Alternator overcharging

[gran coupe john]

Didn't want to put my opinion in. I used to rebuild these alternators. When the voltage fluctuates like that it is either the rotor or the stater is bad. Just worth checking.

 

[CASCA2525]

great day when

72RoadRunnerGTX​

DROPS
a video

I really wish you had been my auto elec instructor in my trade lvl one course

 

[Challenger RTA]

I didn't mention it and I don't see it mentioned.

A bad diode in the Alternator can also cause overcharging , 14.2 - 14.6 is normal voltage. Maybe it was in the video.

Get it checked.

Will go into other details if you find it's good.

 

[Former owner]

Just a thought....if memory serves correctly, a 70 model would be using the single field alternator. My 71 had the single type. When the dual field type came along later, it could be used on the older models, but one of the field connectors was either grounded, or not connected at all; I don't recall which. It's been a while... I can't tell from your photos which is the case on yours, but I'd bet that is the path to follow. To echo a previous remark, it sounds like your alternator is "full fielding". It may have to do with the secondary field wire being grounded. I seem to remember that's how we did it to test output.

 

[72RoadRunnerGTX]

Just a thought....if memory serves correctly, a 70 model would be using the single field alternator. My 71 had the single type. When the dual field type came along later, it could be used on the older models, but one of the field connectors was either grounded, or not connected at all; I don't recall which. It's been a while... I can't tell from your photos which is the case on yours, but I'd bet that is the path to follow. To echo a previous remark, it sounds like your alternator is "full fielding". It may have to do with the secondary field wire being grounded. I seem to remember that's how we did it to test output.

1970 was the first year for the dual isolated field alternator and the related electronic voltage regulator across all Chrysler product platforms. When using a later dual isolated field alternator on a ’69 and earlier mechanical regulator application, one bush terminal needs to be grounded.

 

[Former owner]

1970 was the first year for the dual isolated field alternator and the related electronic voltage regulator across all Chrysler product platforms. When using a later dual isolated field alternator on a ’69 and earlier mechanical regulator application, one bush terminal needs to be grounded.

Odd....I had a 71 Cuda, and a 70 Dart. Both had the single field alternator, along with the electronic voltage regulator.

 

[72RoadRunnerGTX]

Odd....I had a 71 Cuda, and a 70 Dart. Both had the single field alternator, along with the electronic voltage regulator.

Not possible I’m afraid, the factory electronic regulator requires a dual isolated field alternator (two field terminals both insulated from the case) whereas it controls the field current on the low or negative side of the field, ignition 1 keyed power on the other field terminal, both of them can not be grounded. The older mechanical regulator controls the field current on the high, or positive, side of the field with the other brush being grounded to the case, having only one field terminal.

 

[Apewalski440]

Sorry for the delay .

Here is the news :

Tried to not bypass the Ammeter (so I connected the black wire on the BAT post of the alternator, with the charge wire), better, at cold idle, 1200, I'm around 14.5. Drove few minutes, had smalls peaks aboves 15, but never above 16.

Out of curiosity, and because I still found that high, I tried with the old alternator (No charge wire, like it was when I bought the car). A small 12... So I think I changed it because it was clearly dead.

So I put back the Powermaster alt, I connected again the black Ammeter wire on the BAT post of the alternator (still with the charge wire), but this time I didn't connected the black and red wire behing the Ammeter gauge, but just tied them together. This time it didn't charge, I was around 12.

If I put a 125 mega fuse on the charge wire, do you thing can I let the Ammeter connected without risking a fire ?

If I have to bypass the Ammeter for security, what did I miss with my bypass ? Did I need another ground somewhere ? (Because with my bypass, none of the red and black wire touch the cluster, while the cluster is grounded, these are my beginer's conclusions...)

Thanks.

 

[pschlosser]

Tried to not bypass the Ammeter (so I connected the black wire on the BAT post of the alternator, with the charge wire), better, at cold idle, 1200, I'm around 14.5. Drove few minutes, had smalls peaks aboves 15, but never above 16.

This is too much work for me to understand. I really want to help you not fry your wiring and/or other elements of your car. If you could show me a wiring diagram of what you connected, it will be easier for me to understand.

I think you are saying you left the charging wire (shown in RED in the image below) from the alternator BATT still connected to the battery POS, but also connected the ammeter to the BAT, is that correct?

 

[Apewalski440]

This is too much work for me to understand. I really want to help you not fry your wiring and/or other elements of your car. If you could show me a wiring diagram of what you connected, it will be easier for me to understand.

I think you are saying you left the charging wire (shown in RED in the image below) from the alternator BATT still connected to the battery POS, but also connected the ammeter to the BAT, is that correct?

View attachment 145699

Sorry it may be difficult to understand me because I am French.

Yes, This is what I did for the first test.

After that, I just disconnected the black and red wire behind the Ammeter, and tied them together (to avoid burning the ammeter), but it didn't charge like that.

 

[pschlosser]

After that, I just disconnected the black and red wire behind the Ammeter, and tied them together (to avoid burning the ammeter), but it didn't charge like that.

Then I think you still have a voltage regulation problem.

