alt, single field to double field?

-
barbee6043

barbee6043

barbee 6043
FABO Gold Member
Joined
Jul 20, 2008
Messages
20,524
Reaction score
10,117
Location
Shepherd, Texas ( SE Tx)
65 dart slant,..... I just got new 60 amp alternator ,it is square back, it has the 2 field wires, have correct style vr for this car (points still),.....
I know I've read on here somewhere about maybe grounding one of the field wires OR what else?????? thanks for the answer!!
 
That is correct. You can use the "dual field" alternator on a "single field" car by simply grounding one of the field plugs. Personally, I would add a grounding wire and plug to 'plug in' the ground connection (if I was doing it for someone else), but you can remove the plastic spacers from one of the field plugs (on the alternator) to ground the field with the mounting screw of the field plug.
 
Badvert65 said:
That is correct. You can use the "dual field" alternator on a "single field" car by simply grounding one of the field plugs. Personally, I would add a grounding wire and plug to 'plug in' the ground connection (if I was doing it for someone else), but you can remove the plastic spacers from one of the field plugs (on the alternator) to ground the field with the mounting screw of the field plug.
Click to expand...

let me back up a little. I had ordered a single field alternator. they did send a square back. I just went to pout it and I see the second field terminal has no placed to slide the wire connection to.
I've heard guys on here getting the later square back that CAME setup to use 1 field wire????
if the rebuilder sets it up to use with a single field, THEN wouldn't that connection NOT have that plastic spacer insulator under that connection!?????? thanks
 
Or get a wiring diagram for both the single field and double field systems. The double field also upgraded the voltage regulator. I think that you may just be able to run the "other" alternator field wire to the extra terminal on the new style voltage regulator (to me the late 60's style is my baseline).


So look at the service manual diagrams for the proper applications and compare what they added in the wiring for the extra field wire for the alternator and add it to your car.


Here's a link for some free service manual downloads:

http://www.mymopar.com/index.php?pid=109
 
barbee6043 said:
let me back up a little. I had ordered a single field alternator. they did send a square back. I just went to pout it and I see the second field terminal has no placed to slide the wire connection to.
I've heard guys on here getting the later square back that CAME setup to use 1 field wire????
if the rebuilder sets it up to use with a single field, THEN wouldn't that connection NOT have that plastic spacer insulator under that connection!?????? thanks
Click to expand...


You have to be careful. Sometimes the square back will interfere with the brackets/ fuel pump, head and you can't get it to fit when swapping it in for the older applications (pre square back).



In the late 60's they used the "regular" housing and a single field wire.

In 70 they added the 2nd field wire to the similar housing.

Sometime later in the 70's (I think between 73 and 76) they changed to the square back.


You could ground the 2nd field terminal on the square back if it will fit.

Or upgrade your voltage regulator to the post 70 style and add the extra wire for the 2nd field terminal coming off the alternator. I don't think it will be that hard.
 
that's what i'm saying, the second terminal will NOT take the usual connection like the single field (green) wire would. Its looks like the "normal" connection EXCEPT it has no place to slide on the wire. just an oblong brass connection on top of that plastic insulator. SINCE I asked for a single field alternation, did the builder make it a single wire alt ( although the square back design)?????????????
 
barbee6043 said:
that's what i'm saying, the second terminal will NOT take the usual connection like the single field (green) wire would. Its looks like the "normal" connection EXCEPT it has no place to slide on the wire. just an oblong brass connection on top of that plastic insulator. SINCE I asked for a single field alternation, did the builder make it a single wire alt ( although the square back design)?????????????
Click to expand...



Do you have a picture that you can post? I can't picture what you're sayin' here.
 
he's saying there's no 2nd field terminal on the back of the alternator even though there is a place for it. if there is no terminal for a 2nd field, then you have a single field alternator. No?
 
A multimeter would quickly tell you if the 2nd terminal is grounded to the case, as needed with your "1 field wire" alternator.

The whole reason Chrysler changed to the 2-field wire setup was because transistors then could only switch the low-side, which required +12 V on the other terminal. The earlier mechanical Vreg switches the high side. Today, that can be easily done with transistors, which is why there are "1 field wire" electronic Vreg's available.
 
In some of the old applications, the square back alternators will not directly bolt in place of the older style alternators. The back interferes with the head or brackets or fuel pump (I can't remember which one). I would test fit the alternator to see if it will fit before going further. If it doesn't fit, then you need the older style housing before square back.
 
