Charging issue for the electrical guru's

[YellowThumper]

First the problem.
I am having issues with my Challenger not charging at proper voltages consistantly. Sometimes all is ok and sometimes it is pegging 16v. This is with a new v regulator. I had what I would call similar issues with previous v reg that was probably 10 years old. But it was on the opposite side of the spectrum. Too low or only up to 12.5ish volts.

Simplistic question first before what wI'll be a lengthy account of what I have modified.

Is it possible that the Alternator is not "following" what the regulator is trying to regulate?

Ok here is the setup...
Yes Ammeter is bypassed.
Battery is relocated to trunk.
Grounded there. This is a California car. Rust is no issue.
Engine has factory strap to firewall.
Also have normal battery size ground wire from head to frame where battery use to be located.
Positive comes from battery to engine compartment to lone bulkhead connection with alt charge wire and starter connected to it.
LA 360 but I have adapted Magnum front accessories. Alt included. This is wired using factory Challenger regulator.
I am using aftermarket volt gauge. This I believe to be reading correct as it resets to 12v with key on and car not running.

Any help would be appreciated.

Thanks.
Mike

[GoodysGotaCuda]

The alternator is likely not the problem. I personally have only seen them charge, or not charge. Voltage problems are typically on the control side.

How is the ground for the voltage regulator? The case must be well grounded for it to do its job.

The regulator has 12v going to it during key on. If there is a voltage drop in that wire, it will cause it to see a "lower than system" voltage, and cause an overcharge condition. In the past I have used a relay triggered by the factory 12v wire to ensure I had a crystal clear "system reference voltage" being sent to the VR.

Lastly, I would undoubtedly question the "new" voltage regulator. Especially if it's from any common parts house. They are pretty notoriously low quality.


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[TelisSE440]

Hi YellowThumper, i will try to keep it short. It seems to me that you have high resistance somewhere in your wiring but we have to prove it first. The Voltage Regulator has two studs which the black plug attaches (the blue and green wire). Turn on the ignition (don't start the engine), disconnect the plug and measure the voltage of the blue wire with a voltmeter. Then measure the voltage of the battery, over 0.3v difference indicates high resistance and this would be the problem. I would check this first, if difference is lower then please tell so we could check the rest.

[Jim AAR]

I had an overcharge problem with an Electronic Voltage Regulator in the 90's when I was on the highway coming home from the lake and it ended up blowing the caps off my battery and making a mess of my newly painted engine compartment, creating black dots and bubbling of the paint on my inner fenders and pretty much everywhere else it landed and I even washed it off as soon as I got back into the city within an hour. What a piss off. 

The Electronic VR's from that period were notoriously garbage, that;s why I just ended up putting on a regular VR and not an Electronic one, the old style Non-Electronic ones rarely ever failed.

[YellowThumper]

Thanks, and I will check v drop first.
I will add that the engine portion of the harness has been remade by me. Plug and a short length of its wire to v reg is still old one but wiring outward is all new.

Car has duplicate secondary system being added for MS3X and all the accompanying sensors and the like for full distributorless with ls coils. This is also all wired in but remains off line until I get these spikes addressed.

Final goal is to end up rendering the old wiring obsolete. Obviously not there yet...

Thanks again

[dodj]

I would start with the VR myself. First, like Goody, I would check the grounding. I like to use 'star' washers to ensure you 'bite' into the body metal. In order to make sure the VR 'sees' the correct voltage all connections need to be clean. So inspect your B/H and column connectors. Clean if needed and coat with non conductive (di-electric) grease to help seal out future corrosion.
If no change in your symptoms, I would buy another VR.

[Roadman]

           I always use rivet nuts on the voltage regulator, plus a ground wire to the block.   

[GoodysGotaCuda]

I've had good luck with the eBay part number C8313 voltage regulator running my 150a Hemi alternator.

[YellowThumper]

I've had good luck with the eBay part number C8313 voltage regulator running my 150a Hemi alternator.

Thanks, we will see after I check off the other noted items. I have plans to upgrade to higher amp one. Another  Magnum replacement. Just also don't want to throw more amps at it until this is addressed. Hence first question if alt could be malfunctioning.

Just because we all like pics. Here is the menagerie I have going. All FI hardware is on less throttle body but car remains on carb and standard ignition. Eventually I will stop threatening to fire up my thread and do it here...

[Chryco Psycho]

With battery in trunk installs I usually run the ground cable back to the trans at least so you have battery ground connected to the engine , not saying this is the problem but it helps with the starter as it is the highest load .
What does the battery voltage measure ?
Other than that I agree that regulators & or ground is the problem .
Positive battery cable should run to the starter first using the 10 ga wire up to the start relay on the inner fender .
Alt Can be a problem if a diode is bad but it will not fluctuate , generally it is charging properly or over charging

[dodj]

with battery in trunk installs I usually run the ground cable back to the trans at least so you have battery ground connected tot he engine . not saying this is the problem but it helps with the starter as it is the highest load .

Running a -ve battery wire up to the trans or engine is a good idea with a trunk mounted battery. It doesn't necessarily have to be as large a gauge as the +ve due to the body also being a -ve conductor, but it should be at least a 4 gauge.

[73_Cuda_4_Me]

I had similar issues with mine, and found the connector to be the issue. Had to clean inside barrels on connector with some 600 grit, then tightened the barrels up using small needle nose pliers, and applied some dielectric grease to the pins on the VR...

I could make my alternator load/unload just barely wiggling the connector slightly while idling...

[73440]

I had similar issues with mine, and found the connector to be the issue. Had to clean inside barrels on connector with some 600 grit, then tightened the barrels up using small needle nose pliers, and applied some dielectric grease to the pins on the VR...

I could make my alternator load/unload just barely wiggling the connector slightly while idling...

I have looked at buying a replacement connector, will try this first.
Having charging issues also.

[YellowThumper]

Hi YellowThumper, i will try to keep it short. It seems to me that you have high resistance somewhere in your wiring but we have to prove it first. The Voltage Regulator has two studs which the black plug attaches (the blue and green wire). Turn on the ignition (don't start the engine), disconnect the plug and measure the voltage of the blue wire with a voltmeter. Then measure the voltage of the battery, over 0.3v difference indicates high resistance and this would be the problem. I would check this first, if difference is lower then please tell so we could check the rest.

Life has been busy but finally got around to working on my charging issue. Replaced the v regulator yet again. Fortunately I now have 2 that are doing the same thing consistantly. So I can believe them over the sporadic others. Bad news is I am steadily charging close to 16v.
So based on TelisSE440 and Goodies suggestion I checked the voltage on blue connector wire. There is a difference of about 1.2 volts compared to battery. I also checked my power wire to ground up front. This matches battery direct as it should. Now to do some tracing it backwards. I assume it comes thru the bulkhead. If necessary I will then wire in a dedicated relay for it.
Anyone have a quick link or diagram of this area of wiring?
74 Challenger. Thanks.
I sooo want to drive this again...

[crackedback]

Size of charge wire to rear of car? 

Often sorely undersized!