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  #1  
Old 10-15-2005, 06:46 AM
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kreb kreb is offline
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My alternator has always had a problem charging at startup. I have to rev the motor after starting so the alternator will will go above 10volts to 13 or 14. i have been running this way for 7 years unable to solve the problem.

well recently i can not get the alternator to start working properly. The alternator did this before i replaced the original 3 or so years ago. I can tell that the headlights and gauge lights brighten when the voltmeter reads properly. so i am confident it is not a faulty reading. can the voltmeter have a problem to prevent the alternator from charging?

i have driven the car for a couple of days and the battery has not died.
i am away at school so i don't have all my tools but i got my hands on a voltmeter. i appreciate any help.

the belts look good and tight. there does not seem to be and sqealing or noises from the alternator.

benjamin
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1991 Grand Wagoneer
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'85 grill, '78 WT wheels
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Old 10-15-2005, 12:29 PM
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Spectre Spectre is offline
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Time for a new alternator. Sounds like the exciter wire was unplugged, or your alternator had been rigged to be a "one wire" setup, which can cause what you describe.
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Old 10-16-2005, 04:15 AM
Joe Guilbeau Joe Guilbeau is offline
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Quote:
Originally posted by kreb:
My alternator has always had a problem charging at startup. I have to rev the motor after starting so the alternator will will go above 10volts to 13 or 14. i have been running this way for 7 years unable to solve the problem.

well recently i can not get the alternator to start working properly. The alternator did this before i replaced the original 3 or so years ago. I can tell that the headlights and gauge lights brighten when the voltmeter reads properly. so i am confident it is not a faulty reading. can the voltmeter have a problem to prevent the alternator from charging?

i have driven the car for a couple of days and the battery has not died.
i am away at school so i don't have all my tools but i got my hands on a voltmeter. i appreciate any help.

the belts look good and tight. there does not seem to be and sqealing or noises from the alternator.

benjamin
Your alternator is designed to do just as you described. The SI-Series of Delco alternators have to be revved up about 1500 to 2000rpms in order to set up a magnetic field in order to create an induced voltage.

"....well recently i can not get the alternator to start working properly. The alternator did this before i replaced the original 3 or so years ago. ... What does this mean? I don't understand!

You go on to say that:

"...I can tell that the headlights and gauge lights brighten when the voltmeter reads properly. so i am confident it is not a faulty reading. can the voltmeter have a problem to prevent the alternator from charging?..."

Am I to assume that your Voltmeter is intermittently reading low? Perhaps you have a loose wire (check your No. 1/ No. 2 Terminals on the alterntor. If either of these wires has a problem or is not secured is a ship shape fashion then you very well might experience problems that you describe.

So, witht he voltmeter you should be reading 13.25 volts DC on a battery that is being fully charged by the alternator...this reading is when the vehicle is not running.

Start the vehicle and blip the throttle with the hood open as you are monitoring the battery voltage with the voltmeter. You should read between 13.85 and 14.85 volts DC (depending on the specific regulator inside the alternator).

Anything below or above this is an indication that you have problems with either your wiring that tells gives the alternator 12Vdc (No. 2 Terminal) and the voltage delivered to the Regulator (No. 1 Terminal) through the 15-Ohm resistor. This sets the regulator sense voltage to the appropriate level so that the regulator can properly control the alternators output.
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Joe Guilbeau<br />1983 Cherokee Laredo WT (SJ-17), 360/229/727/D44/D60 4.10 Gearing, 8-lug hubs, Edelbrock Performer w/EGR Intake, Mallory Unilite Series 47 Photo-Optic Infrared Trigger Vacuum Distributor, Mallory Surge Protector, Mallory Promaster Coil, Holley Pro-Jection TBI 502-Analog, FlowKooler High Output Water Pump, Staggered 4-Core Custom Industrial Radiator, HD Fan Clutch, Dual Electric Fans, CS130 Delco 105-Amp Alternator, Oil Bypass Mods at Rear of Block and Distributor Oiling, Superlift 4\" Suspension, Rancho RS5000\'s, Hi-Tech 31\" Re-Treads, Aero 33 Gal Tank w/Skid Plate, Custom Rear \"Longhorn\" Bumper
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  #4  
Old 10-19-2005, 08:08 AM
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kreb kreb is offline
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sorry for the late reply, i have trouble accessing the internet from school.

Joe-
Since about a year after I bought the Wag I would have to rev the throttle to start the alternator charging. About three years ago i replaced the alternator hoping that it would fix this issue, as well as a faulty regulator. I still had to rev the throttle to start charging on the new alterntor. The voltmeter would read about 13V.

