Alternator is discharging

[Snotty]

The weather yesterday was beautiful here in Chico; 79* - a new record for this date! So, I took my Newport on a drive to Orland, some 30 miles away, when a Buddy asked for a ride to get his car from a shop.

No big deal, had a good drive, and a guy at the shop liked my car and we talked a bit. OK, I had a meeting at the church at 5:30, so I went straight there when Ron got his car back.

It was almost 7 when the meeting was over so I turned my lights on for the ride back home. They looked "dull" to me, but I dismissed it since I've been driving the Durango so much, and its lights are wonderful. So, when I hit the left turn signal and it hardly flashed, I thought something was wrong. Pulling into CVS Pharmacy the same thing happened, signal light barely blinked. I then looked at my Amp gauge and saw that it was indicating a heavy discharge.

I came to a stop and turned off my lights; amp gauge moved to the right a little, and went to to the center when I revved the motor. The rest of the ride home the lights stayed dull and the signals were very slow.

Thoughts?

 

[300rag]

First that comes to mind is the regulator, followed by alternator.

 

[Snotty]

First that comes to mind is the regulator, followed by alternator.

Voltage regulator, on the firewall? It did go out on me over ten years ago. Alternator is newer than that.

 

[300rag]

Voltage regulator, on the firewall? It did go out on me over ten years ago. Alternator is newer than that.

Yes, that's the one. I recently had that same problem with my wagon. New VR fixed it.

 

[stubs300]

You don't need to brag about your weather, there's lots of other places beside CA. with nice weather this time of year! You don't say what your working on, but read this. You'll learn a lot. Good Luck
charging system overview

 

[Not Right]

You don't need to brag about your weather, there's lots of other places beside CA. with nice weather this time of year! You don't say what your working on, but read this. You'll learn a lot. Good Luck
charging system overview

Thank you for this information. Printed it and put it in the file cabinet! I was always curious about this topic, and now I know.

 

[Zymurgy]

Sound just like what happened to me this fall, I agree with checking the voltage regulator. Make sure you get the one with electronic internals, I bought the cheaper one because it looked more like the stock regulator but it only lasted 2 months

 

[RJRENTON]

The weather yesterday was beautiful here in Chico; 79* - a new record for this date! So, I took my Newport on a drive to Orland, some 30 miles away, when a Buddy asked for a ride to get his car from a shop.

No big deal, had a good drive, and a guy at the shop liked my car and we talked a bit. OK, I had a meeting at the church at 5:30, so I went straight there when Ron got his car back.

It was almost 7 when the meeting was over so I turned my lights on for the ride back home. They looked "dull" to me, but I dismissed it since I've been driving the Durango so much, and its lights are wonderful. So, when I hit the left turn signal and it hardly flashed, I thought something was wrong. Pulling into CVS Pharmacy the same thing happened, signal light barely blinked. I then looked at my Amp gauge and saw that it was indicating a heavy discharge.

I came to a stop and turned off my lights; amp gauge moved to the right a little, and went to to the center when I revved the motor. The rest of the ride home the lights stayed dull and the signals were very slow.

Thoughts?

Sir,
My thoughts in order of checking ....
1. What year is the car
2. If its pre 1970 it uses a mechanical regulator with only one field connection to the rotor. The sevond brush is grounded at the alternator. The mechanical regulator is prone to failure resulting in no rotor current and no alternator output.
3. The write up by another perdon is excellent explanation on how the electronic regulator works. The regulator switches the rotor current on-off to maintain approx. 14.0 charging voltage (+/-). Its very likely that you have an open diode ...... which results in low output AND and low voltage under high load.
4. If you have a "square back" alternator, they use a different diode arrangement .....positive diodes spot welded to a heat sink, totally isolated from ground . The negative diodes are also spot welded to a grounded heat sink anf form the other half of the three phase full wave bridge rectifier arrangement.
In my opinion, my preference is the round back design but because the diodes are pressed into their heat sinks, they require special tools to remove/install new diodes.
Alternators are simple devices and are easy to test snd fix.
Everything is explained in FSM....and every year is subtly different...PM me if you need additional information.
Bob Renton

 

[Snotty]

Sir,
My thoughts in order of checking ....
1. What year is the car
2. If its pre 1970 it uses a mechanical regulator with only one field connection to the rotor. The sevond brush is grounded at the alternator. The mechanical regulator is prone to failure resulting in no rotor current and no alternator output.
3. The write up by another perdon is excellent explanation on how the electronic regulator works. The regulator switches the rotor current on-off to maintain approx. 14.0 charging voltage (+/-). Its very likely that you have an open diode ...... which results in low output AND and low voltage under high load.
4. If you have a "square back" alternator, they use a different diode arrangement .....positive diodes spot welded to a heat sink, totally isolated from ground . The negative diodes are also spot welded to a grounded heat sink anf form the other half of the three phase full wave bridge rectifier arrangement.
In my opinion, my preference is the round back design but because the diodes are pressed into their heat sinks, they require special tools to remove/install new diodes.
Alternators are simple devices and are easy to test snd fix.
Everything is explained in FSM....and every year is subtly different...PM me if you need additional information.
Bob Renton

Thanks Bob. My car is a '70 and I've swapped all for Mopar Performance electronic ignition. The regulator and alternator gave out in the last ten years and I replaced both. This sudden event surprised me.

 

[Snotty]

Put a new voltage regulator on the car this morning - fixed!! Soon as I started it the ammeter went towards charging. I started it up before doing the swap and it was still discharging.

Thanks friends!