O K! I did get the square back in, no problem except it hit the head/ valve cover which I barely got the fan belt on, but did. seems was set up for the single field wire. ordering the earlier style alternation doesn't necessarily work, as they will sometimes send the square back one anyway.
I stated a thread last week on "start issue". it all started when I switched out my 65 dart battery to start the tractor, returned it back to dart, went brain dead, and for a split second put battery wires on *** backwards, for a split second. I go to start the dart, it would start but only keep running if I help the key over to the start pos. (ign?).
I then switched to a NEW ballast and it would start/run normal/ I see some smoke coming off the NEW ballast, maybe just normal from being brand new!???? the VR I had on there was a new one I had put on there while back. I have only yard drove this car, needs exh, no reverse, etc!
so then I bigin tp esearch all the electrical problems/fixes on here. get out my dandy " free" HF meter, which I hardly know squat about and try getting V reading here and there!!!!!
SOoooooo....... one question: I can put the meter (set at where it says 10A) on the battery, ( no cables hooked to it), it will read like 13.5 and steadily keep going down in numbers, quickly....... does same thing when car is running, will say like 13.5,split second late 13, then like 12.7 etc......
I the coil + was reading like 3.8, which I understand is low. the fished it out, was new, and put another new one on there I had, same reading
when running the amp gauge reads very slightly to the discharge side of center.
do I have the meter se right. ??? can't find instructions! LOL
or as I have studied on here, a fall in current somewhere?????
 
WOW!!!! I found my H F multi meter INSTRUCTIONS! I had it set wrong, new readings, the battery ( not running, nothing hooked to it), 12.5
running bout the same maybe 12.4, reads constant numbers. the coil + reads like 7.5 and ballast reads like 11 and 4.
I will put trickle charge on battery tonight. see if I can get it back up to full and read it. its a big group 27 2-3 years old. I have a new group 24 interest battery I can try to but was afraid if there was short somewhere I could hurt it. ( can afford that!)...
I will glue the multi meter instructions to me chest so I can find them again!????
 
What is the output voltage AT THE ALTERNATOR? Should be 13.5V at 1500 RPM or so. If you have less then that you probably replaced the alternator because the voltage regulator was getting flaky (as the mechanical type are prone to do). If you have a steady 13.5V at the alternator and less at the battery, you have a dirty connection somewhere, supply or ground.

Rebuilding a Mopar alternator is simple and cheap, why hassle with the parts store "reman" units?
 
C130 Chief said:
What is the output voltage AT THE ALTERNATOR? Should be 13.5V at 1500 RPM or so. If you have less then that you probably replaced the alternator because the voltage regulator was getting flaky (as the mechanical type are prone to do). If you have a steady 13.5V at the alternator and less at the battery, you have a dirty connection somewhere, supply or ground.

Rebuilding a Mopar alternator is simple and cheap, why hassle with the parts store "reman" units?
Click to expand...

I got out there and checked with my handy dandy free H F meter! I left trickle charge on battery overnight. it read 13.05 before doing anything, got it started and warmed up till it would idle good. the battery is reading 13. 3 runnin at 1500 rpm or liitle more. the alt shows like 13.4-.5/ the coil + is like 8- 8.5, the coil neg is bouncing around 4. or so.
if I remebe r right the high side of ballast was like 11 something and the low side was probably 4 something, I forgot to write that down.
last fall when I forst got the transplanted slant in and running, I did clean the terminals at the bulkhead and put some dielecric grease there, but was all the did to wiring. I assume i'm losing 2/10 volts in the wiring system??
back years when I would actually restore a mopar, first thing I did was buy a new repop eng wiring harness. now days, my list of parts I need exceed my disposable income......LOL
could you tell me what the alt field wire does??? I can see its insulation is cracked in my places. is that a likely wire to repace or which ones under the hood???? thanks for all the input.
 
You should be ok if you are putting out between 13.3 - 15 volts when running.
 
krazykuda said:
You should be ok if you are putting out between 13.3 - 15 volts when running.
Click to expand...

yes, I meant to say,,, alt was putting out like 13.5 at 1500 rpm, and i read at same time 13.2 at battery, so I guess by info here I lose 3/10 v somewhere in wiring, wondering if any likely wire to look at under hood?
an what does the al t field wire do exactly???? thanks
 
0.3V loss isn't too awful, clean the usual places: bulkhead, ammeter, battery cables, starter relay. 65 bulkhead should have screw lug terminals for primary charge wire connections.

You should be seeing full system voltage on the high side of the resistor, and about 9.5V on the low side (coil +).
 
Sorry but no; 13.5v out of the alternator is not working right. Residual magnetism in the field core can cause the alternator put out a low but inadequate voltage with VR not working or not connected.

DO us all a favor.... seriously:
GO to the store and buy and Brand new 9v transistor battery and measure the voltage out of that with your HF meter. It shoudl read 9.6 or 9.7 v. We *and you need to know if your meter is reading right since the voltages you are getting are in an indeterminate range. Another problem with the reported data is that the 13v out of the battery after a charge is too high IF you removed the charger and let it 'rest' for an hour or two before measuring; the 'surface charge' created in the battery in the charging process has to dissapate before a valid voltage measurement can be made. So, either you procedure is not right or the meter is inaccurate. We need to know which. Honestly, doing anything else is wasting your time and ours; these tests have to be done right to get useful results 'specially when help is over the internet.
 
nm9stheham said:
Sorry but no; 13.5v out of the alternator is not working right. Residual magnetism in the field core can cause the alternator put out a low but inadequate voltage with VR not working or not connected.