Bypassing the ammeter is fine, I don't think there are any dangers there. But please tell us you still have the blue (~60A) fusible link in place protecting the power between the battery POS post and the RED wire going through bulkhead connector #16. Since you have connected the BATT from the alternator directly to the battery POS post, the only thing using the current on the black wire at the ammeter (which usually feeds back to bulkhead connector #18) is mostly the fuse-protected systems in the car.

Your 125A fuse does little to protect anything, and may be removed. The alternator will never put out more than 90A (more or less). so that fuse will never pop.

Make sure your voltage regulator is WELL GROUNDED. You may need to scrub off some paint on the screw flanges on the voltage regulator to make good contact with the cowl. I see in one photo you are running another ground wire from then engine to the cowl. That is good.

Make sure the engine is well grounded to the body frame. There is usually a braided strap that runs from the transmission-engine bolt (often near the starter motor) to the frame rail.

Make sure the Alternator is well grounded to the engine.

By well grounded, I refer to using a wire brush to scrub away any rust, corrosion, dirt and grease to make sure these areas connect very well. They must be able to handle the 90A output by the alternator.

 

[pschlosser]

Sorry it may be difficult to understand me because I am French.

Please do not be offended. I am feeling impatient, today. Too much cafe. Anyone describing a wiring condition has to be able to see it and visualize it in their minds. Even my descriptions in the posts above require one to "see them" and a diagram makes that easier.

 

[72RoadRunnerGTX]

Careful with that battery to alternator “shunt wire” bypass, it creates a parallel current path for the stock charge path, defeating/circumventing the stock circuit protection (fusible link) for all the unfused wiring in the car. Severe risk of fire should a short occur anywhere in the stock unfused wiring or components.

 

[Apewalski440]

Please do not be offended. I am feeling impatient, today. Too much cafe. Anyone describing a wiring condition has to be able to see it and visualize it in their minds. Even my descriptions in the posts above require one to "see them" and a diagram makes that easier.

Don't worry I'm really not offended

 

[Apewalski440]

Careful with that battery to alternator “shunt wire” bypass, it creates a parallel current path for the stock charge path, defeating/circumventing the stock circuit protection (fusible link) for all the unfused wiring in the car. Severe risk of fire should a short occur anywhere in the stock unfused wiring or components.

Thanks !

 

[Apewalski440]

Then I think you still have a voltage regulation problem.

Bypassing the ammeter is fine, I don't think there are any dangers there. But please tell us you still have the blue (~60A) fusible link in place protecting the power between the battery POS post and the RED wire going through bulkhead connector #16. Since you have connected the BATT from the alternator directly to the battery POS post, the only thing using the current on the black wire at the ammeter (which usually feeds back to bulkhead connector #18) is mostly the fuse-protected systems in the car.

Your 125A fuse does little to protect anything, and may be removed. The alternator will never put out more than 90A (more or less). so that fuse will never pop.

Make sure your voltage regulator is WELL GROUNDED. You may need to scrub off some paint on the screw flanges on the voltage regulator to make good contact with the cowl. I see in one photo you are running another ground wire from then engine to the cowl. That is good.

Make sure the engine is well grounded to the body frame. There is usually a braided strap that runs from the transmission-engine bolt (often near the starter motor) to the frame rail.

Make sure the Alternator is well grounded to the engine.

By well grounded, I refer to using a wire brush to scrub away any rust, corrosion, dirt and grease to make sure these areas connect very well. They must be able to handle the 90A output by the alternator.

Thanks, I checked carefully the voltage regulator and alternator ground, but not the body frame, I will check that. Thanks.

Edit : of course I still have the blue fuse, the only thing I did is put the charge wire, and try this with ou without the Ammeter.

 

[Challenger RTA]

The below explains the Stock Alternator and battery circuit.

 

[pschlosser]

Thanks, I checked carefully the voltage regulator and alternator ground, but not the body frame, I will check that. Thanks.

Edit : of course I still have the blue fuse, the only thing I did is put the charge wire, and try this with ou without the Ammeter.

Let us know how it goes. Have a fire extinguisher close by.

 

[Challenger RTA]

When doing an alternat Alternator feed to the amp meter.

It would be advisable to abandon the feed from the alternator R6 12BK, ( Bulkhead connector 18 ) and use an alternative way of feeding it. That being the feed to Splice 1 from where all loads are feed from the alternator feed.

An alternative feed can connect to the back of the Amp gauge. R6A stud. The original wire in the dash harness can be left in place providing 2 things. 1 The wire is in good condition and didn't melt any other wires in the harness. ( disconnect from amp meter and heat shrink) 2 The original feed from the alternator needs to be disconnected at the alternator or bulkhead connector.

In theory this would be electrically the same as stock, feeding the loads from the alternator to spice one. Just not going through the bulkhead connector.
The alternator feed was never fused. As said before the diodes would blow. But why take a chance. Place a fuse on the back of alternator or elsewhere.

 

[Challenger RTA]

As for the A1 12R circuit, Bulkhead connecter 16. Feed for maintaining state of charge of the battery and feeds loads when motor not running.
It can be bypassed in the same manner. connecting A1 12R side of the amp gauge to Keeping the provisions in mind from above. Bypassing the bulkhead connector.
(disconnect A1 12R from amp meter and heat shrink)