Charging, but not enough

[MattRR]

Hello everyone, new to the Mopar world and looking for some help on a ‘68 Roadrunner 383 that’s not charging. Sniper EFI screen shows 12.2 volts, dash gauge is dead center on the line between charge and discharge.

- New alternator (correct for year / single field), tested by O’Reillys to Be fully functional
- New regulator (I also tried the old regulator which provides the same 12.2v)
- Alternator has a good ground (0.4 ohms to battery negative terminal; verified at both the negative terminal on the alternator and to the alternator housing)
- Wire between alternator and regulator is good. 0.2 ohm.
- Disconnected the field wire from the alternator and there was no change to the voltage.

I’m certainly not an electrical expert and I’m (don’t judge) far more familiar with LS stuff. I was surprised at the thin gauge of wire coming off the alternator and that it didn’t go straight from the alternator to the battery.

Any suggestions you all have, I’d greatly appreciate it!

 

[Don67Satellite]

Hmm, you seem to have the bases covered. I'm leaning toward the new regulator being a dud?

 

[MoparLeo]

That is a common mod done to them. Very important! Make sure to fully charge the battery, disconnected from the car with a battery charger. Use low amp setting for at least 8 hours. Fully charged battery must be 12.6 volts minimum. At rest. Original spec alternators only put out 60 amps with a heavy duty alternator.

 

[1 Wild R/T]

First test, engine running, use a jumper to apply 12v to the small (field) wire going to the regulator... Be ready to read the voltage pretty quick cause if the alternator is good & if you leave that wire connected the voltage will climb rather quickly.

If the voltage climbs the alternator & wire from the regulator to the alternator are good..

If the voltage doesn't climb move the jumper to the field terminal of the alternator... Same thing, if the voltage climbs the alternator is good.. Inspect the wire from he regulator to the alternator..

If not the alternator is suspect...

Plenty more testing can be done but thats a good start..

 

[eldubb440]

- New alternator (correct for year / single field), tested by O’Reillys to Be fully functional

I'll place my bet here

 

[Nacho-RT74]

12.2 volts and zero reading on ammeter is very souspicius. It should be zero reading on ammeter and voltage closer to 13 or 13.5. 12.2 volts could/should show a needle slightly to the discharge side, or a needle flickering at least, going to charge side when revving up on more less same proportion depending on how much time was flickering to the discharge side.

Average ZERO READING IS THE BEST/CORRECT status on the charging system at the slowest engine speed ( at iddle if possible ) to confirm you have the right alt for the car requirements.

This is just if all the accesories are correctly connected to the alt side and not to the batt, just like the factory design is/was intended. And of course, the charging network is still in stock configuration

The regulator field wire to the alt it comes from ignition system side. There is no a "sensing" wire like the GM setup where alt is internally regulated, so you won't find any small wire between batt and alt. Regulators in Mopars works and sense everything with the same wire coming from Ign network, then send their signal to the alt, either on single and dual filed systems.

 

[Nacho-RT74]

And just taking a step forward before any disagree wich is being floating latelly ( just to bother ) here is a statement from Chrysler literature to support my post.

 

[Nacho-RT74]

Question... do you have discharge on ammeter when opening doors before crank the engine?... turn on lights to show a better reading, but with just the dome light on after open and keep the door it should show a small discharge reading.

Also after crank the engine, ammeter should show charge to show the load going back to the batt, recovering what the batt lost to feed the starter motor

 

[MattRR]

Hmm, you seem to have the bases covered. I'm leaning toward the new regulator being a dud?

Don, I did try both regulators (new and old). No difference in voltage output. I could try a third if you think that‘d be helpful. Are there any component tests I can do on the regulator to verify whether or not it’s functional?

That is a common mod done to them. Very important! Make sure to fully charge the battery, disconnected from the car with a battery charger. Use low amp setting for at least 8 hours. Fully charged battery must be 12.6 volts minimum. At rest. Original spec alternators only put out 60 amps with a heavy duty alternator.

Leo, I will give that a try. Two additional points I should have noted in the initial post. The battery is a brand new Optima. It’s been on a trickle charger since the day I bought it. It’s also the second battery (12.2v was noted on the first battery as well).

