Charging problem

[chargd72]

When my Charger is idling and accelerating the ammeter constantly reads slightly into the drain side.  If I hit the brakes or use the turn signals the pin drops even further into the drain side.  I thought I had a faulty alternator so I swapped the new one out for another new one.  I thought the chances of getting two bad ones was low.  I'm running a 78 amp alt and the only aftermarket electrical loads I have is a Mallory ignition box, aftermarket stereo and tach.  

Here is a video of the car at idle with turn signal on then applying brake.

https://www.youtube.com/watch?v=Ie7maKCzUD8&feature=youtu.be

[Nacho-RT74]

it is pretty much normal to get a flickering to discharge reading when turning or hazzards. The blink impulse is too fast to be recovered on time and before get the discharge reading.

I can't see a big problem there.

giving gas, the flickering should be smaller though, but usually allways present.

Note when you press brakes, the needle flick to discharge but a second later gets allmost recovered to center.

whats your iddle speed ?

[chargd72]

The needle went back to the middle when I released the brakes.  It will stay on drain as long as I hold it.  I would think it wasn't a big problem too except I had to get towed home last week because my battery died (new optima).  Charged it and car fired right back up. 

I'm beginning to think my cheapo Autozone regulator is the problem.  It comes with a rubber coating and a lot of people are complaining that they can't get a good ground on these.  I might have to find a steal casing one.  I'm hoping that will solve it.

Idle speed it pretty high with my 340 resto cam.  Close to 950.

[Cooter]

GM 1 wire. Problem solved.

[Pete in NH]

HI,

As Nacho said what you are seeing at idle is typical of these alternator systems. However, you should see the ammeter swing into the positive side as the engine RPM's increase. If that doesn't happen as you accelerate, I would but a voltmeter across the battery. As you run the engine up from idle you should see 13.8 to 14.4 volts on the meter. I suspect since you're on your second alternator the voltage regulator or something in the field wiring is open.Or as you mentioned the regulator Case is not grounded.  The blue field wire should have 12 to 14 volts on it and the green wire will be lower somewhere around 8 volts or so. Over the years I've not had good luck with aftermarket electronic regulators in these systems. The Mopar ones seem to last much longer. I think the current Mopar # is 4529794

[Nacho-RT74]

well, the flicking needle will be an usual reading no matter the alt. The power from alt AND how fast is the regulator to send the increase power signal is what will tell how large is the flicking needle. Sometimes can be allmost unnoticeable.

the charge back reading when giving gas could be normal on a stock old alt, but on a 78 amps later stock alt, could be allmost unnoticeable, since iddling should be enough to charge it back without a big load reading on ammeter.

another reason for a bigger or smaller flicking needle with a 78amps stock alt could be the quality of conections...bulkhead, amm studs, etc...

950 RPMS seems a little bit high for that alt to be able to keep sourcing. They usual are able to feed quite good at 800-850, giving around 40-45 amps.

I have being able to get a system able to recharge a death batt at iddle with just 2/3 of the amm full scale in maybe 20-30 minutes just iddling with stock alts and good and clean conections, and still be safe. For a while the times goes by, the needle goes to center slowly in that time

a good quality regulator could be a good reason to get a better charge, however, check all conections related, including reg clug and field terminals.

Locally I never have found a bad quality regulator really, however I went to the MP stock replacement one just for correct look. Works perfect!

[chargd72]

Thanks guys.  I'll give my connections a look over but will most like order that regulator from summit.

[chargd72]

Confirming it was indeed the voltage regulator.  Beware of buying those BWD el cheapo products from your local auto store.  Convenience and quality are a thing of the past.

[A383Wing]

if you can find one of these "thinner" winding alternators, they will charge better at idle..also, use the smallest pullet possible....I'm talking about the "middle" part of alt that is between the 2 case halves

but as mentioned, the "discharge at idle" is pretty much normal

[Nacho-RT74]

yeap, I have talked about those lates mopar alternators on my wiring and alt upgrade thread... but need to take care, some are still 60 amps which are better than the originals earliers, but some others the famous and latelly increased in interest, 78 amps alts which are a great improvement

they are about 1 or so milimeter wider and can fit a little bit tight into stock location in some years setups. Myself, had to use longer belts, because the back of alt meets the block in 3rd gens. Also trim a little bit the rear spacer to head bracket. This doesn't happen on some earlier years I think