. And I did. I stared at the alt the mounting bolt were the problem.
Case and point and an other thing. I was working with a operator that was running an excavator. They are mechanically inclined. For they have to be running equipment. He had a problem with his car starting. Replaced battery, starter,solenoid and battery cable to starter. This went on for a few weeks. When he first ask me. I told it was more than likely battery cables. He said they look good and clean. So one more time I told him it was the battery cables. I explained to him the cables corrode about an inch in and it can't be seen. He had his mechanic change the ground. Viola! The thing about grounds their like black holes. You want to stay away from them. They are so miss understood and ignored. They are pat of the equation!


Grounds count there is one but many! I would eliminate this first.
 

72RoadRunnerGTX

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These are my testing results possible the main splice or bulk head connector
Maybe it has been mentioned here already I didn’t see. The only way to do voltage drop tests accurately is with some current flowing. Need to take these measurements with the engine running and some loads turned on. Static or engine off results will not necessarily reflect correct high resistance points. That said, the 1.3v drop number at that bulkhead battery feed Packard terminal jumps out as a big problem. As mentioned, do yourself a favor and just by-pass those two bulkhead connector Packard’s in the charge path. The weakest link in the original charging circuit.
Related video on how to take voltage drop measurements.
 
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