Out of curiosity, what accessories would require the high amperage alternator? The car is stock, with the exception of the Sniper EFI I just installed. No stereo, fancy headlights, no A/C, etc. I would think electrical loads would be minimal. For what it’s worth, the low charging condition existed last fall as well (back before the EFI) which is why I started with a new battery this year.

First test, engine running, use a jumper to apply 12v to the small (field) wire going to the regulator... Be ready to read the voltage pretty quick cause if the alternator is good & if you leave that wire connected the voltage will climb rather quickly.

If the voltage climbs the alternator & wire from the regulator to the alternator are good..

If the voltage doesn't climb move the jumper to the field terminal of the alternator... Same thing, if the voltage climbs the alternator is good.. Inspect the wire from he regulator to the alternator..

If not the alternator is suspect...

Plenty more testing can be done but thats a good start..

Thank you R/T, I will definitely give this a shot when I head out to the shop!

I'll place my bet here

This is the second alternator if that impacts your thoughts. The previous alternator charged at 12.2v also, but the power stud was loose, so I replaced to just to be sure that wasn’t the issue.

12.2 volts and zero reading on ammeter is very souspicius. It should be zero reading on ammeter and voltage closer to 13 or 13.5. 12.2 volts could/should show a needle slightly to the discharge side, or a needle flickering at least, going to charge side when revving up on more less same proportion depending on how much time was flickering to the discharge side.

Average ZERO READING IS THE BEST/CORRECT status on the charging system at the slowest engine speed ( at iddle if possible ) to confirm you have the right alt for the car requirements.

This is just if all the accesories are correctly connected to the alt side and not to the batt, just like the factory design is/was intended. And of course, the charging network is still in stock configuration

The regulator field wire to the alt it comes from ignition system side. There is no a "sensing" wire like the GM setup where alt is internally regulated, so you won't find any small wire between batt and alt. Regulators in Mopars works and sense everything with the same wire coming from Ign network, then send their signal to the alt, either on single and dual filed systems.

Sorry, I wasn’t very clear on this. The ammeter looks to be discharging all the time. The needle sits 1/32” - 1/16” left (discharge) of the center line on the gauge. It does bounce occasionally, but always toward discharge. I guess I’ve been more focused on the voltage (read on the Sniper screen) than ampere (read on the 50 year gauge).

 

[MattRR]

A few extra / new notes.

Most important) I ran a wire straight from the battery to the alternator field terminal. Changing the engine RPM resulted in an increase in voltage. Around 3,500 rpm the voltage was around 15.5 volt and I let off. This tells me the alternator is good.

1) I verified the regulator has voltage coming in, so that connection is correct. It’s straight off the ballast resistor.

2) there’s zero volts at the alternator field wire, even when I adjust the RPM of the engine.

3) the pins in the voltage regulator plug (2 pins) looked bad, so I replaced the connector to be safe. Both the input (center pin) and field output (toward driver’s side) are now firmly on the regulator pins. I slide the rubber shield back and verified voltage on the input pin and verified continuity between the output pin and the alternator field.

4) I bypassed the regulator all together (taped input and output pins together) and voltage climbed with engine RPM just like in “most important” above. This confirms input regulator voltage is good.

5) because I’m at my wits end and was afraid I was reading the schematic wrong, I swapped pins on the regulator. This made the center pin (should be input) go to the alternator field and the drivers pin (should be output) get 12V. Voltage climbed with engine RPM just like “most important” and #4 above.

6) just to be certain, I duplicated all of the above steps with the old regulator and got the exact same results.


Any and all input is appreciated. I am really out of thoughts at this point.

 

[1 Wild R/T]

Sounds like your describing a 70 & up style regulator & harness which won't work with a 69 & earlier style alternator....

70 & up style regulator

69 & earlier style regulator

If you can verify which regulator you have we can tell you how to proceed..

 

[MattRR]

Yes sir, I definitely have the 1970 and up style based on the pictures you provided.

I suppose the next step is to buy a pre-70 regulator?

 

[1 Wild R/T]

Yes, The 70 & up regulator grounds the field wire since power is fed into the field on the second wire... 69 & earlier the second terminal doesn't exist, that connection is internally grounded... So basically right now your grounding both ends of the field winding... Sounds like you should be up & running in no time...

 

[MattRR]

Thank you so much! I’ll report back when I have a new regulator in hand.

This car was restored over 20 years ago. I can’t imagine how the previous owner dealt with the lack of charging all that time.