A week ago i noticed the voltmeter was staying about 10V. The battery finally drained and I can not start the motor. I checked the voltage on the uncharged battery and it is at 11.9V. I did not have a chance to check it before it drained. I am going to charge the battery as soon as a can get a hold of a charger. Is there anything else i can check in the mean time while the rig is not running? If you need more info, just ask.

thanks
benjamin
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1991 Grand Wagoneer
360/ 2150
4" Rusty's lift 32x11.5 BFG KM, 1.5" block rear MSD/TFI, Pioneer sound
'85 grill, '78 WT wheels
houston, tx
hermanbloom79@yahoo.com
"if you don't have time to do it right, you don't have time to do it twice." - stolen from another board member who's name i can't recall
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  #5  
Old 10-19-2005, 08:17 AM
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Spectre Spectre is offline
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That sounds like there's a break in the exciter wire, or the wire is disconnected somewhere.
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  #6  
Old 10-19-2005, 09:36 AM
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Ted_Z Ted_Z is offline
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Quote:
Anything below or above this is an indication that you have problems with either your wiring that tells gives the alternator 12Vdc (No. 2 Terminal) and the voltage delivered to the Regulator (No. 1 Terminal) through the 15-Ohm resistor. This sets the regulator sense voltage to the appropriate level so that the regulator can properly control the alternators output.

-------------------
Joe Guilbeau
-
Joe you've got this wrong.

The sense wire goes directly to the battery side of the starter solenoid. No resistor.

The resistor wire is to limit the current to the field windings. Once the revs pick up and the alternator becomes self exciting, the current drops to zero.
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  #7  
Old 10-20-2005, 05:11 AM
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kreb kreb is offline
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I am a still a novice when it comes to the electrical system. could you explain the exciter wire ( is this one of the two connections at the alternator?) is there a fusible link connected with the alternator that could have been ruined.

benjamin
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1991 Grand Wagoneer
360/ 2150
4" Rusty's lift 32x11.5 BFG KM, 1.5" block rear MSD/TFI, Pioneer sound
'85 grill, '78 WT wheels
houston, tx
hermanbloom79@yahoo.com
"if you don't have time to do it right, you don't have time to do it twice." - stolen from another board member who's name i can't recall
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  #8  
Old 10-20-2005, 06:16 AM
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Ted_Z Ted_Z is offline
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Exciter wire is the same thing as the field wire. This goes to switched 12V. Its one of the two wires in the plastic connector

Fusable link would go to the batt (output) connection (third connector on the alternator).
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  #9  
Old 10-30-2005, 06:56 AM
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kreb kreb is offline
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i finally had a free moment between assignments. the battery and power connection to the alt have the same voltage reading(tested with the engine running.) when i blip the throttle there is no jump in voltage.

i figure now that it is definitely the alternator. the fusible links seemed fine.

to clarify i have two connections at the alternator. one red wire to a post on the alt and a plastic connected with a red and a black wire in the conncetor.

i figure that the red wire on the post provides power to the alternator. the red wire in the conncetor is the field wire, is the black wire a ground?

benjamin
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Kreboneer
1991 Grand Wagoneer
360/ 2150
4" Rusty's lift 32x11.5 BFG KM, 1.5" block rear MSD/TFI, Pioneer sound
'85 grill, '78 WT wheels
houston, tx
hermanbloom79@yahoo.com
"if you don't have time to do it right, you don't have time to do it twice." - stolen from another board member who's name i can't recall
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  #10  
Old 10-30-2005, 02:17 PM
mdill9 mdill9 is offline
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One wire is the sence wire (connected to the
battery, hot all the time) to tell the regualtor
the batt. voltage. the other wire is exciter/field
wire, switched to power though a resitor in the
engine wiring harness. Undo the plug, you should
have 0 ohns between the batt+ terminal and one wire
all the time, the other wire should be open to the + terminal, ignition off, and 50 ohms (don't
take the value to serious, I don't remeber the spec.
off the top of my head but that +/- 100%) with
ignition on.

this is the wire that should supply field current
to the alt at low RPM's and just after start,
after the alt is fired up the internal diode trio
does that job, so I agree it sounds like there
is a problem in this wire.

Mike D.
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  #11  
Old 10-30-2005, 05:13 PM
Joe Guilbeau Joe Guilbeau is offline
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Quote:
Originally posted by Ted_Z:
</font><blockquote>quote:</font><hr />Anything below or above this is an indication that you have problems with either your wiring that tells gives the alternator 12Vdc (No. 2 Terminal) and the voltage delivered to the Regulator (No. 1 Terminal) through the 15-Ohm resistor. This sets the regulator sense voltage to the appropriate level so that the regulator can properly control the alternators output.

-------------------
Joe Guilbeau
-
Joe you've got this wrong.

The sense wire goes directly to the battery side of the starter solenoid. No resistor.

