Overcharging Help needed (74 scamp)

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70DUSTER/74SCAMP

70DUSTER/74SCAMP

Sold the scamp ....still got the duster tho
Joined
Jul 30, 2020
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Location
West Central Indiana
S.O.S. ok folks here we go. so i have a 74 scamp with a 318. i have a new napa alternator and and a new battery and a new volatage regulator. yesterday i put a new voltage regulator on and when i hook it all up im getting 15 plus volts inside the car and at fuse panel mean while only like 12.38 volts at the battery . when i unplug the new external regulator it drops back down to 11 plus volts in the car. honestly at a loss here .i have a dual field alternator. one goes to to the regulator the other i have tied in to the igniton wire on the regulator and bypassed all the way to the ballast resistor for key on run hot. i know im a dumb redneck but at a loss and about to set this car on fire haha. very frustrating any help would be greatly appreciated. just got the engine running awesome and running good now dealing with this issue of over charging and battery not charging . just frustrating. so thats where im at folks thanks for looking .
 
Throw in your old regulator and see if it changes. Some times new parts won't function right.
 
Had the same issue a couple years ago. Try charging your battery. That was my problem. By the way it was on a 75 Scamp 318 all original no cut up wires.
 
Maybe this might help ?

Electronic ignition dual ballast.jpg
 
moparker said:
Had the same issue a couple years ago. Try charging your battery. That was my problem. By the way it was on a 75 Scamp 318 all original no cut up wires.
Click to expand...
Maybe new battery will charge up and voltage will drop when satisfied.
 
But you shouldn't use your alternator to charge your battery. Put it on a charger and it will probably be ok.
 
Yes. Do it with a battery charger. An old one preferbly.
 
moparker said:
Had the same issue a couple years ago. Try charging your battery. That was my problem. By the way it was on a 75 Scamp 318 all original no cut up wires.
Click to expand...
Analog, not digital. They do a better deeper charge.
 
70DUSTER/74SCAMP said:
i know im a dumb redneck but at a loss nd about to set this car on fire haha.
Click to expand...
The good news is A. You're not about to set the car on fire with things you've done so far.
B. A lot of people have no clue about this - including a lot of city slickers... ;)

So all of these are NEW.
Battery
Voltage regulator
Alternator.

It is possible that the battery is not fully charged, but that's not the major problem. At least not yet. If you keep running the car on battery, then yes, it will be best to put it on charger so the alternator doesn't have to do a major charging of the battery.

Lets get to the problem.
70DUSTER/74SCAMP said:
when i hook it all up im getting 15 plus volts inside the car and at fuse panel mean while only like 12.38 volts at the battery .
Click to expand...
If you are measuring at the battery when the engine is running, then you are correct the battery isn't connected to the alternator output.

a. What does the ammeter show? This is what actually shows the battery charging.
b. We commonly say charging to describe the alternator output. However for a situation like this its really important to seperate alternator output from battery charging. The car equipment is at 15 V so the alternator is clearly producing power.

70DUSTER/74SCAMP said:
when i unplug the new external regulator it drops back down to 11 plus volts in the car.
Click to expand...
And when the VR is unlpugged, its not.
11 V seems low for just running an engine. Either there is a resistance in the line, or the battery is low.
(or there is some modification you haven't mentioned)


70DUSTER/74SCAMP said:
i have a dual field alternator. one goes to to the regulator the other i have tied in to the igniton wire on the regulator
Click to expand...
from your description this is correct.
70DUSTER/74SCAMP said:
bypassed all the way to the ballast resistor for key on run hot
Click to expand...

Not sure what you did here. Lets just check everything over
The alternator OUTPUT WIRE goes from the stud to the main splice.
The Regulator Sense Wire comes from the 'ignition 1' (aka run) circuit to the top corner pin on the regulator.
One Field Wire also comes from the 'ignition 1' (aka run) circuit.
The Other Field wire goes to the regulator corner pin.
For how it works, see "isolated field" alternator this post Identifying Chrysler Alternators (1960-1976)
 
Standard wiring should look something like this.
upload_2021-3-26_9-43-4.png


Whether J2, J2A, J2B, and J2C are joined at single welded splice or some otehr way isn't important. They just need to be all connected together.
 
I do not have J2C joined .what i did is run a jumper wire from the top side of my ballast resistor blue with yellow stripe all the way to the blue wire coming from one field side to the ign blue on voltage regulator so that it has key on power that way . the key on blue wire or J2C I could not find or have not seen it yet. maybe i did it all wrong?


