Dual Field Alternator
#1429855
05/03/13 09:34 PM
05/03/13 09:34 PM
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Posts: 183 Charleston, SC
bronco9588
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How does the Chrysler Dual Field Alternator work? What causes it to "turn off"/ "turn on" and go to full load?
The story behind this is that Mancini Racing sold me a "three-wire" alternator that is not a three wire alternator. I am very displeased with them and will not be doing business with them again. I am putting in a new wiring harness and need to make sure that I wire this guy correctly. Thanks.
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Dual Field Alternator
[Re: bronco9588]
#1429856
05/03/13 09:42 PM
05/03/13 09:42 PM
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Joined: Jan 2007
Posts: 7,664 IN
ahy
master
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master
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IN
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On the alternator, have you requested exchange? I've dealt with Mancini a good bit and they handled a little "oops" promptly and correctly for me. The alternator should have a post for the charge wire and two spade terminals for the wires that energize it and control output. The link from the archives shows the layout. http://www.moparts.org/Tech/Archive/elec/21.html
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Re: Dual Field Alternator
[Re: RapidRobert]
#1429858
05/03/13 11:50 PM
05/03/13 11:50 PM
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bronco9588
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73 charger... one large and two small. Are the two smalls identical?
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Dual Field Alternator
[Re: bronco9588]
#1429862
05/04/13 09:06 AM
05/04/13 09:06 AM
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Joined: Jan 2003
Posts: 21,076 Niles , Ohio
therocks
oh wait.but hey.lets see.oh yeah.
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oh wait.but hey.lets see.oh yeah.
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The regulator turns the Alt on and off.Battery charge and temp makes the demand of how much of a charge it puts out.73 would be a dual field alt.If you told them you wanted one for a 73 thats what it would be.The fields are basically the same.Rocky
Chrysler Firepower
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Re: Dual Field Alternator
[Re: therocks]
#1429863
05/04/13 10:41 AM
05/04/13 10:41 AM
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Posts: 1,318 Ohio
jlatessa
pro stock
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pro stock
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Ohio
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On the same thread, does it really make any difference if your alternator puts out 15 volts unregulated? When I had it checked, the store said "that's too high". I thought the regulator determines the voltage going to your system. Thanks, Joe
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Re: Dual Field Alternator
[Re: John_Kunkel]
#1429865
05/04/13 04:56 PM
05/04/13 04:56 PM
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bronco9588
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So "on" would be 12volts, "off" would be nothing, and full load would be 0 volts on the sensing wire? Thanks.
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Dual Field Alternator
[Re: bronco9588]
#1429866
05/04/13 06:46 PM
05/04/13 06:46 PM
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Joined: Jan 2003
Posts: 25,878 Rio Linda, CA
John_Kunkel
Too Many Posts
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Rio Linda, CA
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There is no "on" or "off", the alternator always tries to put out more than battery voltage. The blue wire will always have battery voltage when the key is in the RUN position.
What we refer to as a 12V system is actually a 14V system (I'll probably get some disagreement here) but all of the components in a 12V system are built to handle 14V+.
The INTERNET, the MISinformation superhighway
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Re: Dual Field Alternator
[Re: John_Kunkel]
#1429867
05/04/13 07:59 PM
05/04/13 07:59 PM
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bronco9588
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So i purchased a wiring harness from rebel wiring. Anyways, the harness has a "alternator excitor" wire. I am assuming this supplies 12 volts (or 14) when the accessory bus is energied I.e. when the ignition is in run. I didn't want to damage anything as the voltage regulator would only sense 12 volts once the key is off start. It would "see" no volts until I let go of the key. Is this an issue?
'73 Charger Petty Blue, Black Vinyl, and Gill Slits
727 torque-flight
400 BB Chrysler
8 3/4 rear
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Re: Dual Field Alternator
[Re: bronco9588]
#1429870
05/05/13 05:11 PM
05/05/13 05:11 PM
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Joined: Jan 2003
Posts: 25,878 Rio Linda, CA
John_Kunkel
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The Rebel Wiring harness is pretty much the same as the factory except for ther wire colors. The "alternator exciter" wire is probably the same as the factory blue wire...it is powered only when the switch is in the RUN position; the "accessory bus" (?) plays no part in the charging system.
The INTERNET, the MISinformation superhighway
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Re: Dual Field Alternator
[Re: bronco9588]
#1429873
05/05/13 10:21 PM
05/05/13 10:21 PM
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Joined: Jun 2008
Posts: 1,822 Colorado
denfireguy
top fuel
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top fuel
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Colorado
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Quote:
Quote:
There is no "on" or "off", the alternator always tries to put out more than battery voltage. The blue wire will always have battery voltage when the key is in the RUN position.
What we refer to as a 12V system is actually a 14V system (I'll probably get some disagreement here) but all of the components in a 12V system are built to handle 14V+.
I'm pretty sure the regulator uses pulse width modulation to work... under your logic, if the alternator ever saw ground it would go to max current to try to get back to 14 volts. If it sees 14 volts it would reduce ampacity. What happens if it sees nothing... I.e. the wire is disconnected?
Mopar alternators with electronic regulators did not employ pulse width modulation. Rather, the battery voltage through the ignition switch was fed to one terminal. The other terminal is connected to the diamond shape pass transistor on the regulator. It operates in linear mode. The output to the field wire can vary from about ten volts down to .7 volts. At .7 volts, the transistor is in full conduction. The .7 of a volt is the result of the junction voltage typical of a silicon transistor and that is as close to zero as it till get and the full battery voltage less distributed wire resistive loss and junction loss will appear across the field and maximum output is achieved. Pulse width modulation works with square waves and generates massive amounts of electrical noise that would render that era's AM radios pretty unusable. I doubt Chrysler engineers even considered it. Craig
2014 Ram 1500 Laramie, 73 Cuda Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango Only previous Non-Mopar: Schwinn Tornado
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