The resistor wire is to limit the current to the field windings. Once the revs pick up and the alternator becomes self exciting, the current drops to zero.
</font>[/quote]Well, I could have done a better job of describing this, my explanation above is pretty poor.

Here are some additional details...

Delco SI-series internally regulated alternator have the following connections.

One large connection that is the Alternator output, known as the Bat, this connection has "Bat" cast into the housing (aftermarket housings may not incorporate these markings).

Two additional tabs (inputs to the internal regulator) are used to interface the vehicles wiring harness, these have "1" and "2" cast into the housing next to them. A two terminal Molex connector is generally used to connect the wiring harness to the regulator circuit.

Here are the details on the individual terminals:



"Bat"- this terminal is for the alternator output to the battery. On some jeeps this output goes directly to the ammeter inside the cab, and returns and has a fusible link in series somewhere along the line. Later versions used a voltmeter, and this terminal went to the solenoid and on to the Pos-Terminal of the battery.

"1"- this terminal (usually closest to the "Bat-terminal") is fed from the Ignition thru a lamp ("idiot light"), and is used to supply the magnetic field inside the alternator with the voltage needed to operate. When the engine is running, if the idiot light is on, the output voltage of the alternator is out of specification.

Some vehicles utilized a resistor wire of 15.6 Ohms in lieu of the lamp to drop the voltage at this terminal to specified levels (this may be regulator specific).

For those of you who are not happy with the Ni-Chrome wire that was part of the OEM wiring, I have a located a source for Ni-Chrome resistor wire that will satisfy your requirements should you wish to keep these original alternators intact.

You may purchase a 20-foot section of Stock Number 1027 Ni-Chrome wire at 3.75 Ohms/Foot for a mere $10 dollars at the following source.

Since you need 15 Ohms, 4-feet of this wire will work nicely, or Stock Number 1029 at 9.40 Ohms/Foot will work out nicely at a total length of about 1-Foot and 7-inches, which cleans up the engine bay nicely.

http://members.socket.net/~llile/index.htm

The lamp limits the voltage to the "Field" terminal, and this current limited voltage is what tells the regulator to start/continue/stop charging.

When the alternator begins to charge, the voltage increases at the battery.

This increase in voltage eventually reaches a point (as the alternator charges the battery) to where it is equal to the voltage divider circuit designed into the alternators regulator. Thus they equalize out and the voltage being fed to the "1"-Terminal during normal vehicle operations the lamp only lights when there is an over-voltage or under-voltage condition.

The “idiot” light is there to act as a “visual enunciators” under voltage and over voltage conditions at the battery. Either of these conditions will energize the "idiot" light.

"2"- this terminal can be fed from the positive battery post or the starter solenoid where the positive battery post connects to the solenoid switch.

This is an input to the alternator that is used to sense the battery voltage; some applications use a modified regulator circuit and may only use one or even perhaps neither of these two regulator terminals. One-wire alternators come to mind here.

Not to put too fine a point on it...

The Number-2 terminal above is connected to (most likely) the solenoid terminal hooked to the positive post of the battery, or is set up a for remote sense (the preferred voltage monitoring location), and connects to the braised or soldered fan-out connection, and senses the charge condition of the battery, and routes this voltage to a voltage divider network (R2/R3) with a capacitor (C1) to filter it inside the regulator circuit.

This voltage divider network limits the current discharge to negligible amounts.

In the charging mode the circuit operates in the following manne...

The voltage divider (R2/R3) supplies a reference voltage to Zener diode (D2), which is now “Off”, and thus blocks any voltage so that there is no forward bias on the base to emitter junction of the NPN Transistor TR2, therefore it cannot conduct. This results in the emitter of TR2 being pulled “High”. So now base drive can be applied to TR1.

The regulator circuit is now being fed from Terminal 1, which provides base drive to TR1, thru R1 and D1.

D3 is reversed biased and is blocking current flow. With base drive, TR1 is forward biased, and it acts like an “On/Off” switch. When it is on, it provides a path for current to flow from the rotor’s field windings (supplied by Terminal 1) to ground thru its emitter/collector junction.

Therefore the alternator is charging at this point, because current is flowing from the ignition switch thru the No. 1 Terminal on the alternator, thru the field windings coil and continues on thru the emitter/collector junction of TR1, and to ground.

The lamp circuit cannot supply enough current to the field windings to sustain or generate the magnetic field in order to induce a voltage output on the Stator windings.

So, in many applications the vehicles engine must be revved to a higher RPM in order to generate enough initial field strength so that the induced EMF is sufficient to self maintain it.

The battery is now being charged by the alternator, and therefore its voltage begins to rise.

