Ok here it gos, i have a 1994 regal and ive had the alternator and the battery tested at the local auto parts store, and they both tested good. But for some reason i keep loosing volts....when im driving the volt gauge is almost always below 13 volts and at night the lights dim...if anybody could help that would be so awsome!

same problem, still searching for solution
 

84 regal. New alt, new batt, new ground wire, new positive lead too. Symotoms the same as above

Lets see if we can uncover some info here.
When the store checked the alternator can you remember how they checked it?
Here's why I ask; If an alternator is putting out say 20 amps, the light will go out the alt will test good if checked with no load and you could have problems when using the vehicle with a load of more than 20 amps like at night with the headlites on.
If they loaded the system and the alternator put out around 80+ amps then you might say it's good.
Next, check the wire coming from the alternator to the starter where it then goes to the battery. Some have a fusible link in the line to protect the system in case of a direct short. Feel the fusible link for possible broken internal wire which would give intermittent/insufficient charge to the battery when full output is required.
Some alt hot leads go directly to the battery. That wire needs to be thoroughly checked for good contact.
Last but not least if the hot lead going into the car to the voltmeter has a bad connection that can cause a low reading, also the ground for the dash instruments needs to be checked . You have your work cut out for you , let us know what you find.

He aquired this car a few days ago and it is in great condition except it wont charge.


So, as usual when we buy a classic and a part has an issue, we replace the whole system. We replaced the battery, the alternator, both battery cables, the two prong key tail and the engine to fire wall ground wire. Still no charge, but with the car running the car supports the ignition, but not accessory power. At night headlights will work dimmly but will kill battery dead. A quick jump works fine.

NOTE: I noticed above that you mentioned a wire from the Alt to the Starter with a fuseable link. I dont see this. Focusing on the 2 prong pig tail from the alt. One wire goes to the dash battery light, the other was on the back of the Alt on the screw stud which is also attached to the positive side of the battery.

The negative side of the battery is attached to the block and the left fender
The positive is attached to the starter and the Alt post.t

So... with a freshly charged battery


CAR OFF

Battery = 11 volts

Alt post to batt negative = 11 volts


KEY ON CAR OFF

Battery light = on

Dash volt meter = 13 volts

Battery = 11 volts

Alt post to Batt neg = 13


CAR RUNNING.

Batt = 11 volts

Dash volt meter = 13 volts

Alt post to Batt neg = 13 volts


CAR ON BLACK BATTERY OFF

Battery = 11 volts

Alt post to Batt negative = 13

Dash volt meter = 16


So folks, what is going on?

Thanks

I'm puzzled by the battery reading of 11 volts.
If you have a freshly charged battery and you are reading only 11 volts directly at the battery terminals , junk the junk battery. One other test , with the battery cables removed form the battery, what does the voltmeter read? If it reads less than 12.4 the battery is no good or is in need of charging.

The charging system on an 84 Regal is fairly simple.
This is what I would check.
1. Battery no load volts as it sits, should be around 12.4 volts
2. Cables for possible corrosion where connected to the battery and internally
3. Engine off, voltmeter connected to battery negative post and pos lead to alt hot post of alt should read battery voltage approx 12,4
4. With vehicle running at fast idle, voltage at alt terminal should read 14.2 -15 volts
5. If you have that voltage at alt then at battery + term should also read 14+ volts.
6. Turn on hi beam headlights, blower motor on high and voltage should remain at 14 volts when checked at the battery.
Somewhere you are not going to get these results, Let me know just where, in the preceding steps, and I should be able to tell you where your problem lies.

I am still having this same problem with my 1995 Park Avenue. I have put in two alternators and new wiring. My gage goes down and back up again. The red light blinks sometimes. Not always when the gage needle is boucing up and down. Sometimes the red light on gage just blinks or just the needle bounces. My headlights dim while driving. Then there is a burning wire smell. Just can't get figured out. Otherwise this has been a great car. My wife drives it to work every day.

buickbob,
Just from what I think you are trying to tell us here, I suspect you have a short somewhere in the electrical system. You might be getting the alt lite and dipping voltage reading because of the electrical short. The headlites are dimming because the short is robbing the rest of the system of voltage. And your voltmeter is showing just that.
Do you hear any kind of clicking sound like a circuit breaker opening and closing?
Where is the burning smell coming from inside the car or outside under the hood?
I will help you find the problem . Does the voltmeter do the up and down reading when the lites are off?
I need all the info you can provide like when it happens, what is on, and anything you can do to make it happen. I don't believe the alternators were your trouble at all.
Depending on where it is and how often it happens is important to know.
What wiring did you replace and why?
If you want to it will take some isolating to find the short , but we will!!

Hanky,

I appreciate the help. I am suspecting some kind of short also. I had the car at the mechanic shop and he check everything including putting a new altenator, Oreilly's furnished the alternator under warrenty. The mechanic also took the dash apart and the gage cluster but didn't fine anything wrong there. He said there is a control box in the dash that could be doing it but that was beyond his scope for testing. I ask him to keep looking for a short or something and he did find when he wiggled the single wire that plugs into the alt. going to the fire wall, then to the gage, the gage would drop below 13 volts and the lights would dim. I went to Buick dealer a purchase a new plug but it had 3 wires comming out of it. The parts guy said they probably just make the plug one way any more and just to tape off the other two wires which I did. I sodered the single wire with the battery disconnected and the plug out of the alt. to not damage anything else. Connected everything back up and drove it. Thought I had fixed it but after probably 10-15 minutes the gage dropped below thirteen volts again. The red light on volt gage still flickers at times also. The dips of the gage needdle and the red light are usually seperate, but sometimes together. So I checked the wiggled the wire again off the alt. and it would make the gage drop and lights dim so I resodered the wire to where the wire went into the wire harness as close as I could and drove it again. About 20 minutes, the voltage drops again. We still have the burnt smell that we can smell in or out of the car. It happens whenever. Sometimes after you start it and let it warm up or when you stop and park it. So that is where I am at now. We still drive the car and it is intermittent when it does it, with or without the lights on. I think maybe the wire could be bad between the soder joint and the firewall which is about 1.5 ft in length in a bundle of probably 50 wires. I think my next step is to replace this wire up to the firewall. I will have to take the wire bundle cover off and trace the wire to the firewall. Also, we do not hear any clicking sounds or any sounds like a breaker would make when this happens. I am sorry this is so long but wanted to describe what was going on. Thanks!

Our solution
 

In our case the solution was oddly simple. Replace the belt that drives the alternator. Good god we spent a fortune replacing every electrical part. Turns out it was the belt. Try to find one of those green hi friction belts.