Been dealing with poor charging at idle with my stock and a new rebuilt alternator on my 67 coronet. Round back with single field?

Seems as if it didn't act up much the first couple of years ( 2500 miles) I drove it after the restoration, now nothing seems to help..

I have had 3 different voltage regulators and now a rebuilt alternator. The new alternator seems to charge and act great except at idle especially with the lights on.. the lights dim at idle, blink with the turn signals etc. If I rev it up maybe 500 rpm it makes a huge difference. The volt meter will show decharge almost to the bottom of the scale with the lights on at idle.
My amp gauge has been converted ( redline ) to a volt meter, so no wires there anymore, and all wiring was new 4 years ago..

I am going to try cleaning and installing some extra grounds ( to the VR, and the lights) where I think it might help.
Has anyone tried the high output alternators from powermaster or Quality power Auto?? There claims are more amps at idle than my stock one puts out at speed??

what has anyone else done to solve there charging problems??

so mopar alts are just bad at idle.
however, you can up your amps by just going to a square back alt.
ground one field wire and you can continue to use your stock voltage reg with no other wiring changes.
These are 50 dollar alt from any parts house.

putting your lights on relays, putting as solid wire through instead of the bulkhead connectors for main power might also help.

or you can step up to several of the higher dollar ones as you listed.
BUT I prefer to use something more easily access and replacable from the parts house.
like the early magnum ones, or the toyota ones they replace the pulley from.

First would be to clean all connections/terminals which sounds like you have done. An electronic reg might help some & since you have replaced em I'm assuming you have an electronic one in there right now. The 85 M body 78 amp alt I believe is about the best stock alt. You could ground 1 alt field wire if you still have the OE 68 1 field wire circuit to use that alt. No actual experience with it but I've read several good reports on the Denso conversion to especially get better charging at idle. iirc you need the chebby 10 dollar chrome bracket & likely some spacers but that's no big deal but I'd wait for others to confirm/add some more info. If you have the largest crank pulley that will give you the most alt speed & might require a smaller water pump pulley to allow the crank pulley to fit & that gives you a side bennie of more water flow & if you run an anticav plate there's no danger of high RPM pump cavitation from the pump spinning too fast. If you have electrical add ons then relaying them to the alt may help & does keep that current out of the bulkhead & feeds em right from the source (the alt)

The easiest option would be to go with the later style squareback alternator from a late 80's Mopar. They are rated at 78 amps at speed and put out roughly 40-45 amps at idle. Even an earlier stlye square back from a 70's model will be rated at 60 amps at speed. You can get the later style alt by asking for the alternator from a 87 Diplomat. I have one I got from O'Reilley's here...cost me $55.

This should bolt to your brackets but you will want to go with a solid state VR and ditch the mechanical one you probably have now. You can buy the triangular VR plug from the parts stores or RockAuto and make/adapt your harness to work with it by making it dual field. You could use the old style VR and just ground one field wire but I would go to the newer style reg. It offers much 'cleaner' voltage with less noise.

This should be more than enough juice for a car with OEM-type loads. If you are adding electric fans/pumps/big stereo amps etc, you will need to go to a 100 amp or higher most likely.

Adding relays won't help a low charging situation. In fact they will exacerbate the issue. Relays are used to eliminate voltage drops on circuits like headlights so they can shine brighter (and thus draw more current) as the relay gives the current a more direct path.

Only way to get more amps is to upgrade the alternator.

Here is a picture of the dual field charging circuit. Just pay attention to the VR to alt wiring. Blue wire is battery voltage (keyed from ign switch) and the green wire is the field wire that allows the VR to 'control' the alternator's output. Picture credit to Nacho!

i know it's a common problem at idle but i still gotta ask - are you sure your belt isn't just slipping too much?

Check the field wire at the alternator terminal end, I had one that had about three strands left and it didn't work worth a hoot Worst thing to find is there okay and not bad Good luck, let us know what you find

Agree the later squareback is better and a bolt in as posted. In addition to checking/adding grounds and VR wires, suggest you check/clean the bulkhead connector. Full alternator output goes through those little 1/4" connectors and its a lot. Also check/clean connections at the ammeter. These are subject to heat also due to high loads. If all is in good shape and clean, grease it well to keep it that way.

If your electrical loads are stock or near stock an OE type alternator will get the job done. They discharged at idle when new and still do... and lived.

If you have a lot of added load like big stereo, big fuel pump or electric fan, A higher output alternator may be needed.

STEP 1, At idle, Check the alternator output at the battery terminal. IE: voltage
Step 2. At idle, Check the voltage at the battery terminals.
Step 3 increase RPM to 2,000 or so and repeat above tests.

Report back

Thanks to all for the help/ ideas..

All new wiring harness's ( year one M&H) silicone greased terminals at the bulkhead. Will remove and check.

As said above, stock amp gauge, but Redline changed to a volt meter, so NO wires going to it at all..

Newer electric VR being used.

I am going to run a wire from the alternator to the starter/battery stud.

So if I go to a squareback alternator, what will I have to do to my wiring harness to hook this up using the stock VR? What if I upgrade to the newer version of the VR?

My car is all stock, no big stereos, no power windows, no AC, so very little draw except for lights..

Another question here.... If my gauge is a volt meter now, why does the voltage go down so low at idle with the lights on?? I understand amp output is zip, but doesn't the voltage stay the same?

Again thanks to all helping me work through this...

lets say amperage are how many men pushing a car.

voltage is the force they have to put out to push the car

more men, less force each one

less men, more force they have to put each.

thats what voltage and amperage are.

so if there is not enough men to push the car ( amperes ), will need more force each to push it... thats when voltage falls down.

they are proportional.

V=I*R
so as amps go down, voltage goes down.
that is why it is a good indicator of charging.

as for mods. As I said, no mods needed, just ground the 2nd field on the alt.

there is a drawing of moding your wiring to use the new vr, but I prefer the grounding, since electronic is electronic. plus it gives me the choice of going back to a single field if I am on a trip and something happens and the parts store isn't stocking the dual field.

With a stock electrical system and new wiring you should not have a problem. However, mass rebuilt alternators are usually poorly done. A good local shop ought to be able to fix that for you. Everything else is just a bandaid.

in a previous car I had one of the 100 amp square backs put in.
a long time ago, I didn't know what to do electrical wise and had a shop put it in along with the 70's style voltage reg.

it worked fine for quite some time, but the connector they put on went intermittent.
it went to 100 volts and melted a 2 inch section of 10 gauge wire in the car. smoked another 2 inches from each side of the break.

I also upgraded a sb poly 318 to the square back from the parts store.
but kept the single field vr, since it was the solid state one anyway.
as said above, I used the 10 dollar gm chrome alt bracket and spacers to pull it out enough to bolt on.
worked fine till I replaced the engine.
it still dimmed a bit at idle at night.

even now with a 120 amp alt, I get pulsing at idle.
the voltage fluctates a lot at idle. running at 2k or so it is rock steady.

I was allmost to pull the trigger for the TuffStuff alt, but emailed them asking for iddle specs and told me their alt put at iddle around 45 amps. That retracted me on pull the trigger.

I don't need 100 amps alt max output, I need/wish 55 amps at iddle.

The power consumption on a car doesn't change a lot running on highway 100 MPH or sat on a traffic light ( just ignition variations ), so why I would care to get 100 amps at high revs ?

of course is logic, at high revs the stator inside the alt gets more fields variation ( hence more amps ) coming from rotor spining faster, but a stock replacement 78 amps also gives around 45 amps at iddle and priced less than a half tuffstuff are priced