The voltage divider network (R2/R3 which is factory adjusted) begins to see the voltage across R3 rising, in time the alternator charges the battery sufficiently so that the voltage rise across R3 reaches a threshold. This threshold voltage forces Zener diode (D2) to be biased into conduction, which in turn provides TR2 transistor with base drive.

TR2 transistor’s base to emitter is now forward biased and therefore its collector voltage is essentially “switched” to a diode drop potential above ground. This turns off base drive to TR1, which “switches off” and no longer provides a path for the rotor field current circuit, and the rotor field collapses, because there is no longer any current flowing thru its coil.

Bringing the junction of R1 and the Cathode of D1 to ground potential results in reverse biasing the cathode/anode junction and therefore the Base to Emitter junction of TR1 is now reversed biased and it no longer conducts and switches off.

The following diagram illustrates the point, as the base drive controls the “On/Off switching” of TR1… when the switch is on, the rotor coil current flows, when the switch if off, no current flows in the rotor and the field collapses.




Thus the alternator generates Alternating voltage and current. A diode trio rectifies the current that flows through a transistor, which feeds the field windings of the stator, self excitation if you will…don’t even go there, I’ve heard it all before.

This happens over and over...energizing and collapsing the magnetic field thereby controlling the alternator output, it is a wonder that these alternators last as long as they do.

[ October 30, 2005, 11:25 PM: Message edited by: Joe Guilbeau ]
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  #12  
Old 11-03-2005, 07:33 AM
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kreb kreb is offline
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Joe-
The battery wire and no. 2 wire both read the same battery voltage. but the resistance wire, no.1, reads .02V. i am guessing this is my problem.

I saw that you listed a source to purchase replacement resistor wire. When i click on the link i am taken to a registration sight. Is this correct?

From the altenator where does the no.1 wire go to? it looks like it goes behind the motor to somewhere.

Everyone's responses have been very helpful. thank you

benjamin
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1991 Grand Wagoneer
360/ 2150
4" Rusty's lift 32x11.5 BFG KM, 1.5" block rear MSD/TFI, Pioneer sound
'85 grill, '78 WT wheels
houston, tx
hermanbloom79@yahoo.com
"if you don't have time to do it right, you don't have time to do it twice." - stolen from another board member who's name i can't recall
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  #13  
Old 11-04-2005, 01:11 PM
Joe Guilbeau Joe Guilbeau is offline
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That site sould be for the NI-Chrome wire source...I will look at my alternator page to see if I screwed up the link in cutting and pasting....hang on....Yep the site is gone.

http://oljeep.com/gw/alt/edge_Alternator_Theory.html

The above is my alternator theory page and that Ni-Chrome Wire link is gone.

Just go out and get a 1/2 Watt 15-Ohm resistor from Radio Shack (...You got answers?...We got questions...?)
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Joe Guilbeau<br />1983 Cherokee Laredo WT (SJ-17), 360/229/727/D44/D60 4.10 Gearing, 8-lug hubs, Edelbrock Performer w/EGR Intake, Mallory Unilite Series 47 Photo-Optic Infrared Trigger Vacuum Distributor, Mallory Surge Protector, Mallory Promaster Coil, Holley Pro-Jection TBI 502-Analog, FlowKooler High Output Water Pump, Staggered 4-Core Custom Industrial Radiator, HD Fan Clutch, Dual Electric Fans, CS130 Delco 105-Amp Alternator, Oil Bypass Mods at Rear of Block and Distributor Oiling, Superlift 4\" Suspension, Rancho RS5000\'s, Hi-Tech 31\" Re-Treads, Aero 33 Gal Tank w/Skid Plate, Custom Rear \"Longhorn\" Bumper
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Old 11-04-2005, 01:17 PM
Joe Guilbeau Joe Guilbeau is offline
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This place is "Down Under"

http://www1.jaycar.com.au/productView.asp?ID=WW4040
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Joe Guilbeau<br />1983 Cherokee Laredo WT (SJ-17), 360/229/727/D44/D60 4.10 Gearing, 8-lug hubs, Edelbrock Performer w/EGR Intake, Mallory Unilite Series 47 Photo-Optic Infrared Trigger Vacuum Distributor, Mallory Surge Protector, Mallory Promaster Coil, Holley Pro-Jection TBI 502-Analog, FlowKooler High Output Water Pump, Staggered 4-Core Custom Industrial Radiator, HD Fan Clutch, Dual Electric Fans, CS130 Delco 105-Amp Alternator, Oil Bypass Mods at Rear of Block and Distributor Oiling, Superlift 4\" Suspension, Rancho RS5000\'s, Hi-Tech 31\" Re-Treads, Aero 33 Gal Tank w/Skid Plate, Custom Rear \"Longhorn\" Bumper
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