1966 newport 383 over charging?

[Newport 664door]

Wondering what charge rate should be, not sure of alternator rating. I'm getting 12.3 at the battery before starting, then 15.5 at high idle, turn on headlights etc, drops to between 14.1 & 15 .2 , even at low Idle, stays at 15 .3 when car is running fast or slow. Still has original voltage regulator, looking at replacement for it, but how do I tell if I have a single or double field alternator? Alternator looks original too. Any help thanks

 

[rags]

voltage regulator is probably stuck and is full fielding the alternator. here's a nice picture that i found showing the difference between single and dual field. single on the left which is what yours should be.

 

[Newport 664door]

Thanks, that helps alot, I'll take a look underr the hood and see what I have. I know a member on this site sells replacements on ebay. I still have the old style regulator, according to my Chilton manual has adjustments that need to be made that look complicated.

 

[Big_John]

Wondering what charge rate should be, not sure of alternator rating. I'm getting 12.3 at the battery before starting, then 15.5 at high idle, turn on headlights etc, drops to between 14.1 & 15 .2 , even at low Idle, stays at 15 .3 when car is running fast or slow. Still has original voltage regulator, looking at replacement for it, but how do I tell if I have a single or double field alternator? Alternator looks original too. Any help thanks

If your car has the stock, mechanical regulator, the later, "dual field" alternator won't work with that.

Look at the back of the alternator. If there's three wires, two to field connections and one to the output stud, it's a "dual field". Only two wires, one to the field and one to the output stud, it's a "single field".

If there's two wires and a wire that's grounding out the second field connection on the alternator, it's a "dual field" alternator with the second field connection grounded to make it work like a "single field".

Actually, the single and dual fields are misnomers. It should be "isolated field" for the alternator with two field connections. There aren't two fields in a "dual field".

 

[Big_John]

voltage regulator is probably stuck and is full fielding the alternator. here's a nice picture that i found showing the difference between single and dual field. single on the left which is what yours should be.View attachment 602347

Yes, the one on the right will always be a "dual field" or more correctly "isolated field" alternator. It's also known as the square back and desirable because it's easy to change the diode bridge.

I have to disagree on the one on the left as it can be had in both single and dual. In 1970 and 71, the dual field alternators had a "round back" case and 1972 up had the "square back".

That's OEM and not aftermarket... The aftermarket versions seem to be round back (FWIW).

 

[Newport 664door]

I can't think of a better way to spend Father's day, then getting under the hood and dirty. Thanks for all the tips, I'll get back to it later on

 

[Big_John]

Here's a real good thread on FABO on alternator ID.

Identifying Chrysler Alternators (1960-1976)

 

[Newport 664door]

Here's what I have, dual field?

 

[Big_John]

Yes, that is a "dual field" or isolated field alternator.

Note the red wire grounding out the second field connection. In a "single field" alternator, that end of the field is grounded internally.

 

[Newport 664door]

Found this while I was looking through original owners stack of receipts to see if alternator was changed

 

[Newport 664door]

Ok, then I can order a voltage regulator from FURYGT on ebay. Thanks!

 

[Big_John]

see if alternator was changed

It was changed, no doubt. That style alternator wasn't available until 1972.

 

[413]

Make sure the voltage regulator is grounded, if not it will overcharge.

 

[Newport 664door]

Appreciate all the tech, tips and pics, I'll dive back under hood tomorrow , clean up some grounds and wiring etc. Just did starter and starter relay last month, upgraded ignition to igniter 2 coil, wires and points eliminater few months ago, runs like a top, just seems like I gotta replace 1 old part at a time. Thanks again

 

[rags]

Yes, that is a "dual field" or isolated field alternator.

dual field alternator, but wouldn't that still be a single field system? regulator feeds positive to the field?

 

[FURYGT]

Ok, then I can order a voltage regulator from FURYGT on ebay. Thanks!

Thanks! FYI, I recommend measuring voltage at the battery. 12.3 before starting is low. After starting and after the battery is charged you should see voltage in the mid 13 range. Right after starting, you should see low to mid 14 volts as the battery is being charged. 15 & over indicates that there is an over charge situation. I hope this helps you.

 

[Newport 664door]

Thanks! FYI, I recommend measuring voltage at the battery. 12.3 before starting is low. After starting and after the battery is charged you should see voltage in the mid 13 range. Right after starting, you should see low to mid 14 volts as the battery is being charged. 15 & over indicates that there is an over charge situation. I hope this helps you.

Thanks, it slowly cranks at 12.1, once I get it to 12.3 it starts fast, then jumps to 15.5, battery is probably on way out too, that's next in line, just updating older parts and pieces as I go along. The starter was a nightmare , all anybody had was the shorty style, which put the wires way to close to block, if you could even get them on. Had the original starter rebuilt, and put a new starter relay in at same time. Soon enough all the old will become newer.

 

[Sixpactogo]

If this has been going on for a while, the 15 volts may have taken it's toll on the battery. Probably cooked the water out of it. You may just have a bad ground on the regulator causing all of your problems. As 413 mentioned in post 13 you need to verify a good case ground on the regulator.

 

[Big_John]

dual field alternator, but wouldn't that still be a single field system? regulator feeds positive to the field?

There's really no huge difference in the alternators. With the single field connection alternators, if you look where the brushes mount, you'll see that one brush has a terminal that connects to the regulator and the other brush goes directly to the case, thus grounding that end of the field.

With the dual, one brush terminal connects to the regulator and the other goes to power. Both brushes are isolated from the case. The regulator for this controls the negative side of the field rather than positive side like the pre 1970, single field does.

The 1970 and up regulator controls negative side as it is cheaper to build because you don't have to insulate the internal bits like you would if it was controlling the positive side.

When you use a dual field in a pre 1970 car, all you are doing is grounding the end of the field to use it with the earlier regulator.

There is a lot of confusion about the two, with people thinking that the "dual field" has two fields, when it really just has two field connections. I really prefer using the terms "isolated" and "non-isolated" fields.

 

[rags]

There's really no huge difference in the alternators.

thanks. thinking about it, there are two brushes in all alternators. just a little matter of how they are wired and regulated internally or externally. asking in context of buying parts for this vehicle. it has a dual field alternator but it's configured for a single field system. if the vehicle is still wired as a single field system then parts purchased for it would be specified as such. just want to be clear as to which type of system he should be ordering parts for.