 

[1 Wild R/T]

Thank you so much! I’ll report back when I have a new regulator in hand.

This car was restored over 20 years ago. I can’t imagine how the previous owner dealt with the lack of charging all that time.

Wow... Must have spent more time sitting in his shop looking pretty than actually out driving... I've never understood it & I have a few friends that do exactly that...

 

[1 Wild R/T]

Quick question, any chance theres an un-used blue wire behind the alternator? Perhaps it was converted to a 70 & up style alternator? If that were the case there would be 12v (more or less) being fed to the alternator by the blue wire & the green wire going back to the 70 & up style regulator would ground the field....
FWIW the 70 & up style system does have a reputation for being more reliable..

 

[451Mopar]

1 Wild R/T info should get you on track. The only thing I can add is make sure the voltage regulator case is well grounded to the firewall, and the firewall grounded to the engine block. If the regulator does not have a good ground, the regulator will not work. You can test with a jumper wire from a bare spot on the regulator case to a known good ground point.

 

[MattRR]

Update time. Picked up a brand new regulator for a 1968, it looks exactly like the “1969 & earlier style” 1 Wild R/T posted. Removed the previous regulator, installed the new one. Wiring is as follows:
- 12V ignition into passenger side of the ballast resister
- driver’s side of ballast resister wire goes to input (“IGN”) on the regulator
- output (“FLD”) wire on regulator goes straight to alternator field input

Good news: ammeter shows it’s charging. Had the car running, turned on the headlights, fan, and radio and ammeter continued to show the system was charging.

Bad news: Sniper screen shows 12.4-12.7V. Better than it was, definitely still not what I expect.

Other notes:
- I’m confident it’s a 1969 & earlier alternator. There’s only one field terminal on it.
- I was lazy and mounted the new regulator directly to the old regulator bracket. The result is the regulator is likely 90 degrees from what it ultimately should be, meaning the terminals are at the 12 o’clock and 6 o’clock position. Ideally I’d rotate it in winter while the car is in storage. I can’t imagine the regulator is position sensitive, but please let me know if I’m wrong.

Sorry to be such a newb with so many questions. I rarely appreciate all the help and suggestions so far.

 

[1 Wild R/T]

The regulator doesn't care about the angle... Is that voltage at idle? Does bringing the rpms up cause the voltage to rise? Have you tried reading voltage directly at the battery & directly at the battery stud on the alternator with a digital handheld meter? When are you picking up voltage for the Sniper?

As far as Newbie, your brave enough to try an EFI install & your getting a lesson in electrical... We all gotta learn it somewhere & at sometime... We weren't born with it... Someone taught each of us...

 

[451Mopar]

I would upgrade the charging system if running EFI. The early alternators did not have much current output, and even less output at idle speeds. The original style regulators were also mechanical so the output will not be as steady as the electronic regulator.
The Powermaster 95A 7519 (single groove pulley, 71 and up Square back alternator) would be my choice.
Powermaster 7519 Powermaster Retro Alternators | Summit Racing
Dual groove pulley for A/C cars is #7509.
They also sell these with an internal regulator, but I like the external adjustable regulator.

The 7018 early style round back version would also work and look more original.
Powermaster 7018 Powermaster Retro Alternators | Summit Racing
Dual groove pulley for A/C cars is #7019.

Link to Powermaster catalog (pages 102-103): POWERMASTER PERFORMANCE

Both these alternators can use either early style or later style regulator. Use the stock size crank pulley, not the aftermarket underdrive pulleys.

My choice for regulator would also be the 71 and up style TransPo C8313 Heavy duty adjustable voltage regulator.
C8313 on Amazon $34.99 with connector pig tail. Sorry Amazon links don't seem to work?
Also on Ebay for $41.95: Transpo Heavy Duty Adjustable Voltage Regulator C8313 - for sale online | eBay

If trying to maintain the stock look, there are electronic versions of the earlier style regulator also:
Chrysler Plymouth Voltage Regulator Electronic Solid State Dodge Mopar Body A B | eBay

Then add a large gauge (at least 8 AWG) wire from the alternator output directly to the battery to by-pass (mostly, but in parallel) the stock ammeter and bulkhead connections.
You can retain the original alternator output wire connected to the alternator, to keep the ammeter from showing discharge, but it will need to be fused.