DO us all a favor.... seriously:
GO to the store and buy and Brand new 9v transistor battery and measure the voltage out of that with your HF meter. It shoudl read 9.6 or 9.7 v. We *and you need to know if your meter is reading right since the voltages you are getting are in an indeterminate range. Another problem with the reported data is that the 13v out of the battery after a charge is too high IF you removed the charger and let it 'rest' for an hour or two before measuring; the 'surface charge' created in the battery in the charging process has to dissapate before a valid voltage measurement can be made. So, either you procedure is not right or the meter is inaccurate. We need to know which. Honestly, doing anything else is wasting your time and ours; these tests have to be done right to get useful results 'specially when help is over the internet.
Click to expand...

i'll pick up a new 9 v battery in a m. like I said, I put the little charger on that battery and it ran all night. truth is, I really don't remember how long it sat after I cut off charger. I thing couple of hours, but I really had about 10 things all going on this morning.
don't want to waste anyone's time.
 
Awesome, thanks for doing that. We can trust you meter to be accurate! The 13v at the battery after charging probably means it did not rest long enough to get a proper reading.

The spec for a properly operating older 35A alternator is 13.7 to 14.3 v charging voltage to the battery with the temp at 75F measured just above the VR. If it was really hot in the engine compartment, then it could be down as low as 13.4v; the regulator will get effected by temperature as well as the windings and diodes in the alternator. But I suspect that your temps are on the cool side now and the voltages will tend to be towards the high end for everything working well. So that is the reason to say that 13.3v at the battery is not good.

BTW, to answer your question about the field wire....well, the literal answer is to carry the field current from the VR to the field. The field is acually a copper wire winding on the rotor (the rotating part connected to the pulley) of the alternator. The current in the field winding sets up a magnetic field around the rotor that spins around with the rotor as it is turned by the engine. This spinning magnetic field creates 3 outputs of alternating current from the stator winding (the fixed, outer part of the alternator) that are then rectified by the alternator's diodes into the DC (direct current) that the car's system uses.

The amount of the field current is what the VR actually controls; if the VR increases the field current, then the rotating magnetic field gets stronger and the total voltage out of the alternator increases. As you load the system, like with turning on lights and fan blower, etc., the voltage would decrease naturally due to the increased load current. But, the VR senses this voltage decrease (through the blue IGN1 circuit that goes to the VR as well as the ballast) and reacts by increasing the field current which rasies the system voltage back up to where it should be. It does the opposite as the system load decreases.

So the question now is why the charging voltage is low. Going back to your post 3..... so the 2nd field connection is to a plastic insulator? And you have the type of VR that is original to the car that is for a single field terminal type of alternator, correct? Per post 10, then next step is to see if the 2nd end of the field is indeed internally grounded or not.

Read your meter instructions and learn how to measure resistance (ohms). Set up the meter for that and select the lowest ohm's setting.
1. As a check, put the 2 leads of the mter together and verify that you read near to 0 ohms. Then separate the 2 leads and see what the meter reads; it should blank out or read some non-numerical info; this indicates that there is very high resistance (an 'open circuit' or 'no connection').
2. Remove the green field wire from the field terminal with the connection. Then connect one lead of the meter (while in resistance mode) to the alternator case and the other lead to the 2nd field terminal. If this terminal is grounded internally, then you should see the 0 ohms reading or very close that you got when you shorted the meter leads directly. If you measure the 'open circuit' reading, then the 2nd field terminal is not internally grounded.
3. If not internally grounded, then you can start the car, set at fast idle, and while monitoring the battery voltage and the field wire connected to the 1st field terminal, then ground the 2nd field terminal for a moment and see if the battery voltage charging jumps to a more nomral range. If it does this, then you know the alternator and single field VR are working and you can figure out how to ground the 2nd terminal permanently.

Edit to add: And make sure the supposed 2nd terminal is actually a field connection.... probably is (Maybe it is marked with 'FLD'?) but you don't want to ground it otherwise. One way to check is to set your meter the lowest ohms scale and measure from one filed terminal to the other; the resistance will be very low and you will measure a couple of ohms.
 
thanks for taking the time to type all that info.
I originally had a pretty new old style round back alt. with initial testing. like I said, I had the meter set wrong first times.
yesterday, I did get a new square back alt, set from co with a single field, ( the other location for the second wire , has just a square brass deal sitting on a plastic insulator. I figure they s et it up at co to work off the single field wire.
drizzly nasty weather today. hopefully tomorrow I will have time to "start over" LOL!
so what I have here is a 2 year old big group 27 battery, fully charged, new alt( square back s etup for single field wire),,, and new vr, new ballast.
thanks for the help..
 
And the new VR is the one for a single field alternator, right? If so, it would be a rectangular shaped one with a screw terminal on one side and a stab-on connection on the other. (And perhaps a ground terminal too.) PN may be something like VR101.
 
You must log in or register to reply here.
-

Back
Top