Whether J2, J2A, J2B, and J2C are joined at single welded splice or some otehr way isn't important. They just need to be all connected together.[/QUOTE]
 
70DUSTER/74SCAMP said:
I do not have J2C joined .what i did is run a jumper wire from the top side of my ballast resistor blue with yellow stripe all the way to the blue wire coming from one field side to the ign blue on voltage regulator so that it has key on power that way . the key on blue wire or J2C I could not find or have not seen it yet. maybe i did it all wrong?


Whether J2, J2A, J2B, and J2C are joined at single welded splice or some otehr way isn't important. They just need to be all connected together.
Click to expand...
[/QUOTE]
 
I will check the exact voltages when i get home at everything with my volt meter. stumbled upon a bad conncection at the bulk head for the main hot wire that comes in to the car its hanging on by a thread of wire so going to drill a hole in the bulk head connector and feed some new 10-12 thru the hole . if u jiggle it now the car jut dies( previous hack job by other owners) . Thank u all for the help hopefully i can get this sorted out based on wiring diagrams i have it correct so i think i just couldnt find the blue wire from the ballast around the intake area i needed to make it right right so i thought i could jump onto that wire at the ballast and run it around to the ignition side of the VR and splice those to to the other field side on the alernator.
 
Sounds like J2C is joined to the others. just through a different path.
The blue with yellow trace is same side of the resistors.
Here I redrew it so there's no crossing lines.
upload_2021-3-26_10-41-54.png


Only possible issue is the resistance at each additional junctions can add up. This could explain higher voltage output, but not the lower voltage at the battery.

What's the ammeter show?
 
15.65 V At the fuse panel when running . 12.38 at battery when running . not running battery around same and 11.48 volts at fuse panel
 
70DUSTER/74SCAMP said:
stumbled upon a bad conncection at the bulk head for the main hot wire that comes in to the car its hanging on by a thread of wire so going to drill a hole in the bulk head connector and feed some new 10-12 thru the hole . if u jiggle it now the car jut dies( previous hack job by other owners)
Click to expand...

I think you have most of the concept correct.

A bad link in the battery line could explain what you see.

Don't drill! OK. Actually maybe drill, but not yet! ;)
That's probably the fusible link. Replace that. It's the only protection against an accidental grounding in main circuits. Say someone accidentally touches the alternator output post to ground with a wrench. Or - and this happens - the output circuit grounds (loose, damaged or badly assembled alternator). The fusible link will minimize the damage and prevent a fire.

So fix that. You can buy factory looking replacements that plug in, snag one from another harness, or make one up from the parts storeif you have the terminals and crimpers.

Drilling I'll come back to...
 
Make sure the new VR is fully grounded.

Had the same issue with my LA 360 on my 69. Had to run a ground from the mounting screw to the firewall..

Bruce
 
THIS SOUND LIKE MY FAVORITE PROBLEM which is very simple in nature, sometimes difficult to grasp and usually simple to fix

HERE IT IS

VOLTAGE DROP in the HARNESS AND SWITCH AND TERMINALS along the path from the battery to the VR and that also includes the GROUND side of the circuit

HOW TO troubleshoot and fix:

1....Turn the key to "run" with engine stopped. Stab one meter probe into the top of the POS batter POST. Connect the remaining probe as close as you can get to the VR IGN terminal (blue). If you can't do better, connect to the "key" side of the ballast. You are hoping to read very little the lower the better. Anything over .3V (3/10 of one volt) you need to investigate and fix

If you don't quite understand this, measure the two voltages to ground. IE with key "in run" measure battery POS voltage to engine block, "note" and read key side of ballast to engine block, and subtract the readings. Same reading as above^^

One way to fix voltage drop on the hot side is to use a relay to feed the ballast resistor and VR. Electrically cut the (normally) dark blue "run" line coming out of the bulkhead. Use the bulkhead end to trigger a relay. Feed the relay off the starter relay "stud" through a large fuse or breaker. Connect the engine bay end of the wire you cut to the siwtched contact of the relay.

2...GROUND. With engine running on fast idle to simulate "low to medium cruise" RPM, make reading first with all accessories off, and again with lights, heater, etc running. Stab one probe into the battery NEG post and the other into the metal mounting flange of the VR. You are hoping, again, for a very low reading, ZERO volts is perfect. If you read ANYTHING improve the grounding from battery NEG to the body.

