69 dart one wire charging system

[nutz]

had the dart out today started fine
after the car show battery was dead
i have no idea when it stopped charging
lucky we bump started it and got home
and my home volt meter is dead
so all i had was my small battery charger
10.4 volt at battery
10.4 at alt
alt looks new (had the car for three years)
reg has what i think is two wires
so queston is to full field alt do i power (12v) or ground the field wire
then the other wire on reg i would think is key on voltage
dont think the reg ground is a problem but will test when i have a working volt meter
thanks

 

[DeadDodgeGarage]

On a '69, if the charging system is original, you would have the boxy looking voltage regulator and just one small wire going to the alternator brush connection. To temporarily full-field the alternator for testing, you disconnect that one small wire and put battery power to its terminal on the alternator.

In almost all cases like this, the regulator itself is the culprit. But obviously testing circuits and confirming the failure is the best idea.

 

[Dana67Dart]

Your header says 1 wire alternator.

But your post points to a standard Chrysler charging system.

Post some photos of what you have in the car now.

If you have a 69 dart the OEM charging system would be a round back (grounded field) alternator and a black box voltage regulator with one wire in the top and one wire out the bottom.

The voltage regulator provides a variable voltage to the field.

To full field you provide 12v to the field terminal on the alternator with the green field wire from the VR removed.

Now anything may have changed on 58 years like an upgraded charging system which is full fielded differently.

Note have all lights and devices accessories off before do this and don't do it for long.


There are other and better testing methods outlined in the FSM available from mymopar.com free

 

[nutz]

Yes oe one wire
So if I send 12v to the field wire it should go full voltage
Thanks

 

[Mattax]

10.4 volt at battery
10.4 at alt

They will always measure the same when everything is off.
Just like there is great water pressure thoughout the house when nothing is running.

Regardless, get the battery fully charged before testing the alternator.
A low battery will suck a ton of current trying to recharge and that current will cause damage.

reg has what i think is two wires
so queston is to full field alt do i power (12v) or ground the field wire
then the other wire on reg i would think is key on voltage

If you ground the feed to field, the fusible links inside the regulator (if its mechanical) will melt. Poof!

The circuit on a '69 should look like this.

R3 is the feed to the rotor. The second brush is grounded.

If you want to bypass the regulator, jumper from ignition to field terminal.

 

[Mattax]

Post in thread 'Identifying Chrysler Alternators (1960-1976)'

Oct 16, 2020

Grounded-brush Alternator
One brush assembly is grounded to the housing.
The other brush is insulated from ground and has a terminal.
The terminal gets connected to the output wire from the voltage regulator.

How this works.

Line voltage is a power source.
Controlled current is how much, if any, electricity is allowed to flow through the rotor.
The more frequently the electricity is allowed to flow through, the stronger the electromagnetic field is.

There is only one wire to the field because the regulator controls the current flowing...

• Mattax

if its a mechanical regulator, remove the top and you'll see if the points are sticking or either fusible link is melted.

 

[nutz]

Thanks great info
The reg looks like someone opened before
Has a couple of self tapping screws in it
Anybody make a quality reg anymore
I bought a alt from one of the guys here for when I do my swap ...are v8 and 6 the same alt

 

[Dana67Dart]

Yes oe one wire

Just for future.

The term 1 wire refered to INTERNALLY regulated Alternators. With only a power wire (some have a sense wire as well)

The OEM stock Chrysler alternators came in two verities.

1. "Grounded field" (typically round back) where one of the field terminals in the alternator is grounded inside the alternator and the other is provided a variable voltage (6 to 10 volts) to very the field current.
2. "Isolated field" (typically square back) where both field wires are isolated from ground. Battery voltage is supplied to one field terminal and the other receives a variable GROUND from the voltage regulator.

Modern rebuilds sometimes, due to lack of round back cores, use a square back isolated field alternator and internally (or externally) ground one of the field terminals making it function like a grounded field alternator. It can be deceiving because typically they clip off (but not completely) the spade part of the terminal that is grounded and since it is a square back people sometimes hook a wire to it thinking it is an isolated field alternator.

Grounded field




Isolated field

 

[nutz]

Yes I knew about the 2 wire
Thanks