Remove VR and scrape around mounting bolt holes, remount with star lock washers. Consider adding an eyele-to-eyelet "starter" cable from the driver side cylinder head to the firewall, there are bolt holes on the rear of a v8 head, and the master cylinder studs are a good point on the firewall. You are on your own on an slant 6
 
WHY THIS HAPPENS

When there is voltage drop either in the hot harness or the ground, the VR is NOT seeing the "same as" battery voltage. When the voltage reg. is warmed up and is properly regulating to 14V nominal AT IT's TERMINALS, IE it's ground and it's IGN terminal, these voltages ARE NOT what the battery is seeing because of the harness voltage drop. The load on the harness that is the igntion system, the VR/ field circuit and whatever else is on the "run" line PULLS DOWN the voltage as it drops through the harness, so the VR "ramps" the voltage back up..........and at the "other end" this ramped up voltage is what the battery "sees."

A DIFFERENT WAY to check this and to understand this is start and warm the engine and get the battery "normalized" after starting with the thing on fast idle. Measure battery voltage to engine block. "Let's say" it's 15.5V TOO HIGH!!!

Now measure the "key side" of the ballast resistor to engine block. 14V!!!! WTF!!! NORMAL!!!! Caused by voltage drop!!! The VR is JUST FINE!!! It is regulating at 14V!!! But to get "that 14V to that point in the harness" so to speak, it has to travel from the battery, through the harness--and through the voltage drop-- to the VR connection at the ballast. And now it has DROPPED because of the resistance in the harness

WHAT IS THIS resistance???

Usually, bad, corroded terminals ANYWHERE in the path. From starter relay, through fuse link, the BIG RED wire going through the bulkhead connector..........goes to ammeter, might be a small amount there at the ammeter too----goes to the WELDED SPLICE in the black ammeter wire, branches off to the IGNITION SWTICH CONNECTOR can be drop right here at the connector.........AND THROUGH THE SWITCH ........and there is likely some drop there in the switch contacts, then BACK OUT THROUGH THE SWITCH CONNECTOR on the "dark blue" IGN1 "run" wire so more drop through the connector terminals.........now BACK OUT THROUGH THE BULKHEAD CONNECTOR on the dark blue "run" so even more drop through the bulkhead connector and finally to one end of the ballast and near there somewhere / branches off to the VR and can even be some drop at the VR IGN terminal
 
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70DUSTER/74SCAMP said:
15.65 V At the fuse panel when running
Click to expand...
This probably has something to do with the regulator wiring. It has no idea the output is 15.8 Volts. it only knows what it senses. So if there are voltage drops between the output and the regulator's sense terminal, this causes it to try to bring the voltage up unit it sees something around 14.
If the regulator is sensing 13 Volts at its top terminal, its going to let more current through the rotor.

The 12.4 Volts at the battery with 15.6 at the fuse box.
I keep asking about the ammeter reading because this will reveal what is going on.
With only voltage reading, we can only guess.

So here's my guess. The battery is a bit low. Even if its normal low after starting.
At fast idle the alternator output is offering power around 15.8 Volts
The battery sees that and tries to draw 10 to 20 amps but enounters lots of resistance.
Some current gets through. Dunno how much, maybe 10 amps, maybe 5 amps. Whatever it is, the resistance is high enough that the voltage on the other side of the resistance is only 12.4 Volts.
upload_2021-3-26_11-9-22.png


Think of current like a river or stream. It divides at junctions to go to each way there is a path back to ground.
But it loses energy when it goes through resistance. That's the voltage drop. Its like the diffence between the power in the water coming over the top of a dam and the same water when its at the bottom.
 
Sorry guys you are doing a dance here THIS IS ALWAYS ROOT CAUSED BY HARNESS VOLTAGE DROP. It is almost NEVER caused by a bad VR and is SELDOM but sometimes caused by an old / sulfated / dead battery
 
Mattax said:
Drilling I'll come back to..
Click to expand...
Since its already been hacked up a bit.
If you want to take the alternator and/or the battery feeds through a grommet in the bulkhead copy what the factory did. There's already indents for the grommet locations in the firewall.

To me the simplest version to copy is the one that only needs one fusible link.
Its the one the used for defroster grid equpped cars.
How rare is electric rear defrost?

A little more work perhaps is to use this approach from the '73 Dodge FSM
Ignore the field and VR connections as they are specific to the Leece Neville alternator.
It needs two fusible links. A 10 ga to protect the 6 ga heavy wiring, and a 16 ga to protect the 12 ga wiring.
upload_2020-3-29_16-18-37-png.png




There's some other variations on the same theme. They all work. Some are easier to retrofit than others or better meet specific requirements.
A couple pics from what I did on my '67 here Firewall pass through
 
Any difference between the 15.8 Volts at the fusebox and the assumed 14 something Volts at the regulator would be resistance in that curent path..
The connector in the column, the key switch itself, the bulkhead connector are all areas to check.
upload_2021-3-26_11-54-18.png
 
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